tag:theconversation.com,2011:/africa/topics/parasites-1140/articlesParasites – The Conversation2024-03-15T17:15:03Ztag:theconversation.com,2011:article/2256032024-03-15T17:15:03Z2024-03-15T17:15:03ZTapeworm larvae found in man’s brain – how did they get there?<figure><img src="https://images.theconversation.com/files/582158/original/file-20240315-24-ctqzsd.jpg?ixlib=rb-1.1.0&rect=40%2C0%2C6669%2C4476&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/study-tapeworm-infection-caused-by-ingesting-1273229722">Rattiya Thongdumhyu/Shutterstock</a></span></figcaption></figure><p>We have all found ourselves in a place we would rather not be, a school reunion, the never-ending work meeting or a distant relative’s wedding reception. In such situations, it is often a good option to make the best of it. Well, this isn’t just the case for people, it is also an occurrence in the world of parasites – those lifeforms that live in and on us. This was the case for <em>Taenia solium</em>, or pig tapeworm which <a href="https://amjcaserep.com/abstract/index/idArt/943133">found itself</a> in an unlikely place. </p>
<p>A middle-aged man from Florida with a history of migraines went to the doctor as his headaches were becoming worse and weren’t responding to his usual drugs. The 52-year-old was sent for a CT scan, which revealed something alarming: his brain was infested with tapeworm cysts.</p>
<p>The most common route of infection is eating undercooked infected pork that contains tapeworm cysts, known as cysticercus. </p>
<p>When the parasite senses the digestive juices of your small intestine, it then knows it is time to use its curled hooks and four suckers and attach to your gut. Once here, the tapeworm is living its best life; growing to around two metres long and potentially making a home in you for up to five years. </p>
<p>During this time, the parasite will release thousands of eggs, either individually or via releasing segments of its body packed full of eggs, which all pass out in your faeces. This form of infection is largely symptomless and easily treated with antihelminthics (anti-parasite drugs) with minimal complications. </p>
<p>Although the reported patient acknowledged a habit of eating undercooked bacon, this would not explain the parasite being found in his brain, as consuming cysticercus in undercooked pork would only result in an intestinal infection. </p>
<h2>Poor hygiene is the likely cause</h2>
<p>The authors of this new study therefore hypothesised that the patient may have been infected with the intestinal form of the parasite and re-infected himself with eggs passed in his faeces through poor hygiene. </p>
<p>In countries with limited sanitation and where faeces can be used as fertiliser, the eggs people pass are usually eaten by pigs. Once in the pig, they hatch and make their way to the pig’s muscle to form cysticercus, waiting to be consumed again by humans. </p>
<p>In this case, the parasite has reverted to the cysticercus form and while seeking out muscle has accidentally made its way into the brain via the blood stream resulting in a condition called <a href="https://www.cdc.gov/parasites/resources/pdf/npis_in_us_neurocysticercosis.pdf">neurocysticercosis</a>. The parasite has still made the best of the situation, as it could carry on its lifecycle if scavenged following the death of the host.</p>
<p>Neurocysticercosis is also treated with antihelminthics, but the resulting immune response in the brain can cause more harm than good and needs to be turned down with anti-inflammatory drugs. </p>
<p>The reported patient opted for this dual treatment and is recovering with reduced brain lesions and headaches. </p>
<p>If untreated, neurocysticercosis can lead to seizures and is a <a href="https://onlinelibrary.wiley.com/doi/10.1111/epi.14068">leading cause</a> of epilepsy in developing nations with poor sanitation where cases are prevalent. With increased immigration from countries where the tapeworm is endemic, there is also an increase in cases even in countries where reports in livestock are rare.</p>
<p>The best way to avoid this unwanted guest in your intestine, or brain where neither host nor parasite are happy, is good personal hygiene. </p>
<p>Pigs are traditionally a host for many parasites – after all, there is a reason pork was forbidden in many cultures, and I personally avoid the <a href="https://www.theguardian.com/lifeandstyle/2013/sep/21/chefs-pork-pink">current fashion</a> for “rare” pork, even in the fanciest restaurants. Take a cue from the parasite: make the best of the situation and opt for fully cooked pork and you will be fine.</p><img src="https://counter.theconversation.com/content/225603/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>John Worthington works for Lancaster University. He receives funding from DSTL, the Wellcome Trust and the Royal Society. </span></em></p>A man from Florida was found to have tapeworm cysts in his brain.John Worthington, Senior Lecturer in Infection Biology, Lancaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2241652024-03-05T13:13:59Z2024-03-05T13:13:59ZThese tiny worm-like creatures in the soil can destroy pests but they can also kill crops - an expert’s guide to nematodes<figure><img src="https://images.theconversation.com/files/578226/original/file-20240227-16-a0262c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">PeopleImages/Getty Images</span></span></figcaption></figure><p>Whether you’re a gardener growing food for your household, a small scale farmer or a commercial producer, soil matters. You cannot really tell the difference between healthy and unhealthy soil just by looking at it. But there are organisms in the soil – creatures you can’t see with your naked eye – which scientists use to measure soil health. </p>
<p><a href="https://www.britannica.com/animal/nematode">Nematodes</a> are among the creatures that scientists look for. These multicellular, <a href="https://theconversation.com/all-you-need-to-know-about-the-space-travelling-nematode-a-worm-like-no-other-47949">wormlike animals</a> differ from most other organisms in the soil, such as bacteria and fungi, which are single celled. Nematodes are equipped with a digestive system. They’re also transparent, making it easy for scientists to examine their feeding habits.</p>
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Read more:
<a href="https://theconversation.com/all-you-need-to-know-about-the-space-travelling-nematode-a-worm-like-no-other-47949">All you need to know about the space travelling nematode: a worm like no other</a>
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<p>I study nematodes to use as biological control agents and also represent Stellenbosch University, South Africa, in the <a href="https://nemedussa.ugent.be">NEMEDUSSA project</a>. This is a consortium of 16 research and educational institutes across Africa and Europe who work on and study nematodes. We want to increase awareness, research and teaching about nematodes, especially in agricultural disciplines.</p>
<p>We also believe it’s important for everyone, especially those working in the <a href="https://extension.umn.edu/soybean-pest-management/soybean-cyst-nematode-management-guide">agricultural sector</a>, and even just casual food gardeners, to know about nematodes. If you grow tomatoes in your garden, for instance, <a href="https://doi.org/10.1155/2021/8820211">root-knot nematodes</a> can cause total crop failure.</p>
<p>Four main types of nematodes occur in soil. Each group has expert scientists studying their behaviour and how they can be managed in agricultural practice to minimise the amount of damage they cause. </p>
<h2>Free-living nematodes</h2>
<p>Free-living nematodes are non-parasites. They tend to feed on almost anything in the soil, including fungi, bacteria and other nematodes. In fact, without these free-living nematodes, soil is regarded as <a href="https://doi.org/10.1016/j.apsoil.2018.08.008">biologically dead</a> and unhealthy for plant growth. </p>
<h2>Plant-parasitic nematodes</h2>
<p>The unchecked build-up of plant-parasitic nematodes in unbalanced soil is every farmer’s nightmare. Such nematodes feed through a needle-like stylet, which they use as a syringe for obtaining food from the roots of plants. They have adapted their lifestyle from feeding on the outside of the root to inside it, where they are protected against the harsh soil environment.</p>
<p>Plant-parasitic nematodes can never be fully controlled. However, researchers have developed ways to keep them from multiplying to damaging levels. These techniques include planting crops that are resistant to specific nematodes or rotating with crops that the nematodes do not like.</p>
<h2>Entomopathogenic nematodes</h2>
<p>Entomopathogenic nematodes as biological control agents are <a href="https://www.researchgate.net/profile/Antoinette-Malan">my special interest</a>. They are plant allies. They feed on pest insects such as larvae and pupae that are in contact with the soil, rather than on plants. Researchers recommend that every farmer or food gardener should have entomopathogenic nematodes present in their soil because they help to keep insect numbers low. Yes, you can buy them: they’re <a href="https://www.e-nema.de/en/about-us/">available commercially</a>, including from <a href="https://biobee.co.za/solutions/biosf/">some South African companies</a>.</p>
<h2>Slug-parasitic nematodes</h2>
<p>Many slug species are in close contact with soil, so certain nematodes have adapted their feeding habits over millions of years to feed on slugs, as well as <a href="https://link.springer.com/chapter/10.1007/978-3-319-44210-5_23">some snails</a>.</p>
<p>Researchers realised that the slug nematode could be used as a biological control agent. Biocontrol involves using living organisms like pathogens or insects to control pests, rather than using more environmentally damaging chemical products. A commercial product, available under the trade name <a href="https://www.youtube.com/watch?v=JopdT8cmrh0">Nemaslug</a>®, was created in 1994 which harnessed the slug nematodes’ feeding habits for biocontrol. But it’s only available in Europe: research is ongoing to identify whether the nematode species used in the commercial product is found in South Africa and whether it’s non-toxic to local endangered molluscs.</p>
<h2>Monitor soil health</h2>
<p>My advice to gardeners and farmers, even those working at a small scale, is to regularly send soil samples for laboratory testing. This will allow you to find out what sorts of nematodes are living among your tomato plants – the “good guys” who take care of pests, or the plant parasites. There are a number of private companies (<a href="https://www.nemlab.co.za">Nemlab</a> is one example) in South Africa to do these sorts of analyses and offer advice based on the results.</p><img src="https://counter.theconversation.com/content/224165/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Antoinette Paula Malan receives funding from NEMEDUSA, Erasmus+ NEMEDUSSA project, Capacity Building in Higher Education (CBHE): Nematology Education in Sub-Sahara Africa (NEMEDUSSA). The project is funded by the European Union.</span></em></p>Four types of nematodes occur in soil.Antoinette Paula Malan, Researcher in Nematology, Parasitology, Systematics, Stellenbosch UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2235412024-02-15T03:31:18Z2024-02-15T03:31:18ZHow worried should I be about cryptosporidiosis? Am I safe at the pool?<figure><img src="https://images.theconversation.com/files/575532/original/file-20240214-30-7bq8q2.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C998%2C559&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/bright-aqua-blue-swimming-pool-students-2124280826">LBeddoe/Shutterstock</a></span></figcaption></figure><p>You might have heard of something called “<a href="https://www.abc.net.au/news/2024-02-13/nsw-health-alert-cryptosporidiosis-cases/103460468">cryptosporidiosis</a>” recently, closely followed by warnings to stay away from your local swimming pool if you’ve had diarrhoea.</p>
<p>More than 700 cases of this gastrointestinal disease were reported <a href="https://www.health.qld.gov.au/newsroom/doh-media-releases/rapid-increase-in-cryptosporidiosis-cases-hits-queensland">in Queensland</a> in January, which is <a href="https://www.theguardian.com/australia-news/2024/feb/13/avoid-swimming-pools-if-youre-part-of-australias-surge-in-diarrhoea-cases-say-authorities">13 times more</a> than in January last year. Just under 500 cases have been recorded in <a href="https://www.health.nsw.gov.au/news/Pages/20240213_00.aspx">New South Wales</a> this year to-date, while <a href="https://www.health.vic.gov.au/health-advisories/increase-in-cryptosporidiosis-cases-across-victoria">other states</a> have similarly reported an increase in the number of cryptosporidiosis infections in recent months.</p>
<p>Cryptosporidiosis has been listed as a <a href="https://pubmed.ncbi.nlm.nih.gov/12725505/">national notifiable disease</a> in Australia since 2001.
But what exactly is it, and should we be worried?</p>
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<a href="https://theconversation.com/what-lies-beneath-the-bugs-lurking-in-your-swimming-pool-51028">What lies beneath: the bugs lurking in your swimming pool</a>
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<h2>What causes cryptosporidiosis, and who is affected?</h2>
<p>Cryptosporidiosis is the disease caused by the parasite <em>Cryptosporidium</em>, of which there are two types that can make us sick. <em>Cryptosporidum hominis</em> only affects humans and is the major cause of <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9133686/">recent outbreaks in Australia</a>, while <em>Cryptosporidium parvum</em> can also affect animals. </p>
<p>The infection is spread by spores called oocysts in the stools of humans and animals. When ingested, these oocysts migrate and mature in the small bowel. They damage the small bowel lining and <a href="https://www.cdc.gov/parasites/crypto/general-info.html">can lead to diarrhoea</a>, nausea, vomiting, fever and abdominal discomfort. </p>
<p>Most people develop symptoms anywhere from <a href="https://www.health.vic.gov.au/health-advisories/increase-in-cryptosporidiosis-cases-across-victoria">one to 12 days</a> after becoming infected. Usually these symptoms resolve within two weeks, but the illness may last longer and can be severe in those with a weakened immune system. </p>
<p>Children and the elderly tend to be the most commonly affected. Cryptosporidiosis is more prevalent in young children, particularly those <a href="https://www.thelancet.com/journals/langlo/article/PIIS2214-109X(18)30283-3/fulltext">under five</a>, but the disease can affect people of any age. </p>
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<img alt="A 'pool closed' sign in front of a swimming pool." src="https://images.theconversation.com/files/575739/original/file-20240214-18-g0i5b2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/575739/original/file-20240214-18-g0i5b2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/575739/original/file-20240214-18-g0i5b2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/575739/original/file-20240214-18-g0i5b2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/575739/original/file-20240214-18-g0i5b2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/575739/original/file-20240214-18-g0i5b2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/575739/original/file-20240214-18-g0i5b2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">A number of public pools have been closed lately due to cryptosporidiosis outbreaks.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/bright-white-sign-local-outdoor-pool-2124260702">LBeddoe/Shutterstock</a></span>
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<h2>So how do we catch it?</h2>
<p>Most major outbreaks of cryptosporidiosis have been due to people drinking contaminated water. The largest recorded outbreak occurred in <a href="https://pubmed.ncbi.nlm.nih.gov/7818640/">Milwaukee in 1993</a> where 403,000 people were believed to have been infected. </p>
<p><em>Cryptosporidium</em> oocysts are very small in size and in Milwaukee they passed through the filtration system of one of the water treatment plants undetected, infecting the city’s water supply. As few as <a href="https://www.sciencedirect.com/science/article/pii/S1286457902016301#BIB26">ten oocysts</a> can cause infection, making it possible for contaminated drinking water to affect a very large number of people.</p>
<p>Four days after infection a person with cryptosporidiosis can shed <a href="https://www.safewater.org/fact-sheets-1/2017/1/23/detailed-cryptosporidium">up to ten billion oocysts</a> into their stool a day, with the shedding persisting for about two weeks. This is why one infected person in a swimming pool can infect the entire pool in a single visit. </p>
<p><em>Cryptosporidium</em> oocysts excreted in the faeces of infected humans and animals can also reach <a href="https://www.safewater.org/fact-sheets-1/2017/1/23/detailed-cryptosporidium">natural bodies of water</a> such as beaches, rivers and lakes directly through sewer pipes or indirectly such as in manure transported with surface runoff after heavy rain. </p>
<p><a href="https://www.sciencedirect.com/science/article/pii/S0043135418308728">One study</a> which modelled <em>Cryptosporidium</em> concentrations in rivers around the world estimated there are anywhere from 100 to one million oocysts in a litre of river water.</p>
<p>In <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9133686/">Australia</a>, cryptosporidiosis outbreaks tend to occur during the late spring and early summer periods when there’s an increase in recreational water activities such as swimming in natural water holes, water catchments and public pools. We don’t know exactly why cases have seen such a surge this summer compared to other years, but we know <em>Cryptosporidium</em> is very infectious. </p>
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Read more:
<a href="https://theconversation.com/explainer-what-is-gastroenteritis-and-why-cant-i-get-rid-of-it-34351">Explainer: what is gastroenteritis and why can't I get rid of it?</a>
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<p>Oocysts have been found in foods such as <a href="https://www.sciencedirect.com/science/article/pii/S0362028X22052693">fresh vegetables</a> and <a href="https://pubmed.ncbi.nlm.nih.gov/10958471/">seafood</a> but these are not common sources of infection in Australia. </p>
<h2>What about chlorine?</h2>
<p>Contrary to popular belief, chlorine doesn’t kill off all infectious microbes in a swimming pool. <em>Cryptosporidium</em> <a href="https://www.sciencedirect.com/science/article/pii/S1286457902016301#BIB26">oocysts are hardy</a>, thick-walled and resistant to chlorine and acid. They are not destroyed by chlorine at the normal concentrations found in swimming pools. </p>
<p>We also know oocysts can be <a href="https://wwwnc.cdc.gov/eid/article/5/4/99-0425_article">significantly protected</a> from the effects of chlorine in swimming pools by faecal material, so the presence of even small amounts of faecal matter contaminated with <em>Cryptosporidium</em> in a swimming pool would necessitate closure and a thorough decontamination. </p>
<p>Young children and in particular children in nappies are known to increase the potential for disease transmission in recreational water. Proper nappy changing, frequent bathroom breaks and showering before swimming to remove faecal residue are helpful ways to reduce the risk. </p>
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<img alt="Two children playing in a body of water." src="https://images.theconversation.com/files/575749/original/file-20240214-26-4wbfib.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/575749/original/file-20240214-26-4wbfib.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/575749/original/file-20240214-26-4wbfib.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/575749/original/file-20240214-26-4wbfib.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/575749/original/file-20240214-26-4wbfib.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/575749/original/file-20240214-26-4wbfib.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/575749/original/file-20240214-26-4wbfib.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Cryptosporidium can spread in other bodies of water, not just swimming pools.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/happy-summertime-healthy-childhood-concept-two-460928809">Yulia Simonova/Shutterstock</a></span>
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<h2>Some sensible precautions</h2>
<p>Other measures you can take to reduce yours and others’ risk of cryptosporidiosis include: </p>
<ul>
<li><p>avoid swimming in natural waters such as rivers and creeks during and for at least three days after heavy rain</p></li>
<li><p>avoid swimming in beaches for at least one day after heavy rain</p></li>
<li><p>avoid drinking untreated water such as water from rivers or springs. If you need to drink untreated water, boiling it first will kill the <em>Cryptosporidium</em></p></li>
<li><p>avoid swallowing water when swimming if you can</p></li>
<li><p>if you’ve had diarrhoea, avoid swimming for at least two weeks after it has resolved</p></li>
<li><p>avoid sharing towels or linen for at least two weeks after diarrhoea has resolved</p></li>
<li><p>avoid sharing, touching or preparing food that other people may eat for at least 48 hours after diarrhoea has resolved</p></li>
<li><p>wash your hands with soap and water after going to the bathroom or before preparing food (<em>Cryptosporidium</em> is <a href="https://www.cdc.gov/parasites/crypto/resources/childcare_outbreak.pdf">not killed</a> by alcohol gels and sanitisers).</p></li>
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<p>Not all cases of diarrhoea are due to cryptosporidiosis. There are many other <a href="https://theconversation.com/explainer-what-is-gastroenteritis-and-why-cant-i-get-rid-of-it-34351">causes of infectious gastroenteritis</a> and because the vast majority of the time recovery is uneventful you don’t need to see a doctor unless very unwell. If you do suspect you may have cryptosporidiosis you can ask your doctor to refer you for a stool test.</p><img src="https://counter.theconversation.com/content/223541/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vincent Ho does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The infection is spread by spores called oocysts in the stools of humans and animals.Vincent Ho, Associate Professor and clinical academic gastroenterologist, Western Sydney UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2234612024-02-14T01:12:59Z2024-02-14T01:12:59ZA secret war between cane toads and parasitic lungworms is raging across Australia<p>When the first cane toads were brought from South America to Queensland in 1935, many of the parasites that troubled them were left behind. But deep inside the lungs of at least one of those pioneer toads lurked small nematode lungworms.</p>
<p>Almost a century later, the toads are evolving and spreading across the Australian continent. In <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2023.2403">new research</a> published in Proceedings of the Royal Society B, we show that the lungworms too are evolving: for reasons we do not yet understand, worms taken from the toad invasion front in Western Australia are better at infecting toads than their Queensland cousins.</p>
<h2>An eternal arms race</h2>
<p>Nematode lungworms are tiny threadlike creatures that live in the lining of a toad’s lung, suck its blood, and release their eggs through the host’s digestive tract. The larva that hatch in the toad’s droppings lie in wait for a new host to pass by, then penetrate through its skin and migrate through the amphibian’s body to find the lungs and settle into a comfortable life, and begin the cycle anew.</p>
<p>Parasites and their hosts are locked into an eternal arms race. Any characteristic that makes a parasite better at finding a new host, setting up an infection, and defeating the host’s attempts to destroy it, will be favoured by natural selection. </p>
<p>Over generations, parasites get better and better at infecting their hosts. But at the same time, any new trick that enables a host to detect, avoid or repel the parasites is favoured as well. </p>
<p>So it’s a case of parasites evolving to infect, and hosts evolving to defeat that new tactic. Mostly, parasites win because they have so many offspring and each generation is very short. As a result, they can evolve new tricks faster than the host can evolve to fight them. </p>
<h2>The march of the toads</h2>
<p>The co-evolution between hosts and parasites is most in sync among the ones in the same location, because they encounter each other most regularly. A parasite is usually better able to <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1461-0248.2007.01028.x">infect hosts from the local population</a> it encounters regularly than those from a distant population.</p>
<p>But when hosts invade new territory, it can play havoc with the evolutionary matching between local hosts and parasites. </p>
<p>Since cane toads were released into the fields around Cairns in 1935, the toxic amphibians have hopped some 2,500 kilometres westwards and are currently on the doorstep of Broome. And they have <a href="https://www.nature.com/articles/439803a">changed dramatically</a> along the way. </p>
<p>The Queensland toads are homebodies and spend their lives in a small area, often reusing the same shelter night after night. As a result, their populations can build up to high densities. </p>
<p>For a lungworm larva, having lots of toads in a small area, reusing and sharing shelter sites, makes it simple to find a new host. But at the invasion front (currently in Western Australia), <a href="https://www.publish.csiro.au/wr/WR08021">toads are highly mobile</a>, moving over a kilometre per night when conditions permit, and rarely spending two nights in the same place. </p>
<p>At the forefront of the invasion, toads are few and far between. A lungworm larva at the invasion front, waiting in the soil for a toad to pass by, will have <a href="https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/09-0530.1">few opportunities</a> to encounter and infect a new host. </p>
<h2>Lungworms from the invasion front</h2>
<p>When hosts are rare, we expect the parasite will evolve to get better at infecting the ones it does encounter, because it is unlikely to get a second chance.</p>
<p>To understand how this co-evolution is playing out between cane toads and their lungworms, we did some experiments pairing hosts and parasites from different locations in Australia. What would happen when toad and lungworm strains that had been separated by 90 years of invasion were reintroduced to each other?</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/is-toadzilla-a-sign-of-enormous-cane-toads-to-come-its-possible-toads-grow-as-large-as-their-environment-allows-195929">Is 'Toadzilla' a sign of enormous cane toads to come? It's possible – toads grow as large as their environment allows</a>
</strong>
</em>
</p>
<hr>
<p>To study this we collected toads from different locations, bred them in captivity and reared the offspring in the lab under common conditions. We then exposed them to 50 lungworm larvae from a different area of the range, waited four months for infections to develop, then killed the toads and counted how many adult worms had successfully established in their lungs.</p>
<p>As expected, worms from the invasion front were best at infecting toads, not just their local ones. Behind the invasion front, in intermediate and old populations we found that hosts were able to fight their local parasites better than those from distant populations. </p>
<p>While we saw dramatic differences in infection outcomes, we have yet to determine what biochemical mechanisms caused the differences and how changes in genetic variation of host and parasite populations might have shaped them. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/in-the-evolutionary-arms-race-between-cane-toads-and-lungworms-skin-secretions-play-a-surprising-role-163821">In the evolutionary arms race between cane toads and lungworms, skin secretions play a surprising role</a>
</strong>
</em>
</p>
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<img src="https://counter.theconversation.com/content/223461/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lee A Rollins receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Rick Shine receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Greg Brown does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Cane toads are evolving as they spread across Australia. Parasitic lungworms are becoming more infectious to keep up.Greg Brown, Postdoctoral researcher, Macquarie UniversityLee A Rollins, Scientia Associate Professor, UNSW SydneyRick Shine, Professor in Evolutionary Biology, Macquarie UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2169752024-02-06T13:29:24Z2024-02-06T13:29:24ZPerils of pet poop – so much more than just unsightly and smelly, it can spread disease<figure><img src="https://images.theconversation.com/files/571526/original/file-20240125-23-k5liyr.jpg?ixlib=rb-1.1.0&rect=16%2C37%2C959%2C684&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Responsible pet owners are on diligent poop patrol.</span> <span class="attribution"><span class="source">Hannah Sussman</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Have you ever been out on a walk and as you take that next step, you feel the slippery squish of poop under your foot?</p>
<p>It’s not just gross. Beyond the mess and the smell, it’s potentially infectious. That’s why signs reminding pet owners to “curb your dog” and scoop their poop have been joined in some places by posted warnings that pet waste can spread disease.</p>
<p><a href="https://scholar.google.com/citations?user=QiTnXH8AAAAJ&hl=en&oi=ao">As a small-animal primary care veterinarian</a>, I deal with the diseases of dog and cat poop on a daily basis. Feces represent potential <a href="https://www.britannica.com/science/zoonotic-disease">zoonotic hazards</a>, meaning they can transmit disease from the animals to people.</p>
<p>The reality is that waste left to wash into the soil, whether in a neighborhood, trail or dog park, <a href="https://pubmed.ncbi.nlm.nih.gov/28316698/">can spread life-threatening</a> <a href="https://www.cdc.gov/parasites/transmission/index.html">parasites</a> not just among dogs and cats, but also <a href="https://doi.org/10.1128/spectrum.02532-21">to wild animals</a> and <a href="https://www.cdc.gov/parasites/transmission/index.html#animal">people of all ages</a>. A 2020 study found <a href="https://doi.org/10.1186/s13071-020-04147-6">intestinal parasites in 85% of off-leash dog parks</a> across the United States.</p>
<p>While human diseases caused by soil-transmitted parasites are considered uncommon in the U.S., they infect as many as an <a href="https://www.cdc.gov/parasites/ascariasis/index.html">estimated billion people worldwide</a>. Signs that remind you to pick up after your pet are not just trying to keep public spaces clean; they’re urging you to help safeguard your community’s health.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/571223/original/file-20240124-27-qinn2d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="bottom of a child's foot showing open lesions by the toes" src="https://images.theconversation.com/files/571223/original/file-20240124-27-qinn2d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/571223/original/file-20240124-27-qinn2d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=395&fit=crop&dpr=1 600w, https://images.theconversation.com/files/571223/original/file-20240124-27-qinn2d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=395&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/571223/original/file-20240124-27-qinn2d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=395&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/571223/original/file-20240124-27-qinn2d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=496&fit=crop&dpr=1 754w, https://images.theconversation.com/files/571223/original/file-20240124-27-qinn2d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=496&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/571223/original/file-20240124-27-qinn2d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=496&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Parasites can enter your body through broken skin and set up shop, as in this hookworm infection.</span>
<span class="attribution"><a class="source" href="https://phil.cdc.gov/Details.aspx?pid=5204">CDC</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Abandoned poop’s impact on people</h2>
<p>Common dog poop parasites include <a href="http://www.cdc.gov/parasites/resources/roundworms_hookworms.html">hookworms, roundworms</a>, <a href="https://www.britannica.com/science/coccidium">coccidia</a> and <a href="https://www.britannica.com/animal/whipworm">whipworms</a>. Hookworms and roundworms can thrive in a variety of species, including humans.</p>
<p>Their microscopic larvae can get into your body through small scratches in your skin after contact with contaminated soil or via accidental oral ingestion. Remember that next time you’re outside and wipe sweat from your face with a dirty hand and then lick your lips or take a drink – it’s that simple. After hose or rain water has rinsed contaminated poop into the soil, these parasite eggs can <a href="https://www.cdc.gov/parasites/toxocariasis/epi.html">survive and infect for months or years</a> to come.</p>
<p>Once in the human body, both hookworm and roundworm larvae can mature and migrate through the bloodstream into the lungs. From there, coughs help them gain access to <a href="https://www.merckmanuals.com/home/infections/parasitic-infections-nematodes-roundworms/hookworm-infection">the digestive tract of their host</a>, where they leach nutrients by attaching to the intestinal wall. People with healthy immune systems may show no clinical signs of infection, but in sufficient quantities these parasites <a href="https://www.cdc.gov/parasites/hookworm/disease.html">can lead to anemia and malnourishment</a>. They can even <a href="https://doi.org/10.1016/j.revmed.2015.12.023">cause an intestinal obstruction</a> which may require surgical intervention, especially in young children.</p>
<p>Additionally, larval stages of roundworms <a href="https://doi.org/10.1016/bs.apar.2020.01.001">can move into the human eye</a> and, in rare cases, <a href="https://www.cdc.gov/parasites/toxocariasis/disease.html">lead to permanent blindness</a>. Hookworms can create a <a href="https://www.cdc.gov/parasites/zoonotichookworm/disease.html">severely itchy condition called cutaneous larva migrans</a> <a href="https://wwwnc.cdc.gov/travel/yellowbook/2024/infections-diseases/cutaneous-larva-migrans">as the larval worm moves</a> just under the skin of its host.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/571669/original/file-20240126-27-e6h7di.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="about a dozen little white worms next to a wooden match" src="https://images.theconversation.com/files/571669/original/file-20240126-27-e6h7di.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/571669/original/file-20240126-27-e6h7di.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/571669/original/file-20240126-27-e6h7di.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/571669/original/file-20240126-27-e6h7di.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/571669/original/file-20240126-27-e6h7di.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/571669/original/file-20240126-27-e6h7di.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/571669/original/file-20240126-27-e6h7di.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Adult hookworms.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/adult-hookworms-of-a-dog-in-the-institute-for-parasitology-news-photo/162781943">Agency-Animal-Picture via Getty Images</a></span>
</figcaption>
</figure>
<p>Once the parasite’s life cycle is complete, it may exit the host’s body as an intact adult worm, which looks like a small piece of cooked spaghetti.</p>
<h2>The impact on other animals</h2>
<p><a href="https://doi.org/10.1016/s0195-5616(87)50005-5">Dogs and cats can also develop</a> the same symptoms people do due to parasitic infections. In addition to risks of hookworms and roundworms, pets are also vulnerable to whipworm, giardia and coccidia.</p>
<p>Beyond parasites, unattended poop may also be contaminated with canine or feline viruses, <a href="https://doi.org/10.1016/j.vetmic.2020.108760">such as parvovirus</a>, <a href="https://doi.org/10.1016/B0-72-160422-6/50016-4">distemper virus and canine coronavirus</a>, that can create life-threatening disease in other dogs and cats, especially in adult animals that are unvaccinated and puppies and kittens.</p>
<p><a href="https://www.avma.org/resources-tools/pet-owners/petcare/canine-distemper">These viruses</a> <a href="https://www.avma.org/resources-tools/pet-owners/petcare/canine-parvovirus">attack rapidly dividing cells</a>, in particular the intestinal lining and bone marrow, leaving them unable to absorb nutrients appropriately and unable to produce replacement red and white blood cells that help defend against these and other viruses. Vaccination can protect pets.</p>
<p>Many species of local wildlife are within the canid and felid family groups. They, too, are susceptible to many of the same parasites and viruses as pet dogs and cats – while being much less likely to have received the benefit of vaccinations. Coyotes, wolves, foxes, raccoons, minks and bobcats are <a href="https://cwhl.vet.cornell.edu/disease/parvovirus#:%7E:text=Parvoviruses%20are%20capable%20of%20infecting,infect%20domestic%20cats%20and%20dogs">at risk of contracting parvovirus</a>, coronavirus <a href="https://vtfishandwildlife.com/learn-more/living-with-wildlife/wildlife-diseases/canine-distemper">and distemper</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/571667/original/file-20240126-15-giuwd9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="person dropping a bag of dog poop into bin with dog watching" src="https://images.theconversation.com/files/571667/original/file-20240126-15-giuwd9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/571667/original/file-20240126-15-giuwd9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/571667/original/file-20240126-15-giuwd9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/571667/original/file-20240126-15-giuwd9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/571667/original/file-20240126-15-giuwd9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/571667/original/file-20240126-15-giuwd9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/571667/original/file-20240126-15-giuwd9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Be prepared to deal with poop on every walk.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/teenager-putting-a-filled-biodegradable-dog-poop-royalty-free-image/1335287112">Elva Etienne/Moment via Getty Images</a></span>
</figcaption>
</figure>
<h2>Responsible pet poop management</h2>
<p>So, wherever your dog or cat relieves himself – at the park, in the woods, on the sidewalk, or even in your yard – pick up that poop but always avoid contact with your skin. It’s safest to use a shovel to place the poop directly into a plastic bag, or put a baggie over your hand to grab the poop and then pull the plastic bag over it. While it’s tempting to leave the “soft-serve” or watery poops behind, these are often the more likely culprits for spreading diseases.</p>
<p>Tie up the bag and make sure to place it in a trash can – not on top – to avoid inadvertent contamination of a neighbor or sanitation worker. Promptly <a href="https://www.cdc.gov/handwashing/when-how-handwashing.html">wash your hands</a>, particularly before touching your face or eating or drinking. Hand sanitizers can take care of many viruses on your skin, but they <a href="https://doi.org/10.3347/kjp.2016.54.1.103">won’t kill parasite eggs</a>.</p>
<p>Other potential sources of poop – and parasite – exposure are the <a href="https://doi.org/10.1155/1994/786090">sandbox, beaches and park sand</a> found under and around playgrounds. Sand is comfortable to lounge on, fun to construct into castles, and softens the impact if you fall off a play structure. But cats and other small mammals love to use it as a litter box since it’s easy to dig and absorbs moisture. Covering sandboxes when not in use and closely monitoring your environment at the beach and playground are key steps toward minimizing the risks of exposure for everyone.</p>
<p>By <a href="https://capcvet.org/guidelines">keeping your pets on regular parasite prevention</a> protocols, with annual testing for intestinal parasites and routine removal of fecal material from the environment, you can help to minimize the potential for these diseases among all the mammals in your environment – human, pet and wild.</p>
<p>Key points to remember to avoid parasites and minimize the impact on your ecosystem:</p>
<ul>
<li>Pick waste up and safely throw it out regardless of where your pet poops. Sanitize your hands afterward.</li>
<li>Wash your hands before eating or touching your face while gardening or working in the yard.</li>
<li>Avoid rinsing poop into the soil. Using rain or a garden hose only removes the visible mess, not the microscopic issues.</li>
<li>Make sure sandboxes are covered when not in use.</li>
<li>Keep your pets on <a href="https://capcvet.org/guidelines">monthly intestinal parasite deworming</a> schedules.</li>
<li>Have your vet test your pet’s poop annually for intestinal parasites.</li>
</ul><img src="https://counter.theconversation.com/content/216975/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Julia Wuerz does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The signs that remind you to pick up after your pet are not just trying to keep public spaces clean; they’re urging you to help safeguard your community’s health.Julia Wuerz, Clinical Assistant Professor of Small Animal Clinical Sciences, University of FloridaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2180402023-12-24T20:53:29Z2023-12-24T20:53:29ZAt a time of giving and receiving, our many Australian mistletoes do it too<figure><img src="https://images.theconversation.com/files/565345/original/file-20231212-15-jqycxu.jpg?ixlib=rb-1.1.0&rect=0%2C258%2C3264%2C2184&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Drooping mistletoe (Amyema pendula) in flower.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/31031835@N08/3235484073">John Tann/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>The airwaves and shopping centres have been filled with Christmas songs and carols. Apparently mommy was seen kissing Santa underneath the mistletoe. Harry Potter’s first kiss was also under a twining white-flowered mistletoe.</p>
<p>Magic, mystery and symbolism surround mistletoes. Their popularity at Christmas comes from their evergreen foliage symbolising life without end. </p>
<p>The festive traditions relate to the English mistletoe, <em>Viscum album</em>, and American mistletoe, <em>Phoradendron leucarpum</em>. These traditions may not apply to our species, but the mystery and magic certainly do. </p>
<p>Australia has <a href="https://blog.publish.csiro.au/australian-mistletoes/">nearly 100 species</a> of mistletoes – 75 of them in the plant family Loranthaceae – which are not to be confused with the northern hemisphere species. They occur across the country, except in Tasmania. They are parasitic plants, though for many species their biology is not fully understood.</p>
<p>My interest in mistletoes stems from the many native species that live on common trees such as eucalypts, elms, plane trees, liquidambars, oaks and common fruit trees. Being parasites, mistletoes have often been seen as receivers or even takers, rather than givers, which is hardly in the spirit of the festive season. However, <a href="https://www.annualreviews.org/doi/abs/10.1146/annurev-ecolsys-102320-115331">recent research</a> has revealed they are givers too! </p>
<figure class="align-center ">
<img alt="a traditional Christmas card from around 1910 showing white-berried mistletoe, red-berried holly and gold bells" src="https://images.theconversation.com/files/564449/original/file-20231208-23-jfdagi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/564449/original/file-20231208-23-jfdagi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/564449/original/file-20231208-23-jfdagi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/564449/original/file-20231208-23-jfdagi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/564449/original/file-20231208-23-jfdagi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=472&fit=crop&dpr=1 754w, https://images.theconversation.com/files/564449/original/file-20231208-23-jfdagi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=472&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/564449/original/file-20231208-23-jfdagi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=472&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Traditional Christmas mistletoes, as shown on this early 20th-century card, are the white-berried American and English species.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/ironrodart/4172489684/in/photolist-7mH6Pj-cAyv-6q6q6C">Royce Bair/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
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<strong>
Read more:
<a href="https://theconversation.com/how-we-brought-mistletoes-back-to-the-trees-of-melbourne-while-warding-off-hungry-possums-211742">How we brought mistletoes back to the trees of Melbourne – while warding off hungry possums</a>
</strong>
</em>
</p>
<hr>
<h2>The mystery and magic of our mistletoes</h2>
<p>Indigenous communities were <a href="https://www.australiangeographic.com.au/topics/science-environment/2018/11/australia-is-the-real-home-of-mistletoe/">well aware</a> of the sweet sticky fruits and the medicinal benefits certain mistletoe species provided. They also used mistletoes as a general indicator of the condition of Country and as part of fire management. Some may have used the foliage in their cleansing and welcome ceremonies too.</p>
<p>You may be thinking it’s a mystery why you haven’t noticed these plants more often. That’s explained by a bit of mistletoe magic. </p>
<p>Many of our species have a brilliant camouflage. Their leaves mimic those of the host tree (a phenomenon called crypsis). So mistletoes such as <em>Amyema miguelli</em> and <em>A. pendula</em> have leaves that resemble those of eucalypts, but they become conspicuous when they flower.</p>
<p>Mistletoes are hemi-parasites, which means they have green leaves and photosynthesise like other plants, but take water and nutrients from their hosts. They do this by tapping into the transport system inside the host plant and diverting some of the water and nutrients it contains. </p>
<figure class="align-center ">
<img alt="Clumps of mistletoe growing on a eucalypt in the bush" src="https://images.theconversation.com/files/565350/original/file-20231212-23-n95ls7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/565350/original/file-20231212-23-n95ls7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/565350/original/file-20231212-23-n95ls7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/565350/original/file-20231212-23-n95ls7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/565350/original/file-20231212-23-n95ls7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/565350/original/file-20231212-23-n95ls7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/565350/original/file-20231212-23-n95ls7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Mistletoe leaves can look a lot like those of their host, such as this box mistletoe (<em>Amyema miquelii</em>) on a yellow box (<em>Eucalyptus melliodora</em>) tree.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/arthur_chapman/8257154832">Arthur Chapman/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/mistletoe-famous-for-stolen-holiday-kisses-is-a-parasite-that-steals-water-and-nutrients-from-other-plants-173555">Mistletoe – famous for stolen holiday kisses – is a parasite that steals water and nutrients from other plants</a>
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</em>
</p>
<hr>
<h2>So what do they give back?</h2>
<p>Mistletoes shed more leaves more often than other plants of comparable size. These leaves contain valuable elements and compounds. This shedding creates a litter layer and compost that <a href="https://www.abc.net.au/everyday/the-misunderstood-magical-mistletoes-of-australia/11505510">enriches the soil and increases the biodiversity</a> not only in the soil but in the environment around them. </p>
<p>It isn’t just other plants that <a href="https://www.annualreviews.org/doi/abs/10.1146/annurev-ecolsys-102320-115331">benefit from these gifts</a>. The numbers of different insects, spiders and fungi present in the leaf litter goes up significantly where mistletoes are present. So too does the diversity of birds and other animals.</p>
<p>Many native mistletoes have spectacular and colourful flowers. These are an important source of food for many insect and bird species. </p>
<p>This means mistletoes are important for the biodiversity of the ecosystems that contain them.</p>
<p>There is more mistletoe magic! Mistletoes often have a dense foliage, which creates a cooler microclimate in their vicinity. Mistletoes also continue to transpire water when other plants have ceased due to dry conditions, which further cools the air. </p>
<p>There is <a href="https://www.annualreviews.org/doi/abs/10.1146/annurev-ecolsys-102320-115331">evidence </a> that birds and mammals nest in the denser cooler mistletoe foliage in preference to other more abundant plants growing around them. Animals also take refuge within and under mistletoes when it’s very hot. This benefit for native wildlife may be all the greater as climate changes.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/mistletoe-the-kiss-of-life-for-healthy-forests-52137">Mistletoe: the kiss of life for healthy forests</a>
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</em>
</p>
<hr>
<h2>Too many mistletoes can harm their host</h2>
<p>We tend to notice mistletoes when flowering and bird feeding peak, or when their evergreen foliage stands out against the bare branches of deciduous host trees. We can then be surprised at how many mistletoes are growing in the canopy of a tree in our garden.</p>
<p>In some parts of Australia, the number of mistletoes can increase over time such that large numbers on a single host can sap the tree’s vigour. Branches beyond the point of mistletoe attachment die back, particularly on older trees and in drier seasons. When there are more than 20 mistletoes per tree, both its <a href="https://joa.isa-arbor.com/article_detail.asp?JournalID=1&VolumeID=46&IssueID=2&ArticleID=3502">growth rate and flowering are reduced</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/564454/original/file-20231208-15-22yb4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/564454/original/file-20231208-15-22yb4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/564454/original/file-20231208-15-22yb4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=428&fit=crop&dpr=1 600w, https://images.theconversation.com/files/564454/original/file-20231208-15-22yb4u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=428&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/564454/original/file-20231208-15-22yb4u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=428&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/564454/original/file-20231208-15-22yb4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=538&fit=crop&dpr=1 754w, https://images.theconversation.com/files/564454/original/file-20231208-15-22yb4u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=538&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/564454/original/file-20231208-15-22yb4u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=538&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This large eucalyptus tree is heavily infested with mistletoes.</span>
<span class="attribution"><a class="source" href="https://www.anbg.gov.au/index.html">M. Fagg/Australian National Botanic Gardens</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>In hot dry conditions, high mistletoe numbers can lead to the deaths of older, stressed trees. Changes to fire regimes and the clearing of native vegetation are likely causes of increased mistletoe infestation.</p>
<p>For your garden trees, some appropriate mistletoe control may benefit not only your trees but the mistletoes too. Mistletoe control requires a sophisticated approach because of their importance for local ecosystems. </p>
<p>A large tree with a full canopy in good condition can cope with about four to six mistletoes. Survey mature trees to ascertain mistletoe numbers and take steps to control some, but not all, of the mistletoes if infestations are excessive. </p>
<p>To remove mistletoe, cut the connection to the host tree as close as possible to the branch or trunk without damaging the host. In some cases there may be more than one connection and so several cuts may be required. Sometimes nature will take control as mistletoes can die from excessive <a href="https://auf.isa-arbor.com/content/46/2/135">water loss during heatwaves</a>. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/an-unexpected-consequence-of-climate-change-heatwaves-kill-plant-pests-and-save-our-favourite-giant-trees-148919">An unexpected consequence of climate change: heatwaves kill plant pests and save our favourite giant trees</a>
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</p>
<hr>
<figure class="align-center ">
<img alt="Composite image of the cherry ballart (Exocarpos cupressiformis) and the Western Australian Christmas tree (Nuytsia floribunda)." src="https://images.theconversation.com/files/565354/original/file-20231212-16-mevwjv.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/565354/original/file-20231212-16-mevwjv.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/565354/original/file-20231212-16-mevwjv.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/565354/original/file-20231212-16-mevwjv.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/565354/original/file-20231212-16-mevwjv.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/565354/original/file-20231212-16-mevwjv.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/565354/original/file-20231212-16-mevwjv.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=471&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Australia has two native mistletoes associated with Christmas: the cherry ballart (<em>Exocarpos cupressiformis</em>) and the Western Australian Christmas tree (<em>Nuytsia floribunda</em>).</span>
<span class="attribution"><span class="source">John Tann/Flickr, Grame Churchard/Wikimedia Commons</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>A home-grown Christmas tradition</h2>
<p>Not all mistletoes grow in tree canopies. Some are root parasites. They include the cherry ballart, <em>Exocarpos cuppressiformis</em>, and the spectacular Western Australian Christmas tree, <em>Nuytsia floribunda</em>. </p>
<p>The latter is renowned for its abundant brilliant yellow-orange flowers over the Christmas period. Early settlers used the cherry ballart with its conifer-like foliage as a Christmas tree with or without its red “cherries” as decoration. The “cherries” are not true fruits, but swollen fruit stalks - another bit of mistletoe magic and mystery.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/was-christmas-tree-what-mungee-the-worlds-largest-mistletoe-can-teach-us-about-treading-lightly-205568">'WA's Christmas tree': what mungee, the world's largest mistletoe, can teach us about treading lightly</a>
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</em>
</p>
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<img src="https://counter.theconversation.com/content/218040/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gregory Moore does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Australia has nearly 100 mistletoe species and they’re the source of plenty of magic and mystery. We even have a couple with their own home-grown associations with Christmas.Gregory Moore, Senior Research Associate, School of Ecosystem and Forest Sciences, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2134602023-11-23T19:02:31Z2023-11-23T19:02:31ZDrug resistance may make common infections like thrush untreatable<p><em>Antimicrobial resistance is <a href="https://www.who.int/news-room/fact-sheets/detail/antimicrobial-resistance">one of the biggest global threats</a> to health, food security and development. This month, The Conversation’s experts <a href="https://theconversation.com/au/topics/the-dangers-of-antibiotic-resistance-146983">explore how we got here and the potential solutions</a>.</em></p>
<hr>
<p>We’ve all heard about antibiotic resistance. This happens when bacteria develop strategies to avoid being destroyed by an antibiotic. </p>
<p>The consequences of antibiotic resistance mean an antibiotic previously used to cure bacterial infections no longer works effectively because the bacteria have become resistant to the drug. This means it’s getting harder to cure the infections some bacteria cause.</p>
<p>But unfortunately, it’s only one part of the problem. The same phenomenon is also happening with other causes of infections in humans: fungi, viruses and parasites.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-rise-and-fall-of-antibiotics-what-would-a-post-antibiotic-world-look-like-213450">The rise and fall of antibiotics. What would a post-antibiotic world look like?</a>
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<p>“Antimicrobial resistance” means the drugs used to treat diseases caused by microbes (bugs that cause infection) no longer work. This occurs with antibacterial agents used against bacteria, antifungal agents used against fungi, anti-parasitic agents used against parasites and antiviral agents used against viruses.</p>
<p>This means a wide range of previously controllable infections are becoming difficult to treat – and may become untreatable. </p>
<h2>Fighting fungi</h2>
<p>Fungi are responsible for a range of infections in humans. Tinea, ringworm and vulvovaginal candidiasis (thrush) are some of the more familiar and common superficial fungal infections. </p>
<p>There are also life-threatening fungal infections such as aspergillosis, cryptococcosis and invasive fungal bloodstream infections including those caused by <em>Candida albicans</em> and <em>Candida auris</em>. </p>
<p>Fungal resistance to antifungal agents is a problem for several reasons. </p>
<p>First, the range of antifungal agents available to treat fungal infections is limited, especially compared to the range of antibiotics available to treat bacterial infections. There are only four broad families of antifungal agents, with a small number of drugs in each category. Antifungal resistance further restricts already limited options.</p>
<p>Life-threatening fungal infections happen less frequently than life-threatening bacterial infections. But they’re rising in frequency, especially among people whose immune systems are compromised, including by <a href="https://7news.com.au/news/qld/first-heart-transplant-patient-to-die-from-fungal-infection-at-brisbanes-prince-charles-hospital-identified-as-mango-hill-gp-muhammad-hussain-c-12551559">organ transplants</a> and chemotherapy or immunotherapy for cancer. The threat of getting a drug-resistant fungal infection makes all of these health interventions riskier.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-do-candida-auris-and-other-fungi-develop-drug-resistance-a-microbiologist-explains-203495">How do _Candida auris_ and other fungi develop drug resistance? A microbiologist explains</a>
</strong>
</em>
</p>
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<p>The greatest <a href="https://www.frontiersin.org/articles/10.3389/fimmu.2017.00735/full">burden of serious fungal disease</a> occurs in places with limited health-care resources available for diagnosing and treating the infections. Even if infections are diagnosed and antifungal treatment is available, antifungal resistance reduces the treatment options that will work.</p>
<p>But even in Australia, common fungal infections are impacted by resistance to antifungal agents. Vulvovaginal candidiasis, known as thrush and caused by <em>Candida</em> species and some closely related fungi, is usually reliably treated by a topical antifungal cream, sometimes supplemented with an oral tablet. However, instances of <a href="https://www.theage.com.au/national/victoria/they-can-t-sit-properly-doctors-treat-growing-number-of-women-with-chronic-thrush-20230913-p5e499.html">drug-resistant thrush</a> are increasing, and new treatments are needed.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1584939012753862657"}"></div></p>
<h2>Targeting viruses</h2>
<p>Even <a href="https://theconversation.com/why-are-there-so-many-drugs-to-kill-bacteria-but-so-few-to-tackle-viruses-137480">fewer antivirals</a> are available than antibacterial and antifungal agents. </p>
<p>Most antimicrobial treatments work by exploiting differences between the microbe causing the infection and the host (us) experiencing the infection. Since viruses use our cells to replicate and cause their infection, it’s difficult to find antiviral treatments that selectively target the virus without damaging us. </p>
<p>With so few antiviral drugs available, any resistance that develops to one of them significantly reduces the treatment options available. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-are-there-so-many-drugs-to-kill-bacteria-but-so-few-to-tackle-viruses-137480">Why are there so many drugs to kill bacteria, but so few to tackle viruses?</a>
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<hr>
<p>Take COVID, for example. Two antiviral medicines are in widespread use to treat this viral infection: Paxlovid (containing nirmatrelvir and ritonavir) and Lagevrio (molnupiravir). So far, SARS-CoV-2, the virus that causes COVID, has not developed significant resistance to either of these <a href="https://www.cidrap.umn.edu/covid-19/low-levels-resistance-paxlovid-seen-sars-cov-2-isolates">treatments</a>. </p>
<p>But if SARS-CoV-2 develops resistance to either one of them, it halves the treatment options. Subsequently relying on one would likely lead to its increased use, which may heighten the risk that resistance to the second agent will develop, leaving us with no antiviral agents to treat COVID. </p>
<p>The threat of antimicrobial resistance makes our ability to treat serious COVID infections rather precarious.</p>
<h2>Stopping parasites</h2>
<p>Another group of microbes that cause infections in humans are single-celled microbes such as <em>Plasmodium</em>, <em>Giardia</em>, <em>Leishmania</em>, and <em>Trypanosoma</em>. These microbes are sometimes referred to as parasites, and they are becoming increasingly resistant to the very limited range of anti-parasitic agents used to treat the infections they cause. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/antibiotic-resistance-microbiologists-turn-to-new-technologies-in-the-hunt-for-solutions-podcast-217615">Antibiotic resistance: microbiologists turn to new technologies in the hunt for solutions – podcast</a>
</strong>
</em>
</p>
<hr>
<p>Several <em>Plasmodium</em> species cause malaria and anti-parasitic drugs have been the cornerstone of malaria treatment for decades. But their usefulness has been significantly reduced by the <a href="https://www.mmv.org/our-work/mmvs-pipeline-antimalarial-drugs/antimalarial-drug-resistance">development of resistance</a>. </p>
<p><em>Giardia</em> parasites cause an infection called giardiasis. This can resolve on its own, but it can also cause severe gastrointestinal symptoms such as diarrhea, nausea, and bloating. These microbes have <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6207226/">developed resistance</a> to the main treatments and patients infected with drug-resistant parasites can have protracted, unpleasant infections. </p>
<figure class="align-center ">
<img alt="3D illustration of Giardia lamblia protozoan" src="https://images.theconversation.com/files/559783/original/file-20231115-19-5oxysw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/559783/original/file-20231115-19-5oxysw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/559783/original/file-20231115-19-5oxysw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/559783/original/file-20231115-19-5oxysw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/559783/original/file-20231115-19-5oxysw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/559783/original/file-20231115-19-5oxysw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/559783/original/file-20231115-19-5oxysw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"><em>Giardia</em> parasites (illustrated here) cause giardiasis.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/giardia-lamblia-protozoan-causative-agent-giardiasis-1038065005">Shutterstock</a></span>
</figcaption>
</figure>
<h2>Resistance is a natural consequence</h2>
<p>Treating infections influences microbes’ evolutionary processes. Exposure to drugs that stop or kill them pushes microbes to either evolve or die. The exposure to antimicrobial agents provokes the evolutionary process, selecting for microbes that are resistant and can survive the exposure. </p>
<p>The pressure to evolve, provoked by the antimicrobial treatment, is called “selection pressure”. While most microbes will die, a few will evolve in time to overcome the antimicrobial drugs used against them. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-do-bacteria-actually-become-resistant-to-antibiotics-213451">How do bacteria actually become resistant to antibiotics?</a>
</strong>
</em>
</p>
<hr>
<p>The evolutionary process that leads to the emergence of resistance is inevitable. But some things can be done to minimise this and the problems it brings. </p>
<p>Limiting the use of antimicrobial agents is one approach. This means reserving antimicrobial agents for when their use is known to be necessary, rather than using them “just in case”.</p>
<p>Antimicrobial agents are precious resources, holding at bay many infectious diseases that would otherwise sicken and kill millions. It is imperative we do all we can to preserve the effectiveness of those that remain, and give ourselves more options by working to discover and develop new ones.</p>
<hr>
<p><em>Read the other articles in The Conversation’s series on the dangers of antibiotic resistance <a href="https://theconversation.com/au/topics/the-dangers-of-antibiotic-resistance-146983">here</a>.</em></p><img src="https://counter.theconversation.com/content/213460/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christine Carson receives funding from state and federal funding agencies, and the CUREator program, a national biotechnology incubator delivered by Brandon BioCatalyst. She has a commercial interest in companies developing diagnostic tests and preventing viral infections.</span></em></p>We’ve all heard of antibiotic resistance. The same thing is happening with other causes of infections in humans: fungi, viruses and parasites. This is making thrush and other infections hard to treat.Christine Carson, Senior Research Fellow, School of Medicine, The University of Western AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2151302023-10-31T16:47:10Z2023-10-31T16:47:10ZInfections from a diarrhoea-causing parasite are on the rise in the UK – but experts aren’t quite sure why<figure><img src="https://images.theconversation.com/files/556845/original/file-20231031-19-ze8zzp.jpg?ixlib=rb-1.1.0&rect=53%2C26%2C6000%2C3961&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Only two species of the _Cryptosporidium_ parasite cause infections in humans.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/release-sporozoites-cryptosporidium-parvum-oocyst-3d-1266578755">Kateryna Kon/ Shutterstock</a></span></figcaption></figure><p>Infections from a parasite which can cause long-lasting, severe diarrhoea has seen an “<a href="https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2023.28.43.2300538">unprecedented and ongoing</a>” surge across the UK. This increase in infections has been ongoing since mid-August.</p>
<p>Almost 500 cases of cryptosporidiosis in a week were reported at the end of September alone – five times more than the expected number for that time of year. </p>
<p>And this may just be the tip of the iceberg, as only about <a href="https://www.food.gov.uk/sites/default/files/media/document/711-1-1393_IID2_FINAL_REPORT.pdf">one-eighth of infections</a> are ever reported. </p>
<p>While cases have started to fall, they’re still well above expected numbers. And the reasons why cases are so high this year is still unknown.</p>
<h2>What is crypto?</h2>
<p>Cryptosporidiosis (sometimes called crypto) is caused by the <em>Cryptosporidium</em> parasite.</p>
<p>There are several species of <em>Cryptosporidium</em>, most of which only rarely (if ever) <a href="https://link.springer.com/article/10.1007/s00436-019-06537-x">cause disease in humans</a>. There are two species which cause infections in humans: <em>C parvum</em> and <em>C hominis</em>.</p>
<p><em>C hominis</em> almost exclusively causes <a href="https://pubmed.ncbi.nlm.nih.gov/16159658/">infections in humans</a> while <em>C parvum</em> causes infections in many different mammals – <a href="https://pubmed.ncbi.nlm.nih.gov/16159658/0">most typically cattle</a>. But there is a subgroup of <em>C parvum</em> that has <a href="https://www.nature.com/articles/s41564-019-0377-x">recently evolved</a> into a form that generally only infects humans. </p>
<p>The main symptom of crypto is watery diarrhoea that can be accompanied by stomach cramps, dehydration, vomiting, fever or weight loss. Infections last about ten days on average, which is much longer than what you’d see with <a href="https://emedicine.medscape.com/article/215490-clinical">other infections</a>, such as <em>Salmonella</em> or <em>Campylobacter</em>. </p>
<p>Crypto predominantly affects children, typically those of <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3323324/">pre-school age</a>. Children are most at risk due to their lack of immunity. </p>
<figure class="align-center ">
<img alt="A boy wearing goggles swims in a swimming pool." src="https://images.theconversation.com/files/556847/original/file-20231031-19-w7qbls.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/556847/original/file-20231031-19-w7qbls.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/556847/original/file-20231031-19-w7qbls.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/556847/original/file-20231031-19-w7qbls.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/556847/original/file-20231031-19-w7qbls.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/556847/original/file-20231031-19-w7qbls.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/556847/original/file-20231031-19-w7qbls.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Swimming may be one potential cause of the current UK outbreak.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/boy-swimming-freestyle-771049702">Michael Brin/ Shutterstock</a></span>
</figcaption>
</figure>
<h2>How do you contract it?</h2>
<p>Crypto is caused by inadvertently ingesting faecal matter. The parasite can be spread through food, water and contact with an infected person or animal. Many crypto outbreaks have been caused by people drinking water that had become contaminated by <a href="https://pubmed.ncbi.nlm.nih.gov/23247139/">human or animal faeces</a>, or consuming <a href="https://link.springer.com/article/10.1007/s15010-020-01426-3">unpasteurised milk</a> or contaminated foods – <a href="https://pubmed.ncbi.nlm.nih.gov/29122606/">typically salads</a>. </p>
<p>Outbreaks have also been associated with <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3204639/">farm visits</a>, children’s <a href="https://pubmed.ncbi.nlm.nih.gov/17768288/">day care centres</a> and even <a href="https://www.dwi.gov.uk/research/completed-research/cryptosporidium-giardia/review-of-outbreaks-of-cryptosporidiosis-in-swimming-pools/">swimming pools</a>.</p>
<p>Most people recover from crypto without needing treatment. But sometimes crypto can cause severe disease, leading to weight loss and dehydration. Infections from the <a href="https://academic.oup.com/cid/article/39/4/504/367042?login=false"><em>C hominis</em> strain</a> in particular can sometimes lead to long-term diarrhoea, irritable bowel syndrome, weight loss and fatigue. </p>
<p>People who are <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC118064/">severely immune compromised</a> – such as those with HIV/Aids or blood cancer – are also at greater risk of severe and potentially fatal infections. </p>
<p>There’s no vaccine against cryptosporidiosis. If you do catch crypto, make sure to drink plenty of water to replace lost fluids. People with more severe infections or people who are immunocompromised may be prescribed anti-parasitic drugs. While these <a href="https://emedicine.medscape.com/article/215490-treatment#d10">don’t always work</a>, they may help reduce the duration of symptoms.</p>
<h2>What is behind the current outbreak?</h2>
<p>The causes of the current surge in <em>Cryptosporidium</em> infections in the UK isn’t clear.</p>
<p>Prior to the pandemic, infections would be expected to rise in <a href="https://www.microbiologyresearch.org/content/journal/jmm/10.1099/jmm.0.001693">late summer and early autumn</a> each year. But this year, the surge is especially large. Infections have surged in <a href="https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2023.28.43.2300538">most parts of the UK</a>, indicating it’s probably not due to a localised outbreak. </p>
<p>One explanation is that this surge is due to increased exposure. </p>
<p>About two-thirds of recently reported <em>C hominis</em> cases have been linked to overseas travel – mainly Spain. Around 80% of these <em>C hominis</em> cases reported swimming in the 14 days before becoming unwell. </p>
<p>In Spain, the towns of Tarazona and Zaragoza have both reported <a href="https://promedmail.org/promed-post?place=8712372,18349">large waterborne outbreaks</a> of crypto during late summer. But whether an outbreak in a part of Spain well away from the Mediterranean beaches most tourists head for could explain this surge is doubtful. </p>
<p>This also doesn’t account for some of the cases of crypto currently being reported, as foreign travel and swimming were much less frequent in recorded <em>C parvum</em> cases.</p>
<p>Another plausible explanation for this current wave is that our immunity to crypto has fallen as a result of COVID control measures. This means the parasite is able to infect more people than would normally be the case. </p>
<p>This would make sense, as lack of immunity was implicated in the <a href="https://theconversation.com/rsv-experts-explain-why-rates-of-this-virus-are-surging-this-year-194403">high numbers of viral infections</a> seen last year. Not to mention <em>C hominis</em> infections almost disappeared during the <a href="https://www.microbiologyresearch.org/content/journal/jmm/10.1099/jmm.0.001693">first two years of the pandemic</a> due to COVID restrictions. <em>C parvum</em> infections also fell – but mainly only for the first few months after restrictions were introduced. </p>
<p>But if reduced immunity was the only explanation, then we’d expect to see increased case numbers elsewhere in Europe. Unfortunately, crypto infections are <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7900597/">inconsistently reported across Europe</a> making comparisons difficult. But among the UK’s neighbours, Ireland has certainly seen <a href="https://www.hpsc.ie/notifiablediseases/weeklyidreports/Weekly%20ID%20Report%20Week%2042%202023.pdf">more cases this year</a> than typical – even from pre-COVID years.</p>
<p>I suspect the explanation for the outbreak is a combination of the two. Reduced population immunity following a couple of years with very few infections led to increased infection rates. This then led to increased contamination of swimming pools – leading to yet more infections. </p>
<h2>How can you protect yourself?</h2>
<p>Although most infections in the current wave have been contracted while swimming, I wouldn’t encourage people to avoid swimming to protect themselves – not unless they have severe problems with immunity. But do try to avoid swallowing water while swimming. </p>
<p>If another bather has an accident in the pool, be sure to get out promptly to avoid swallowing water. Likewise, if you’re suffering from diarrhoea you should avoid swimming to protect other swimmers.</p><img src="https://counter.theconversation.com/content/215130/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul Hunter is a member of several World Health Organization Expert Advisory committees relevant to this topic and a member of a scientidic advisory committee for Suez Environment. He receives funding from National Institute of Health Reseasrch and has recevied funding from The European Interreg programme.</span></em></p>Infections from the Cryptosporidium parasite are five times higher than expected for this time of year.Paul Hunter, Professor of Medicine, University of East AngliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2147982023-10-03T19:50:49Z2023-10-03T19:50:49Z‘We could eradicate malaria by 2040’ says expert after revolutionary vaccine is approved by WHO<p><em>The World Health Organization has <a href="https://www.who.int/news/item/02-10-2023-who-recommends-r21-matrix-m-vaccine-for-malaria-prevention-in-updated-advice-on-immunization">approved</a> a new vaccine that scientists argue will be a game-changer in the fight against malaria, which kills half a million people in Africa every year. Trials have shown that the <a href="https://www.ox.ac.uk/news/2023-10-02-oxford-r21matrix-m-malaria-vaccine-receives-world-health-organization-recommendation">R21/Matrix vaccine</a>, developed by Oxford University together with the Serum Institute of India, reduces malaria by up to 75%. It can be manufactured cheaply and on a mass scale. The Conversation Weekly spoke to chief investigator Adrian Hill, who is also director of the Jenner Institute at the University of Oxford, about this revolutionary vaccine. Below are edited excerpts from the <a href="https://theconversation.com/the-long-road-to-a-new-malaria-vaccine-told-by-the-scientists-behind-the-breakthrough-podcast-214885">podcast</a>.</em></p>
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<h2>Why is the R21/Matrix vaccine a game-changer?</h2>
<p>We’re seeing about 75% efficacy by counting the reduction in numbers of malaria episodes over a year. The best vaccine prior to this was about 50% over a year, and lower than that over three years.</p>
<p>This is a material improvement, but that’s not the main improvement. The big difference is how you can manufacture it at a scale that is really needed to protect most of the children who need a malaria vaccine in Africa. </p>
<p>There are about 40 million children born every year in malaria areas in Africa who would benefit from a vaccine. Ours is a four-dose vaccine over 14 months, so you need about 160 million doses. We can achieve that. </p>
<p>The Serum Institute of India, our manufacturing and commercial partner, can produce hundreds of millions of doses of this vaccine each year, whereas the previous vaccine could be manufactured at a scale of six million doses a year from 2023 to 2026, according to Unicef reports. </p>
<p>The third real advantage of this vaccine is its cost. We were well aware that we couldn’t produce a US$100 vaccine. It wouldn’t fly for international agencies supporting the purchase and distribution of the vaccine in very low-income countries.</p>
<p>So where we are now is a price that’ll vary according to the scale, but at high volume it should be US$5 a dose.</p>
<h2>Why has developing a malaria vaccine been so difficult?</h2>
<p>People have been trying to make malaria vaccines for over 100 years. Well over 100 vaccines have gone into clinical trials in people. Very, very few have worked to any degree.</p>
<p>Malaria is not a virus, it’s not a bacterium. It’s a protozoan parasite, some thousands of times larger than a typical virus. A good measure of that is how many genes it has. Covid has 13, malaria has about 5,500. This is one of the reasons that malaria is super complex.</p>
<p>There are different parasite forms the first of which are injected by the mosquito into the skin and rapidly go to the liver. They spend a week multiplying there, and then they go into the bloodstream. And they are hugely different during these different stages. And the parasites grow at a rate of tenfold every 48 hours, multiplying furiously. </p>
<p>By the time they get to a really high parasite density, you will be very unwell. Or if you’re unlucky, you will die, typically from cerebral symptoms, a coma or from being severely anaemic. The parasites break open the red blood cells.</p>
<p>And then there’s yet another stage where the parasite changes again to a form that the mosquito can take up through its next bite and continue the life cycle by infecting somebody else.</p>
<p>So this is as complex as it gets with infectious pathogens.</p>
<p>Malaria typically goes through four life cycles and they’re all different. If you can get a really good vaccine for one of those, you will break the cycle of transmission. And that’s what we’ve been trying to do.</p>
<p>We’ve been working on targeting the so-called sporozoites, which is the form that the mosquito inoculates into your skin. We’re trying to trap it before it can get to the liver and carry on the life cycle.</p>
<p>Luckily, there are no symptoms of malaria at that stage. It’s a silent infection until it gets into the blood and starts multiplying inside your red blood cells. </p>
<p>So the sporozoite is a natural target to try and kill the parasite before it multiplies very quickly.</p>
<h2>Tell us about past attempts to develop a malaria vaccine</h2>
<p>Very early on people tried to use the whole microbe in the same way that vaccine pioneer Edward Jenner used the whole virus to inoculate against smallpox. Then the French microbiologist Louis Pasteur came along with bacterial vaccines, and so on.
In about 1943, there was a trial of the whole malaria parasite vaccine candidate in New York with zero efficacy. That put people off for a while.</p>
<p>It wasn’t until the 1980s when we could actually begin to sequence the genes in the parasite that new vaccination candidates appeared. And then within 10 years we had 5,000 candidates because everyone hoped that the gene they had sequenced might be a malaria vaccine. And of course almost all of those failed.</p>
<h2>Why aren’t vaccines for whole parasites effective against malaria?</h2>
<p>It’s the same reason that just getting infected once by malaria doesn’t give you protection against the next infection. </p>
<p>In the areas of malaria where we test our vaccines in Africa, some children get up to eight episodes in three or four months. They get quite unwell with the first and three weeks later they’re having a second bout and so on. Natural immunity doesn’t work until you’ve had a lot of different infections and that’s why adults are generally protected against malaria and don’t become very unwell. </p>
<p>The people who die of malaria in an endemic area are the <a href="https://www.who.int/news-room/fact-sheets/detail/malaria">young children </a> who may never have been infected before and die with their first infection when they’re one year old, or they might have had one or two episodes, but that wasn’t enough to give them sterilising immunity.</p>
<p>Malaria has been around for tens of millions of years. Not just in humans, but in the species that we were before we became humans.</p>
<p>It’s a very wily parasite and has developed <a href="https://academic.oup.com/femsre/article/40/2/208/2570118">immune escape mechanisms </a> of all sorts.</p>
<p>When you try to vaccinate, you suddenly find there’s some way the parasite gets around that, and it’s only when you get up to really extraordinarily high levels of antibodies that the parasite hasn’t seen before and hasn’t learnt to evolve against that it becomes effective.</p>
<h2>Will we ever eradicate malaria entirely?</h2>
<p>Malaria is very high on the list of diseases we want to eradicate. I don’t think it’s going to happen in five years or 10 years, but it should happen in something like 15 years. So 2040 would be a reasonable target. </p>
<p>Nobody’s suggesting we stop doing what we’re doing at the moment with bed nets and spraying and drugs. But now we have a new tool that may be individually more protective than any of the tools we’re using at the moment.</p><img src="https://counter.theconversation.com/content/214798/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Adrian Hill receives funding from government and charitable funders of malaria vaccine development. He has received funding awarded to the University of Oxford from the Serum Institute of India to support clinical trials of the R21/Matrix-M vaccine. He may benefit for a share of any royalty stream to Oxford University from the vaccine.</span></em></p>People have been trying to make malaria vaccines for over 100 years. With the help of the revolutionary new R21/Matrix vaccine the disease could be eradicated by 2040.Adrian Hill, Director of the Jenner Institute, University of OxfordLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2124372023-08-29T03:58:29Z2023-08-29T03:58:29ZFinding a live brain worm is rare. 4 ways to protect yourself from more common parasites<p><a href="https://www.theguardian.com/australia-news/2023/aug/28/live-worm-living-womans-brain-australia-depression-forgetfulness">News reports</a> this morning describe how shocked doctors removed a live worm from a woman’s brain in a Canberra hospital last year. The woman had previously been admitted to hospital with stomach symptoms, dry cough and night sweats and months later experienced depression and forgetfulness that led to a brain scan. </p>
<p>In the <a href="https://wwwnc.cdc.gov/eid/article/29/9/23-0351_article">case study</a> published in Emerging Infectious Diseases journal, doctors describe removing the live 8cm-long nematode (roundworm) from the brain of the 64-year-old woman who was immunosuppressed. The worm was identified as <em>O. robertsi</em> which is native to Australia, where it lives on carpet pythons. The woman may have come into contact with worm eggs via snake faeces while foraging for Warrigal greens to eat.</p>
<p>It’s important to note this is an extremely rare event and headlines about brain worms can be alarming. But there are more common parasites which can infect your body and brain. And there are ways you can minimise your risks of being infected with one. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1696138859241787734"}"></div></p>
<h2>Common parasites and how they get in</h2>
<p>Parasitic infection is extremely common. Arguably the most widespread type is pinworm (<em>Enterobius vermicularis</em> also called threadworm), which is thought to be present in <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6522669/">over a billion people</a> worldwide, especially children. Pinworms grow to around 1cm in length and are specific to human hosts. They cause intense bottom itching and get passed from person-to-person. It’s a myth that you can get it from pets.</p>
<p><a href="https://www.cdc.gov/parasites/giardia/pathogen.html#:%7E:text=Giardia%20duodenalis%20is%20a%20protozoan,Giard%20of%20Paris%20and%20Dr.">Giardia</a> (<em>Giardia duodenalis</em>) is also very common and can contaminate food, water and surfaces. This water-borne parasite is associated with poor sanitation and causes stomach symptoms like diarrhoea, cramps, bloating, nausea and fatigue. Giardia cysts (little sacs of immature parasite) spread disease and are passed out in faeces, where they can remain viable in the environment for months before being consumed by someone else. They can also be ingested via foods (such as sheep meat) that is raw or undercooked.</p>
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<strong>
Read more:
<a href="https://theconversation.com/health-check-the-low-down-on-worms-and-how-to-get-rid-of-them-36486">Health check: the low-down on 'worms' and how to get rid of them</a>
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<p><a href="https://www.cdc.gov/dpdx/hookworm/index.html">Two types</a> of hookworm – <em>Necator americanis</em> and <em>Ancylostoma duadonale</em> – are found in soil. Only <em>Ancylostoma duodenale</em> is an issue in Australia and is typically found in <a href="https://www.cdc.gov/dpdx/hookworm/index.html">remote communities</a>. </p>
<p>When a person is infected (usually via barefeet or contaminated footwear) these worms enter the bloodstream and then hit the lungs. From the bronchi in the upper lungs, they are swallowed with secretions. Once in the gut and small bowel they can <a href="https://www.who.int/news-room/fact-sheets/detail/soil-transmitted-helminth-infections#:%7E:text=Transmission,these%20eggs%20contaminate%20the%20soil.">cause anaemia</a> (low iron). This is because they are consuming nutrients and affecting iron absorption. They also release an anticoagulant that stops the human host’s blood clotting and causes tiny amounts of blood loss. </p>
<p>Fortunately, these very common parasites do not infect the brain. </p>
<p>Across the world, it’s estimated <a href="https://pubmed.ncbi.nlm.nih.gov/22491772/">30–50% of people</a> are infected with <em>Toxoplasma</em>. Most people will be asymptomatic but many carry the <a href="https://theconversation.com/one-in-three-people-are-infected-with-toxoplasma-parasite-and-the-clue-could-be-in-our-eyes-182418">signs of infection</a>. </p>
<p>The parasites can remain in the body for years as tiny tissue cysts. These cysts can be found in brain, heart and muscle. Infants can be born with serious eye or brain damage if their mothers are infected during pregnancy. People with compromised immunity – such as from AIDS or cancer treatment – are also at risk of illness from infection via pet cats or uncooked meat. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/545183/original/file-20230829-21-sm0791.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="person pats cat" src="https://images.theconversation.com/files/545183/original/file-20230829-21-sm0791.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/545183/original/file-20230829-21-sm0791.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/545183/original/file-20230829-21-sm0791.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/545183/original/file-20230829-21-sm0791.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/545183/original/file-20230829-21-sm0791.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/545183/original/file-20230829-21-sm0791.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/545183/original/file-20230829-21-sm0791.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Toxoplasmosis can be transmitted by cats.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/hand-woman-petting-brown-cat-outside-1166422114">Shutterstock</a></span>
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Read more:
<a href="https://theconversation.com/one-in-three-people-are-infected-with-toxoplasma-parasite-and-the-clue-could-be-in-our-eyes-182418">One in three people are infected with _Toxoplasma_ parasite – and the clue could be in our eyes</a>
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<h2>Then there are tapeworms and amoebas</h2>
<p>Tapeworms can infect different parts of the body including the brain. This is called <a href="https://www.cdc.gov/parasites/resources/pdf/npis_in_us_neurocysticercosis.pdf">neurocysticercosis</a> and is the leading cause of epilepsy worldwide. Neurocysticercosis is uncommon in the Western world and infection is usually via eating pork that is uncooked or prepared by someone who is infected with tapeworm (<em>Taenia solium</em>). It is more likely in locations where pigs have contact with human faeces via sewerage or waterways. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/545182/original/file-20230829-17-vqey6e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="brain scan" src="https://images.theconversation.com/files/545182/original/file-20230829-17-vqey6e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/545182/original/file-20230829-17-vqey6e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=755&fit=crop&dpr=1 600w, https://images.theconversation.com/files/545182/original/file-20230829-17-vqey6e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=755&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/545182/original/file-20230829-17-vqey6e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=755&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/545182/original/file-20230829-17-vqey6e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=949&fit=crop&dpr=1 754w, https://images.theconversation.com/files/545182/original/file-20230829-17-vqey6e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=949&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/545182/original/file-20230829-17-vqey6e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=949&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A brain scan of someone infected with pork tapeworm.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/brain-ct-cysticercosis-larva-pork-tapeworm-1619246149">Shutterstock</a></span>
</figcaption>
</figure>
<p>Tapeworm larvae can infect muscle and soft tissue. Brain tissue can provide a home for larvae because it is soft and easy to get to via blood vessels. Brain infection can cause headaches, dizziness, seizures, cognitive impairment and even dementia, due to an increase in <a href="https://www.cdc.gov/parasites/cysticercosis/gen_info/faqs.html">cerebral spinal fluid pressure</a>.</p>
<p><em><a href="https://www.cdc.gov/parasites/naegleria/general.html">Naegleria fowleri</a></em> is an amoeba found in lakes, rivers and springs in warm climates including <a href="https://www.sahealth.sa.gov.au/wps/wcm/connect/public+content/sa+health+internet/public+health/water+quality/naegleria+fowleri#:%7E:text=How%20common%20are%20Naegleria%20fowleri,frequently%20found%20in%20the%20environment.">in Australia</a>. People swimming in infected waters can have the parasite enter their body through the nose. It then travels to the brain and destroys brain tissue. The condition is <a href="https://www.cdc.gov/parasites/naegleria/general.html#:%7E:text=Top%20of%20Page-,What%20is%20the%20death%20rate%20for%20an%20infected%20person%20who,States%20from%201962%20to%202022.">almost always fatal</a>.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-are-parasites-and-how-do-they-make-us-sick-121489">What are parasites and how do they make us sick?</a>
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<h2>Yikes! 4 ways to avoid parasitic infection</h2>
<p>That all sounds very scary. And we know being infected by a snake parasite is very rare – finding one alive in someone’s brain is even rarer. But parasites are all around us. To minimise your risk of infection you can:</p>
<p><strong>1.</strong> avoid undercooked or raw pork. Freezing meat first may reduce risks (though home freezers <a href="https://www.cdc.gov/parasites/trichinellosis/prevent.html">may not get cold enough</a>) and it must be cooked to a <a href="https://www.sciencedirect.com/science/article/pii/S0924224418301560#:%7E:text=and%20time%20conditions.-,Cooking%20at%20core%20temperature%2060%E2%80%9375%20%C2%B0C%20for%2015,relied%20upon%20in%20home%20situations.">high internal temperature</a>. Avoid pork if you are travelling in places with poor sanitation</p>
<p><strong>2.</strong> avoid jumping or diving into warm fresh bodies of water, especially if they are known to carry <em>Naegleria fowleri</em>. Although only a <a href="https://www.cdc.gov/parasites/naegleria/graphs.html">handful of cases</a> are reported each year, you should assume it’s present </p>
<p><strong>3.</strong> practise good <a href="https://www.cdc.gov/handwashing/when-how-handwashing.html#:%7E:text=Follow%20Five%20Steps%20to%20Wash%20Your%20Hands%20the%20Right%20Way&text=Wet%20your%20hands%20with%20clean,for%20at%20least%2020%20seconds.">hand hygiene</a> to reduce the risk of rare and common infections. That means washing hands thoroughly and often, using soap, scrubbing for at least 20 seconds, rinsing and drying well. Clip and clean under fingernails regularly</p>
<p><strong>4.</strong> to avoid soil-borne parasites wear shoes outside, especially in rural and remote regions, wash shoes and leave them outside.</p><img src="https://counter.theconversation.com/content/212437/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vincent Ho does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Headlines about brain worms can be alarming. There are much more common parasites which can infect your body and brain and ways you can minimise your risks of being infected with one.Vincent Ho, Associate Professor and clinical academic gastroenterologist, Western Sydney UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2059262023-05-24T01:51:10Z2023-05-24T01:51:10ZAustralia is in a unique position to eliminate the bee-killing Varroa mite. Here’s what happens if we don’t<figure><img src="https://images.theconversation.com/files/527408/original/file-20230522-17-by2qo7.jpg?ixlib=rb-1.1.0&rect=57%2C23%2C3767%2C2562&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Théotime Colin</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Varroa mites – notorious honey bee parasites – have recently reached Australian shores, <a href="https://www.abc.net.au/news/rural/2022-06-24/varroa-mite-detected-at-newcastle-port/101180446">detected at the Port of Newcastle</a> in New South Wales last year. If they establish here, there would be significant implications for agricultural food security, as honey bees are heavily relied on for the pollination of many crops.</p>
<p>However, while Australia is the last continent to be invaded by the mite, it has an opportunity to be the first to eradicate it.</p>
<p><em>Varroa destructor</em> is a small mite that attaches to bees and <a href="https://www.sciencedaily.com/releases/2019/01/190114161137.htm">eats their “fat body</a>”. The fat bodies of honey bees are the insect equivalent of a liver. Varroa weakens bees, reduces their lifespan and increases the spread of deadly viruses.</p>
<p>Scientists need to be ready: this might be Australia’s best chance to collect important data on the spread and evolution of this parasite. Our new paper <a href="https://royalsocietypublishing.org/doi/10.1098/rsbl.2022.0589">published today in Biology Letters</a> outlines what questions scientists need to ask and what data they need to collect if Varroa spreads in Australia.</p>
<p>Such data could help us understand how parasites evolve, why Varroa are so damaging for honey bees, and how Varroa mites impact other insects and the environment.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-varroa-mite-the-tiny-killer-threatening-australias-bees-25710">Explainer: Varroa mite, the tiny killer threatening Australia's bees</a>
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<h2>Will Varroa establish in Australia?</h2>
<p>Australia is in close proximity to countries that have the mite, including New Zealand, Papua New Guinea, Timor-Leste and Indonesia.</p>
<p>This probably explains why invasive honey bee swarms are frequently intercepted at our ports, <a href="https://www.beeawarebrisbane.org/blog/a-brief-history-of-honey-bee-incursions-into-australia">many of these carrying Varroa</a>. Australia currently bans importation of honey bee colonies due to the biosecurity risk, so these interceptions are typically due to stowaway swarms taking up residence in shipping containers.</p>
<p>Previous invasions of Varroa have been successfully <a href="https://www.abc.net.au/news/rural/2018-06-29/varroa-mite-detected-in-melbourne/9923972">eradicated before establishing</a>, but this time Varroa circumvented the biosecurity surveillance near Newcastle and spread locally.</p>
<p>The New South Wales Department of Primary Industries has been <a href="https://www.dpi.nsw.gov.au/emergencies/biosecurity/current-situation/varroa-mite-emergency-response">contact-tracing and culling hives in contaminated areas</a>, and the spread has been slow so far. Australia has large populations of feral honey bees, which could potentially act as a reservoir for Varroa and are much harder to trace and control, so the department is tackling this with a <a href="https://www.dpi.nsw.gov.au/emergencies/biosecurity/current-situation/varroa-mite-emergency-response/wild-european-honey-bee-management">wild honey bee baiting program</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/527017/original/file-20230518-29-xsgvbi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A small red mite facing the camera on a grey metallic background, the many legs of the mites are visible as well as a few pieces of wax" src="https://images.theconversation.com/files/527017/original/file-20230518-29-xsgvbi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527017/original/file-20230518-29-xsgvbi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527017/original/file-20230518-29-xsgvbi.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527017/original/file-20230518-29-xsgvbi.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527017/original/file-20230518-29-xsgvbi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527017/original/file-20230518-29-xsgvbi.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527017/original/file-20230518-29-xsgvbi.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">A Varroa mite fallen from a hive in France.</span>
<span class="attribution"><span class="source">Théotime Colin</span>, <span class="license">Author provided</span></span>
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<h2>What threats does Varroa pose?</h2>
<p>Varroa mites are a threat to food security. Although Australia has an abundance of food and <a href="https://www.agriculture.gov.au/abares/products/insights/australian-food-security-and-COVID-19">exports it to other nations</a>, the price of food is likely to increase if Varroa escapes confinement.</p>
<p>Currently, pollination of crops in eradication zones such as <a href="https://www.abc.net.au/news/rural/2022-07-27/varroa-mite-nsw-berry-production-price-detection-coffs-harbour/101272874">berries in Coffs Harbour</a> is at risk due to the removal of all honey bees in the region, which may lead to short-term increases in food costs.</p>
<p>However, establishment and spread of Varroa will lead to lower pollination and lower crop production across the country, which will raise the price of most fruit and vegetables that depend on bee pollination.</p>
<p>This could worsen the <a href="https://www.theguardian.com/australia-news/2022/oct/17/inflation-and-inadequate-welfare-fuelling-australias-food-insecurity-crisis-foodbank-finds">food affordability crises caused by the current inflation</a>, affecting the ability of low income households to buy nutritious and fresh produce. Almond pollination has already noted a deficit of <a href="https://www.abc.net.au/news/rural/2022-07-18/victoria-to-be-80-000-bee-hives-short-for-almond-pollination/101246392">80,000 hives in the last season</a>. </p>
<p>Many of the honey bee colonies that pollinate our crops are <a href="https://theconversation.com/explainer-varroa-mite-the-tiny-killer-threatening-australias-bees-25710">thought to be feral</a>, living in tree hollows or nest-boxes designed for native animals. These feral bees are not managed by beekeepers and so won’t be saved by the use of Varroa treatments, meaning they will most likely disappear. </p>
<p>Varroa may be a threat to wild pollinators including native bees. Varroa often spreads viruses, which can jump between species and may threaten our wild native pollinators. Of particular concern are viruses that deform insect wings and cause paralysis. Fortunately, these viruses have not been detected in the current Varroa incursion.</p>
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<a href="https://images.theconversation.com/files/527330/original/file-20230520-29-w4rnrp.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration of different bee species pollinating flowers from crops and native plants" src="https://images.theconversation.com/files/527330/original/file-20230520-29-w4rnrp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527330/original/file-20230520-29-w4rnrp.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527330/original/file-20230520-29-w4rnrp.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527330/original/file-20230520-29-w4rnrp.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527330/original/file-20230520-29-w4rnrp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527330/original/file-20230520-29-w4rnrp.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527330/original/file-20230520-29-w4rnrp.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Australia currently relies on pollination by commercial honey bees (yellow), supplemented by feral honey bees (brown), though we have many native bee species like stingless bees and blue banded bees that are also being used in crop pollination.</span>
<span class="attribution"><span class="source">Boris Yagound, adapted from Chapman et al. 2023</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<h2>How can we secure Australia’s agricultural industry?</h2>
<p>Australia’s agricultural industry relies mostly on pollination by European honey bees. This choice has been risky.</p>
<p>In Europe, pollination services are also provided by diverse species like bumble bees, mining bees and mason bees (e.g. <em>Osmia rufa</em>), many of which are un-managed wild species that nest alone.</p>
<p>If Varroa escapes confinement, beekeepers will still be able to maintain colonies of honey bees but at greater costs, due to colony losses and the need for chemicals to treat Varroa mites in the hives. These costs have the potential to sink businesses, and affect the livelihoods of beekeepers. </p>
<p>Australia needs to decrease its reliance on the European honey bee in agriculture and improve pollinator diversity via the use of <a href="https://beeaware.org.au/pollination/native-bees/native-bees-as-alternative-pollinators/">other native pollinator species</a> such as native stingless bees, blue banded bees, <a href="https://www.horticulture.com.au/hort-innovation/news-events/media-releases/2022/Scientists-bring-flies-to-Varroa-Mite-Red-Zone">or even flies</a>. For example, native Australian stingless bees aid in the pollination of macadamia and capsicum crops and could be used for the pollination of other crops.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/7MILt82Y5ig?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Native blue banded bees pollinating tomatoes in Australia.</span></figcaption>
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<h2>Australia’s unique situation</h2>
<p>Australia is different from other Varroa infected regions of the world. Our incursion was smaller, it was identified early and the management zone is small enough to be feasibly eradicated.</p>
<p>Even if Varroa spreads in Australian landscapes, hopes are that the pace of the spread may be slower in Australia than it was in other regions due to the smaller incursion, the colossal eradication effort and large tracts of land that are inhospitable to honey bees. Managed honey bee populations are <a href="https://extensionaus.com.au/professionalbeekeepers/670000-registered-honey-bee-hives-in-australia/">concentrated around coastal regions</a>, or in Australia’s major rural food bowl regions where pollinator-dependant crops (such as almonds, blueberries and apples) are located. </p>
<p>This gives us a chance to prevent the spread of Varroa across inland Australia, where there are no honey bees.</p>
<p>Luckily for us, most of the world has already spent the last few decades trying to minimise Varroa mite management costs. As a nation, we now have the chance to initiate a fresh and coordinated management response. Australia could organise state-wide <a href="https://www.epa.nsw.gov.au/your-environment/pesticides/integrated-pest-management">integrated pest management</a> approaches and treatment regimes to prevent Varroa’s resistance to chemical treatments from developing rapidly.</p>
<p>In short, there are good reasons to remain positive about the future of Australian beekeeping and horticultural industries, but there is still much work for our research community to do.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/bees-can-do-so-much-more-than-you-think-from-dancing-to-being-little-art-critics-204039">Bees can do so much more than you think – from dancing to being little art critics</a>
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<img src="https://counter.theconversation.com/content/205926/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Scarlett Howard has received funding from Australian Government, RMIT University, Fyssen Foundation, L’Oreal-UNESCO, Australian Academy of Sciences, Hermon Slade, Deakin University, and Monash University. She has been affiliated with Pint of Science Australia.</span></em></p><p class="fine-print"><em><span>Alexander Mikheyev receives funding from the Australian Research Council and Agrifutures Australia. </span></em></p><p class="fine-print"><em><span>Emily Remnant has received funding from The University of Sydney, Horticulture Innovation Australia, Agrifutures Australia, the Australia and Pacific Science Foundation, the Australian Government and the NSW Government. She has volunteered for the NSW Apiarists Association.</span></em></p><p class="fine-print"><em><span>Simon Tierney has received funding from Australian Entomological Society, Centre for Biodiversity Analysis, Flinders University, Hort Innovation, National Geographic Society, Royal Entomological Society, Smithsonian Institution, Smithsonian Tropical Research Institute, The University of Adelaide, Tokyo Metropolitan University and Western Sydney University. </span></em></p><p class="fine-print"><em><span>Théotime Colin receives funding from Macquarie University, the Lord Mayor's Charitable Foundation, the Eldon & Anne Foote Trust, Hort Innovation Australia, the Innovation Connections program, the The Department of Agriculture, Water and the Environment and Agrifutures Australia. He is a member of the New South Wales Apiarists' Association.</span></em></p>Australia is the last continent to be invaded by the dangerous honey bee parasite, and has an opportunity to be the first to eradicate it.Scarlett Howard, Lecturer, School of Biological Sciences, Monash UniversityAlexander Mikheyev, Group Leader, Mikheyev Group - Evolutionary genomics, Australian National UniversityEmily Remnant, Lecturer, School of Life and Environmental Sciences, University of SydneySimon Tierney, Lecturer & Research Fellow, Western Sydney UniversityThéotime Colin, Macquarie UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2056162023-05-19T12:39:41Z2023-05-19T12:39:41ZParasitic infections hit the health of low-income Black communities where states have neglected sewage systems<figure><img src="https://images.theconversation.com/files/526852/original/file-20230517-19805-na6y4i.jpg?ixlib=rb-1.1.0&rect=230%2C579%2C5061%2C2951&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A microscopic image of a hookworm egg that can cause intestinal problems in humans.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/photomicrograph-of-a-hookworm-egg-from-an-undetermined-news-photo/901305626?adppopup=true">Smith Collection/Gado/Getty Images</a></span></figcaption></figure><p>Intestinal infections take a heavy toll on impoverished Black communities that have out-of-date sewage systems. These infections often spread through contaminated soil and water and are among the most common diseases worldwide. </p>
<p><a href="https://www.who.int/news-room/fact-sheets/detail/soil-transmitted-helminth-infections">Approximately one-quarter</a> of the global population is infected with soil-transmitted <a href="https://www.ncbi.nlm.nih.gov/books/NBK8282/">helminths</a>, intestinal parasitic worms that can cause serious health problems.</p>
<p>Additionally, <a href="https://www.ncbi.nlm.nih.gov/books/NBK534233/">up to 50%</a> of people around the world are infected with <a href="https://www.hopkinsmedicine.org/health/conditions-and-diseases/helicobacter-pylori#:%7E:text=H.%20pylori%20is%20a%20type,in%20your%20upper%20digestive%20tract."><em>Helicobacter pylori</em></a>, bacteria that live in the stomach and can cause ulcers and cancer. </p>
<p>I am <a href="https://scholar.google.com/citations?user=x_4krdIAAAAJ&hl=en">a biological anthropologist</a>, and it is clear to me that these two types of infections contribute to systemic health inequities, especially among communities of color in which <a href="https://aspe.hhs.gov/sites/default/files/documents/08307d793263d5069fdd6504385e22f8/black-americans-coverages-access-ib.pdf">limited access to medical care</a> and inadequate sanitation systems may both increase exposure to pathogens and <a href="https://blogs.biomedcentral.com/bugbitten/2015/06/23/peter-hotez-answers-questions-regarding-worm-index-blue-marble-health/">lead to worse outcomes</a>. </p>
<p>Historically, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3183777/">intestinal infections</a> have been prevalent in parts of the U.S. where high poverty rates and environmental factors – such as flooding and warm, humid summers – favor infection spread.</p>
<p>Although <a href="https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0000256&fbclid=IwAR1TGrUaZe6dAUF-bz3sOWkLkKBMeEvA6ucmld_Yb_auaP36Eg0Tr-I9gaw">many Americans believe</a> these diseases now exist only in lower-income countries, research that <a href="https://tjceponrobins.wixsite.com/research">my colleague </a> and I have conducted challenges this assumption. </p>
<h2>Renewed interest in US intestinal infections</h2>
<p>Launched in 2019, the <a href="https://www.reachresearch.org/">Rural Embodiment and Community Health Study</a> started with the goal of measuring current infection rates and determining which living conditions contribute to infection risk. </p>
<p>Though national infection rates remain unclear because of the absence of large-scale studies, our preliminary work in 2019 found that <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/ajhb.23889?casa_token=JLQ7RfziTSsAAAAA%3AGXTdG5EqJipArrMdajcVt7OGT63bDN5EKkl5nlVfTY3mnhbeec1kRR98SOfT3pMsOxZwl4-A8rJI4wc">38% of children</a> sampled in a predominantly Black Mississippi Delta community had intestinal parasitic infections.</p>
<p>Moreover, <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/ajpa.24574?casa_token=vZA-R078l4QAAAAA%3AjBOJ4G3Z3SiaIKheU0UMOFgpVRX7kEROZ0XIyzC4MtOol6y8rAY0TzPOwEM_L6TQjCoHz12ydBx-pDY">80% of those children</a> exhibited high levels of intestinal inflammation. Those levels are <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/ajpa.24574?casa_token=vZA-R078l4QAAAAA%3AjBOJ4G3Z3SiaIKheU0UMOFgpVRX7kEROZ0XIyzC4MtOol6y8rAY0TzPOwEM_L6TQjCoHz12ydBx-pDY">much higher than those observed in other populations</a> and may lead to <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/ajpa.24574">several poor health outcomes</a>, including <a href="https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0006205">impaired intestinal ability to absorb nutrients and stunted growth</a>.</p>
<p>Our more recent analyses from 2022 focused on adults living in the Mississippi Delta and Southwestern Illinois, two areas that experience regular flooding.</p>
<figure class="align-center ">
<img alt="A snakelike object is visible amid random specks." src="https://images.theconversation.com/files/526830/original/file-20230517-22090-a77b9l.jpg?ixlib=rb-1.1.0&rect=468%2C595%2C4823%2C2951&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/526830/original/file-20230517-22090-a77b9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=404&fit=crop&dpr=1 600w, https://images.theconversation.com/files/526830/original/file-20230517-22090-a77b9l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=404&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/526830/original/file-20230517-22090-a77b9l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=404&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/526830/original/file-20230517-22090-a77b9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=507&fit=crop&dpr=1 754w, https://images.theconversation.com/files/526830/original/file-20230517-22090-a77b9l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=507&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/526830/original/file-20230517-22090-a77b9l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=507&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A microscopic image of a human hookworm.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/photomicrograph-of-human-hookworm-rhabditiform-larva-which-news-photo/901588546?adppopup=true">Smith Collection/Gado/Getty Images</a></span>
</figcaption>
</figure>
<p>Among those adults, 73% displayed elevated intestinal inflammation, while <a href="https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajpa.24731">45% were infected with <em>H. pylori</em></a>, the bacteria that can cause ulcers and cancer.</p>
<p>Taken together, those results demonstrate widespread intestinal infections and inflammation at all ages in these low-income, mostly Black communities.</p>
<p>Long-lasting intestinal infections and associated inflammation can lead to <a href="https://www.sciencedirect.com/science/article/pii/S1471492222001039?casa_token=ImtCTZITFSwAAAAA:-gj-rZCiTwTqo6Fo-ERqHgzdjII7JMnYkD0nw1OLTqvsoqXKVQ6tR9AA6AxZF0l9gDR8OjKyO2I">nutritional deficiencies, restricted growth</a>, <a href="https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0004566">reduced educational attainment, decreased work productivity</a> and increased risk for serious diseases later in life, including <a href="https://link.springer.com/article/10.1007/s10552-020-01295-z">certain cancers</a>). </p>
<h2>A legal challenge in Alabama</h2>
<p>The Rural Embodiment and Community Health Study is not alone in <a href="https://www.medrxiv.org/content/10.1101/2023.01.10.23284404v1">recognizing the impact of intestinal infections</a> on Black communities. One of the <a href="https://www.theguardian.com/us-news/2017/sep/05/hookworm-lowndes-county-alabama-water-waste-treatment-poverty">most widely publicized recent research studies investigating intestinal infections</a> focused on the health effects of poverty and crumbling sanitation infrastructure in Lowndes County, Alabama, a region characterized by a history of racial segregation and inequity. </p>
<p>Researchers found that <a href="https://www.ajtmh.org/view/journals/tpmd/97/5/article-p1623.xml?utm_campaign=buffer&utm_content=buffer20d45&utm_medium=social&utm_source=twitter.com&tab_body=pdf">more than 1 in 3 people tested in Lowndes County were infected with hookworm</a>, an intestinal worm spread through sewage exposure that lives in soil and infects people by burrowing into bare feet.</p>
<p>This 2017 study has since led to legal action.</p>
<p>In a landmark May 2023 court ruling, the Biden administration found that Alabama’s public health department <a href="https://www.reuters.com/legal/us-settles-landmark-alabama-environmental-justice-case-2023-05-04/">had discriminated against Black residents</a> by denying access to adequate sanitation systems and imposed fines for resulting sewage issues.</p>
<figure class="align-center ">
<img alt="An elderly white man is holding hands and walking with a black woman." src="https://images.theconversation.com/files/526819/original/file-20230517-29-sqim7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/526819/original/file-20230517-29-sqim7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/526819/original/file-20230517-29-sqim7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/526819/original/file-20230517-29-sqim7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/526819/original/file-20230517-29-sqim7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/526819/original/file-20230517-29-sqim7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/526819/original/file-20230517-29-sqim7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">President Joe Biden and Catherine Coleman Flowers at the White House on April 21, 2023.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/president-joe-biden-and-catherine-coleman-flowers-founder-news-photo/1252052813?adppopup=true">Drew Angerer/Getty Images</a></span>
</figcaption>
</figure>
<p>This decision is being hailed by environmental justice advocates as a <a href="https://www.theguardian.com/us-news/2023/may/05/alabama-raw-sewage-sanitation-civil-rights-biden">transformative environmental justice agreement</a> that may increase public awareness of the ongoing health crisis that results from infrastructure neglect and associated pathogen exposure. </p>
<p>Community activists – such as <a href="https://www.catherinecolemanflowers.com/">Catherine Coleman Flowers</a>, founder of the <a href="https://www.creej.org/">Center for Rural Enterprise and Environmental Justice</a> – said they hope the federal government continues to intervene, leading to similar results in other affected communities.</p>
<p>“This country’s neglect of wastewater infrastructure in majority Black communities, both urban and rural, is resulting in a hygienic hell for far too many people, a hell that climate change is only making worse,” Flowers said in <a href="https://www.lowndessignal.com/2023/03/13/lowndes-county-wastewater-under-spotlight-again/">a March 2023 interview</a>. </p>
<h2>Why are there still parasites in the US?</h2>
<p>The story of parasite infection in the U.S. is two-sided. </p>
<p>On one hand, the U.S. has successfully controlled many <a href="https://www.cdc.gov/malaria/about/history/elimination_us.html#:%7E:text=In%201949%2C%20the%20country%20was,participation%20in%20operations%20ceased%20altogether">parasite infections</a>. Malaria is one of them. </p>
<p>In addition, advancements in sanitation infrastructure and household construction mean that many Americans do not generally have to worry about parasite infections. </p>
<p>But this national success is not complete, as demonstrated by the recent findings in low-income Black communities across the country. </p>
<p>Limited awareness of the continued threat posed by neglected intestinal infections has made it more difficult to identify and treat these diseases in the U.S. <a href="https://www.npr.org/sections/goatsandsoda/2021/01/22/959204833/why-it-can-be-harder-to-fight-hookworms-in-alabama-than-in-argentina">than in lower-income nations</a>. </p>
<p>For instance, in many countries the drugs needed to treat hookworm infections cost mere cents, but in the U.S., where drug prices are unregulated by the federal government, these same medications can cost <a href="https://www.npr.org/sections/goatsandsoda/2017/12/11/567753423/why-a-pill-thats-4-cents-in-tanzania-costs-up-to-400-in-the-u-s">hundreds of dollars</a>.</p>
<p>The recent court decision in Alabama represents an important step toward increased national recognition of the role intestinal infections play in perpetuating racial health inequities. </p>
<p>Increased awareness will ideally result in improved access to testing and treatment in affected communities. But more work is needed to assess the full extent of these infections across the U.S.</p>
<p>Even if medical treatment is accessible and affordable, vulnerable individuals are often reinfected, as these pathogens continue to spread through the environment. Structural changes are needed to break the cycle of infection and poor health.</p>
<p><a href="https://www.whitehouse.gov/briefing-room/statements-releases/2021/11/06/fact-sheet-the-bipartisan-infrastructure-deal/">Current federal investment</a> in community infrastructure – including water quality – is encouraging but does not go far enough. Ultimately, a concentrated nationwide effort to update and maintain sanitation systems is the best way to finally halt infection transmission and support health equity across the U.S.</p><img src="https://counter.theconversation.com/content/205616/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Theresa E. Gildner does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Though many Americans believe that parasitic infections exist in poorer countries, research shows that the problem exists in the US and has a higher impact in communities of color.Theresa E. Gildner, Assistant Professor of Biological Anthropology, Arts & Sciences at Washington University in St. LouisLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2039592023-04-18T15:38:49Z2023-04-18T15:38:49ZHow to be sushi smart: tips on avoiding anisakis disease<figure><img src="https://images.theconversation.com/files/521270/original/file-20230417-16-akyh66.jpg?ixlib=rb-1.1.0&rect=0%2C25%2C1756%2C1014&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Nematode larvae belonging to the genus _Anisakis_ can cause the disease anisakiasis, a threat to human health.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/es/image-photo/living-anisakis-worm-just-found-on-1142197133">Shutterstock / WH_Pics</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>From sushi and sashimi (Japan) to poke bowls (Hawaii) and ceviche (Peru), consumption of raw or undercooked fish and other seafood is becoming increasingly popular. Appealing as such dishes can be, they can also increase the risk of exposure to fish-borne parasites. </p>
<p>It’s not a matter to take lightly. Every year, almost one in ten people fall ill from eating contaminated food. The World Health Organisation estimates that some <a href="https://www.sciencedirect.com/science/article/pii/S0020751905002766">56 million cases</a> of parasitic infections associated with the consumption of fish products occur annually.</p>
<h2>Tiny but troublesome stowaways</h2>
<p>Among the fish-borne parasites that can affect humans, there are three major groups of parasitic worms, also known as <em>helminths</em>: flatworms, spiny-headed worms (acanthocephalans) and ciliated worms (nematodes).</p>
<p>Diagnoses of infection with Opisthorchis, a family of flatworms, are the most common, but they occur mainly in <a href="https://pubmed.ncbi.nlm.nih.gov/33158552/">East and Southeast Asia</a>. Of more global concern are those caused by some nematodes of the family Anisakidae, particularly species of the genera <em>Anisakis</em>, <em>Pseudoterranova</em> and <em>Contracaecum</em>. As a consequence, they’re the focus of much of the world’s medical and economic concern.</p>
<p>The parasitic disease <a href="https://www.cdc.gov/parasites/anisakiasis/index.html">anisakiasis</a>, caused by nematode larvae belonging to the genus <em>Anisakis</em>, is considered the main threat to human health. Every year and on all continents, countless cases are diagnosed in humans, in part because the rise in consumption of foods such as sushi and sashimi. In Japan alone, where it is traditional to eat raw fish and seafood dishes, more than <a href="https://pubmed.ncbi.nlm.nih.gov/33025215/">7,000 cases of anisakiasis occur annually</a>.</p>
<h2>From marine mammals to human stomachs</h2>
<p>Today, anisakiasis is not only an emerging global human health problem, but it is also an economic concern, due to the potential negative effects on consumer confidence and trade associated with infected fish products.</p>
<p>So how can this troublesome disease be avoided? The answer lies in understanding the parasites’ life cycle.</p>
<p>The genus <em>Anisakis</em> comprises nine species, three of which (<em>Anisakis simplex</em>, <em>Anisakis pegreffii</em> and <em>Anisakis physeteris</em>) have been confirmed as zoonotic pathogens. These nematodes infect a wide range of marine organisms; fish and cephalopods serve as intermediate hosts, while dolphins, whales, seals and other marine mammals are the <a href="https://www.nature.com/articles/s41598-022-17710-1">final hosts</a>.</p>
<p>Adult worms are found in the mucous membrane that lines the stomachs of marine mammals. The parasite’s eggs are expelled along with the animal’s faeces and hatch in seawater. There, krill – small crustaceans that form the basis of the ocean food chain – eat them and become infected with larval stages of the nematodes. When the krill are in turn eaten by fish or squid, another stage of larvae infects the predators’ guts and become embedded on the surface of their organs and eventually in their muscles.</p>
<p>And that’s where we humans come in. When we consume fish, squid, octopus or other seafood containing <a href="https://www.cdc.gov/parasites/anisakiasis/biology.html">third-stage <em>Anisakis</em> larvae</a> that’s raw or undercooked, we can become accidental hosts to <em>Anisakis</em> larvae. Once ingested, they settle in our stomach and sometimes the small intestine.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/518175/original/file-20230329-14-yedtuz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/518175/original/file-20230329-14-yedtuz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/518175/original/file-20230329-14-yedtuz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/518175/original/file-20230329-14-yedtuz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/518175/original/file-20230329-14-yedtuz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/518175/original/file-20230329-14-yedtuz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/518175/original/file-20230329-14-yedtuz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/518175/original/file-20230329-14-yedtuz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/es/image-photo/parasites-under-microscope-woman-suffering-helminthiasis-2223896623">New Africa/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Stomach pain and worse</h2>
<p>While the parasite cannot reproduce in humans, it can survive for a short period of time and cause anisakiasis, which can range from mild to severe depending on the person infected. The most typical symptoms of gastric anisakiasis include abdominal pain, nausea and vomiting within hours of ingesting the larvae. Other symptoms can include <a href="https://pubmed.ncbi.nlm.nih.gov/25039016/">allergic reactions</a> and even <a href="https://www.mayoclinic.org/diseases-conditions/anaphylaxis/symptoms-causes/syc-20351468">anaphylactic shock</a>. Infection of the small intestine is less common, but when it occurs it can result in an inflammatory mass and symptoms similar to <a href="https://www.niddk.nih.gov/health-information/digestive-diseases/crohns-disease">Crohn’s disease</a>, which develops one to two weeks later.</p>
<p>Some workers in the fishing industry as well as cooks and other professionals who regularly deal with fish may suffer from occupational allergic anisakiasis. Here, ingestion of the parasite’s larvae is not necessary for the disease to occur – those affected become <a href="https://pubmed.ncbi.nlm.nih.gov/28429304/">sensitive to <em>Anisakis</em> proteins</a> that come into contact with the skin or respiratory tract.</p>
<p>Thankfully, the overall prognosis for anisakiasis is generally positive. Most infections are self-limiting and usually resolve spontaneously after several weeks. Person-to-person transmission is effectively impossible.</p>
<h2>Ceviche, sashimi and even pickled anchovies</h2>
<p>More than 90% of anisakiasis cases worldwide are reported in Japan, and most of the remaining 10% in countries such as Spain, Italy, the United States (Hawaii), the Netherlands and Germany. These are regions where we traditionally eat raw or undercooked fish dishes such as sushi and sashimi, ceviche and carpaccio, <a href="https://www.sciencedirect.com/science/article/pii/S0034528823000607">pickled or pickled anchovies</a>, Hawaiian-style <a href="https://en.wikipedia.org/wiki/Lomi-lomi_salmon">salmon lomi-lomi</a> and salted herring. The species that are <a href="https://www.sciencedirect.com/science/article/pii/S0078323422000446">most frequently parasitised</a> include salmon, tuna, squid, cod, hake, mackerel, mackerel, horse mackerel, blue whiting, sardines and anchovies.</p>
<p>How can anisakiasis be prevented? Preventive measures are essential to control and minimise the disease. While the worms can resist pickling and smoking, semi-preserves such as anchovies and traditionally salted dried fish such as cod or mojamas involve processes that kill the parasite. The best approach is to use a traditional cooking technique such as cooking, frying, baking or grilling. The <a href="https://www.aesan.gob.es/AECOSAN/web/seguridad_alimentaria/subdetalle/anisakis.htm">Spanish Agency for Food Safety and Nutrition</a> reports that when the cooking temperature of a seafood reaches or exceeds 60°C (140 Fahrenheit) for at least one minute, the parasite is killed.</p>
<p>While such methods aren’t an option for fans of sushi, sashimi, and ceviche, freezing is. When seafood is subjected to -20°C for seven days or -35°C for more than 15 hours, the <a href="https://pubmed.ncbi.nlm.nih.gov/32247867/">larvae are destroyed</a>. If you’re not sure that your freezer can go that low, it’s prudent to buy frozen fish. Indeed, to increase consumer food safety, in some countries, commercially prepared sushi is frozen before being sold.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/521606/original/file-20230418-24-ei0c1n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/521606/original/file-20230418-24-ei0c1n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/521606/original/file-20230418-24-ei0c1n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=150&fit=crop&dpr=1 600w, https://images.theconversation.com/files/521606/original/file-20230418-24-ei0c1n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=150&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/521606/original/file-20230418-24-ei0c1n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=150&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/521606/original/file-20230418-24-ei0c1n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=189&fit=crop&dpr=1 754w, https://images.theconversation.com/files/521606/original/file-20230418-24-ei0c1n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=189&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/521606/original/file-20230418-24-ei0c1n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=189&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Left: A coiled anisakid worm (<em>Pseudoterranova decipiens</em>) in a fillet of cod. Center: The head end of <em>Pseudoterranova decipiens</em>. Right: A <em>Pseudoterranova decipiens</em> recovered from a human patient.</span>
<span class="attribution"><a class="source" href="https://www.cdc.gov/parasites/anisakiasis/index.html">DPDx/CDC</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p><a href="https://food.ec.europa.eu/system/files/2016-10/biosafety_fh_eu_food_establishments-20111214_scfcah_guidance_parasites_en.pdf">European legislation</a> requires that seafood not be offered for sale with visible parasites. To avoid anisakiasis, it’s advisable to buy clean and gutted fish and to visually inspect them – even fish fillets merit examination. </p>
<p>There are a few exceptions from the freezing requirement. Oysters, mussels, clams, and other molluscs; fish from inland waters (rivers, lakes, marshes…) and freshwater fish farms (trout and carp, for example). Farm-raised fish may also be safe, providing that they were reared from embryos obtained in captivity, fed with feed without zoonotic parasites, and kept in a parasite-free environment.</p>
<p>While there’s much to be aware of, it’s better than suffering the consequences of inattention or inaction. With the correct steps and a measure of precaution, it’s possible to enjoy seafood in a safe and responsible way.</p><img src="https://counter.theconversation.com/content/203959/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Raúl Rivas González ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'a déclaré aucune autre affiliation que son organisme de recherche.</span></em></p>Raw seafood dishes such as sushi, poke bowls and ceviche are increasingly popular, but can harbour fish-borne parasites. What’s the best way to protect ourselves?Raúl Rivas González, Miembro de la Sociedad Española de Microbiología. Catedrático de Microbiología, Universidad de SalamancaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1991562023-02-02T22:18:37Z2023-02-02T22:18:37ZGuinea worm: A nasty parasite is nearly eradicated, but the push for zero cases will require patience<figure><img src="https://images.theconversation.com/files/507952/original/file-20230202-14714-ndbz5k.jpg?ixlib=rb-1.1.0&rect=3%2C3%2C510%2C334&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Guinea worms are long, white parasites that emerge from the legs of infected people through painful blisters.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Dracunculus_medinensis.jpg#/media/File:Dracunculus_medinensis.jpg">CDC/Wikimedia Commons</a></span></figcaption></figure><p>A painful, parasitic disease that once infected 3.5 million people per year is tantalizingly close to being eradicated.</p>
<p>On Jan. 24, 2023, <a href="https://www.cartercenter.org">The Carter Center</a>, a nonprofit founded by former U.S. President Jimmy Carter, announced that “Guinea worm is poised to become the second human disease in history <a href="https://www.cartercenter.org/news/pr/2023/2022-guinea-worm-worldwide-cases-announcement.html">to be eradicated</a>,” having recorded just 12 cases worldwide in 2022. It represents the lowest annual figure since 1986, when the <a href="https://www.cartercenter.org">Carter Center</a> began leading global efforts to eradicate Guinea worm disease. </p>
<p>I have been <a href="https://scholar.google.com/citations?user=yb246-8AAAAJ&hl=en&oi=ao">working as a parasitologist</a> for over two decades. I know the suffering that parasitic diseases like Guinea worm infections inflict on humanity, especially on the world’s most vulnerable and poor communities. <a href="https://www.clemson.edu/science/academics/departments/genbio/about/profiles/kpaul">My own research</a> on African sleeping sickness – a deadly disease caused by a parasite carried by tsetse flies – has shown me how difficult it is to fight these diseases.</p>
<p>Thanks to a massive global effort, Guinea worm is now almost gone. However, humanity has been <a href="https://www.who.int/teams/control-of-neglected-tropical-diseases/dracunculiasis/dracunculiasis-eradication-portal">tantalizingly close to fully eradicating Guinea worm</a> for many years. To take the final step from almost gone to fully eradicated is not easy, but with patience and vigilance, it is possible.</p>
<h2>A painful and persistent parasite</h2>
<p>Guinea worms are parasitic nematodes that infect humans and a few other animals. They live in ponds, rivers and creeks all across Africa but are mostly endemic to sub-Saharan Africa. </p>
<p>A Guinea worm infection is a nasty experience. The worm mainly infects people after they drink water that is contaminated with tiny crustaceans called <a href="https://www.cdc.gov/parasites/guineaworm/biology.html">copepods that are infected with worm larvae</a>. Most people don’t realize they are infected for about a year – roughly the time it takes for the larvae to burrow their way out of the stomach and into the abdominal cavity, develop into adults and mate. Once the females mature into pregnant worms, the horror show begins. </p>
<p>The pregnant worms must get back to the water to give birth, so they crawl down to the lower leg or foot. Once there, they <a href="https://www.cartercenter.org/news/multimedia/slideshows/guinea-worm-photo-downloads.html">burrow out through an incredibly painful blister</a> in a process that can take weeks. The intense pain causes people to plunge their leg into water to get relief, and this is when the worm expels her larvae, starting the cycle anew. </p>
<p>There are no vaccines or drugs for Guinea worm. The current best treatment is very low-tech: treat the wound and <a href="https://www.cdc.gov/parasites/guineaworm/treatment.html">slowly extract the worm over several painful weeks</a>. Due to the intense pain, infected adults cannot work or provide for their families. Infected kids miss school and fall behind on their education. Though there are usually no long-term complications, infection confers no immunity, so people can get infected repeatedly over their lifetimes, too.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/507953/original/file-20230202-14479-wj9b1v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Three children with black filtration straws." src="https://images.theconversation.com/files/507953/original/file-20230202-14479-wj9b1v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/507953/original/file-20230202-14479-wj9b1v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/507953/original/file-20230202-14479-wj9b1v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/507953/original/file-20230202-14479-wj9b1v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/507953/original/file-20230202-14479-wj9b1v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/507953/original/file-20230202-14479-wj9b1v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/507953/original/file-20230202-14479-wj9b1v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Tools like filtration straws, the black tubes being held by these children in the north-central African country of Chad, can prevent Guinea worm infection.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Preventing_Guinea_worm_disease_in_Chad_(34173755220).jpg#/media/File:Preventing_Guinea_worm_disease_in_Chad_(34173755220).jpg">CDC Global/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Path to eradication</h2>
<p>Guinea worm is awful, so I welcome any news of removing it from the list of diseases that affect people. But alongside hope, a healthy dose of realism is needed: Eradicating any disease is difficult. So far, humanity has succeeded only with smallpox, which was <a href="https://www.who.int/news-room/feature-stories/detail/the-smallpox-eradication-programme---sep-(1966-1980)">eradicated with the help of vaccines in the late 1970s</a> after 200 years of effort.</p>
<p>A disease like Guinea worm is a distinctly different challenge. Eradication will not come from a medical solution like a pill or vaccine. Instead, people will have to change their behavior. The ideas are simple, but that does not mean this will be easy.</p>
<p>The Guinea worm eradication program has employed a two-part strategy to <a href="https://www.cartercenter.org/health/guinea_worm/index.html">interrupt the Guinea worm’s transmission cycle</a>. The first part was to prevent people from getting infected from contaminated water and food. The program launched educational campaigns, ran surveillance programs and distributed millions of tools – like filtration cloths, filters and chemical water treatments – for people to secure clean water.</p>
<p>The second part of the plan was aimed at preventing reintroduction of the parasite into the environment. Again, education programs were a key component, but so were Guinea worm treatment centers. These centers acted as places where infected people and their families could receive care, food and shelter during the long treatment process. By giving infected people a place to stay, treatment centers prevent a person from putting their leg into a body of water and inevitably releasing the larva.</p>
<p><iframe id="pyuwi" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/pyuwi/6/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<h2>A difficult last step</h2>
<p>Since the eradication effort began in the mid-1980s, annual Guinea worm infections have fallen from the millions down to the dozens. But the final push to zero has been difficult and slow. In 2015, there were <a href="https://www.cartercenter.org/news/pr/guinea-worm-worldwide-cases-Jan2016.html">just 22 recorded cases</a>, but infections have stayed in the low double-digits since then.</p>
<p>The massive drop in Guinea worm cases showed that this strategy was working, but there was a complication. In 2020, researchers discovered that a Guinea worm outbreak in the Central African country of Chad was <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7255611/">driven by infected dogs</a>, adding a new set of challenges to interrupting the transmission cycle. This led to public health officials returning to the field, increasing surveillance and urging people to <a href="https://doi.org/10.4269/ajtmh.20-1525">report and contain infected dogs</a>.</p>
<p>These many eradication efforts since 2015 have slowly brought case numbers down to the current record low of 12 total cases.</p>
<p>As the world approaches zero cases of Guinea worm disease, the laborious epidemiological detective work of chasing down infection reports and finding hidden water sources gets tougher. Some of the few remaining communities affected by Guinea worm are nomadic or very remote. And as Guinea worm infections grow rare, vigilance can wane and people revert to their old ways, opening the door for Guinea worm to reemerge.</p>
<p>The final push to full eradication will be a challenge that requires patience and faith on the part of institutions and governments supporting the effort. But it also requires that millions of people living in endemic areas do what they can to break the transmission cycle and kick Guinea worm out for good.</p><img src="https://counter.theconversation.com/content/199156/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kimberly Paul receives funding from the National Institutes of Health. </span></em></p>After nearly 40 years of effort, Guinea worm disease is on the cusp of being the second human disease – after smallpox – to be eradicated on Earth.Kimberly Paul, Associate Professor of Biochemistry, Clemson UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1971002023-01-04T16:46:53Z2023-01-04T16:46:53ZToxoplasma: the parasite that takes over our brains<figure><img src="https://images.theconversation.com/files/502752/original/file-20221230-12-q85u5j.png?ixlib=rb-1.1.0&rect=11%2C11%2C2456%2C1653&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Toxoplasma gondii cyst hosted in a mouse’s brain.</span> <span class="attribution"><a class="source" href="https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1002201">Jitender P. Dubey / PLOS Biology</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>A recurring fantasy in science fiction is the implantation of tiny elements in peoples’ brains, which would be used to control and direct our actions and emotions. Regardless of the direction that technological development may take in this sense, in nature these tricks were invented millions of years ago. Different types of parasites are able to <a href="https://brill.com/view/journals/beh/155/7-9/article-p671_5.xml">modify the behaviour</a> of organisms that host them, forcing them to stop acting to conserve their own genes to become promoters of foreign ones.</p>
<p><a href="https://www.cell.com/current-biology/pdf/S0960-9822(18)30671-7.pdf"><em>Toxoplasma gondii</em></a> is one of the most common parasites in humans. It is hosted by approximately one third of people. Even so, most of us only know of its existence during pregnancy, when pregnant women receive instructions to not eat uncooked meat because it might cause <em>toxoplasma gondii</em>. Nevertheless, all signs point to the fact that it plays an important role in many aspects of our lives.</p>
<p>Toxoplasma is a protozoan, a unicellular being so small that it lives inside animal cells. This parasite only reproduces sexually in the intestine of felines (the definitive hosts) but it has a complex life cycle and spends periods of time being hosted by other animals – from birds to crocodiles and from rodents to cetaceans. The list of possible hosts also includes humans.</p>
<p>Intermediate hosts acquire toxoplasma by ingesting its oocysts (which are a bit like its eggs) via surfaces or food contaminated with feline excrement, or by ingesting other intermediate hosts that are already infected.</p>
<p>When toxoplasma enters the body of intermediate hosts, it acts in a very surprising way. It begins to reproduce asexually and takes control of our immune system, promoting a specific response that causes the parasite to form cysts in different tissues, with a preference for <a href="https://www.frontiersin.org/articles/10.3389/fimmu.2019.00242/full">the brain</a>.</p>
<p>When the immune response is deficient, as occurs with foetuses or immunosuppressed individuals (for example, people with HIV), the toxoplasma does not encyst and proliferates in the intermediate host, thereby causing severe disease. When the immune response does act, the process of infection and cyst formation is asymptomatic or generates only mild discomfort.</p>
<p>These cysts are essentially waiting for a feline to come along and eat the intermediate host – which would give rise to a new population of toxoplasma. But the wait is far from passive. The toxoplasma does everything it can to make this predation event happen. <a href="https://www.annualreviews.org/doi/abs/10.1146/annurev-animal-081720-111125">And it can do a lot</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/433988/original/file-20211125-21-1kapnml.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/433988/original/file-20211125-21-1kapnml.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=403&fit=crop&dpr=1 600w, https://images.theconversation.com/files/433988/original/file-20211125-21-1kapnml.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=403&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/433988/original/file-20211125-21-1kapnml.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=403&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/433988/original/file-20211125-21-1kapnml.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=506&fit=crop&dpr=1 754w, https://images.theconversation.com/files/433988/original/file-20211125-21-1kapnml.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=506&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/433988/original/file-20211125-21-1kapnml.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=506&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Toxoplasma gondii cyst hosted in a mouse’s brain, similar to the parasites that one third of human beings have. The reddish elements that can be seen in the cyst are bradyzoites, dormant individuals that would give rise to a new infection if the mouse were eaten by a cat.</span>
<span class="attribution"><span class="source">Jitender P. Dubey/Wikimedia Commons</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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</figure>
<h2>Kamikaze mice</h2>
<p>As a general rule, without toxoplasma, rodents try to minimise the chance of being eaten by predators. To do this, they travel via sheltered places and move away when they come across any evidence of the presence of cats.</p>
<p><a href="https://link.springer.com/article/10.1186/s13071-020-04528-x">When a rodent hosts toxoplasma cysts</a>, however, it begins to exhibit reckless behaviour, exposing itself in open areas and going to places marked with the scent of cat faeces and urine. Equally uninhibited behaviours occur in other animals hosting toxoplasma cysts. <a href="https://www.nature.com/articles/s41467-021-24092-x">Hyenas</a> get closer to lions,
<a href="https://www.sciencedirect.com/science/article/pii/S2213224413000035">Tasmanian marsupials</a> start being careless and are more frequently run over on roads and <a href="https://www.sciencedirect.com/science/article/pii/S0020751905002444#bib77">sea otters</a> (infected by contamination of the water with cat faeces) fall prey to sharks more easily.</p>
<p>The abandoning of prudent behaviour implies a radical change in one of the main premises of animal life – the drive for self-preservation. A tiny parasite starts making the decisions rather than the animal. </p>
<p>So, could it also be possible that toxoplasma influences human behaviour?</p>
<p>Until recently, the presence of toxoplasma cysts in humans was considered to be asymptomatic. But there is an increasing amount of solid evidence <a href="https://www.sciencedirect.com/science/article/pii/S147149222030221X">to the contrary</a>. It has been proven that the presence of toxoplasma cysts among people who die in traffic accidents is disproportionately high, and it is thought that the parasite would be responsible for several million of these accidents each year.</p>
<p>Accidents are not necessarily the result of fearless behaviour, but <a href="https://link.springer.com/article/10.1007/s10096-018-3427-z">a recent study</a> of around 100 deaths linked reckless deaths to toxoplasma infection, as occurs in rats, mice, hyenas or sea otters. It is also known that around <a href="https://www.sciencedirect.com/science/article/pii/S147149222030221X">20% of cases of schizophrenia</a> are related to the presence of toxoplasma cysts, and there are indications that they are involved in other psychological disorders.</p>
<p>Likewise there is a strong association between toxoplasma and suicide attempts, to the point that it is estimated that every year more than one million suicide attempts worldwide are related to the parasite.</p>
<p>Until now, toxoplasma in a dormant state presents itself as a serious public health problem, which poses enormous challenges to health systems and which, until very recently, had been overlooked. But there’s more.</p>
<h2>Entrepreneur cysts</h2>
<p>Toxoplasma generates behavioural changes with potential importance in human societies. For example, there seems to be a relationship between carrying toxoplasma cysts and starting a business. People carrying the parasite are more likely to want to be entrepreneurs when they are students and to start their own businesses in adult life.</p>
<p>In a <a href="https://journals.sagepub.com/doi/abs/10.1177/1042258719890992">study</a> involving more than 16,000 Danish women, it was found that those living with toxoplasma were more entrepreneurial, a particularly notable difference when it came to solo entrepreneurship, but they also abandoned their business venture more easily. These observations may be related to those of another <a href="https://www.nature.com/articles/s41598-017-10926-6">study</a> in which it was observed that hosting toxoplasma causes people to place less importance on the benefits they can obtain from their actions, which would make them take more risks, dismissing the consequences.</p>
<p>All these changes seem to reflect a decrease in neophobia associated with toxoplasma, which would make us face new situations without fearing the risks they imply. This reduced fear of the unknown is characteristic of <a href="https://royalsocietypublishing.org/doi/full/10.1098/rstb.2020.0049">individuals responsible for new inventions</a>, who are the ones who create cultural innovations. </p>
<p>Along the same lines, it is possible to speculate about the role of toxoplasma in great changes in human societies. I like to imagine that the first person who painted animals or represented the palms of their hands on a cave had toxoplasma cysts in their brain, just like the person who dared to control fire or create musical instruments. Perhaps those who embarked on intrepid voyages of exploration, those who tried drugs for the first time, those who began breeding the wolves that eventually gave rise to the dog, or those who grew the teosinte that finally produced corn, had toxoplasma. Perhaps Bach, Frida Kahlo, Jimmy Hendrix or Marie Curie achieved their achievements with the help of a small parasite hosted in their brains, waiting for a feline to eat them.</p>
<h2>A parasite against free will</h2>
<p>We humans like to see ourselves as the pinnacle of evolution. But toxoplasma is here to take us down a notch. What we consider to be our free will may, in some cases, actually be the intentions of a tiny being that has slipped into our brains.</p>
<p>It could even be the case that this parasite has participated in humanity’s great innovations and feats.</p><img src="https://counter.theconversation.com/content/197100/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Miguel Clavero Pineda no recibe salario, ni ejerce labores de consultoría, ni posee acciones, ni recibe financiación de ninguna compañía u organización que pueda obtener beneficio de este artículo, y ha declarado carecer de vínculos relevantes más allá del cargo académico citado.</span></em></p>Toxoplasma is a protozoan, a single-celled organism so small that it lodges inside the cells of animals (one in three humans) and modifies their behaviour.Miguel Clavero Pineda, Científico titular CSIC, Estación Biológica de Doñana (EBD-CSIC)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1932332022-10-30T10:52:33Z2022-10-30T10:52:33ZVaccines could be a game-changer in the fight against malaria in Africa<figure><img src="https://images.theconversation.com/files/491862/original/file-20221026-13-1efpnj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The first malaria vaccine, Mosquirix, was approved by the WHO in 2021.</span> <span class="attribution"><span class="source">Brian Ongoro/AFP via Getty Images</span></span></figcaption></figure><p>The development of an effective vaccine for malaria has proved to be far more challenging than developing a vaccine to protect people from COVID-19. Several different COVID-19 vaccines were <a href="https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/overview-COVID-19-vaccines.html">developed and approved</a> for use within a year of the disease’s emergence. </p>
<p>In contrast, it took over 30 years of intensive research and numerous clinical trials by the Walter Reed Army Institute of Research and partners before the <a href="https://www.who.int/news/item/06-10-2021-who-recommends-groundbreaking-malaria-vaccine-for-children-at-risk">first malaria vaccine</a>, Mosquirix, was approved for use by the World Health Organization (WHO) in 2021. </p>
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Read more:
<a href="https://theconversation.com/malaria-vaccine-is-a-major-leap-forward-but-innovation-mustnt-stop-here-169639">Malaria vaccine is a major leap forward: but innovation mustn't stop here</a>
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<p>Creating a vaccine for a vector-borne disease such as malaria is very challenging. The parasite takes on <a href="https://www.dw.com/en/oxford-malaria-vaccine-promising-results-in-trials/a-63065352">different forms in different hosts</a>. And it’s constantly evolving to evade the human immune system and control interventions.</p>
<p>In a major step towards the equitable roll-out of Mosquirix, the WHO awarded the vaccine <a href="https://www.gsk.com/en-gb/media/press-releases/who-grants-prequalification-to-gsk-s-mosquirix-the-first-and-only-approved-malaria-vaccine/">prequalification status</a> in September 2022. The prequalification step follows approval. It ensures that only good quality products are procured and distributed by United Nations agencies and other major donors. </p>
<p>Most recently, researchers from Burkina Faso and Oxford University’s Jenner Institute – the same institution that developed the Oxford/AstraZeneca COVID-19 vaccine – made their own revelation. They <a href="https://www.bbc.com/news/health-62797776">released</a> very encouraging data from a clinical trial assessing the novel R21 malaria vaccine. </p>
<p>Like Mosquirix, the R21 vaccine targets the sporozoite. This is the malaria parasite stage that is transferred to humans when the malaria-infected female Anopheles mosquito is taking a blood meal. When effective, both vaccines ensure that the sporozoites are destroyed before they enter the liver. It effectively prevents malaria infection by halting the parasite life cycle in the human host.</p>
<p>The fight against malaria has been significantly strengthened with the addition of malaria vaccines to the suite of prevention measures. These vaccines have the potential to reduce malaria-related illness and and death in children under the age of five – one of the populations currently <a href="https://www.who.int/news-room/fact-sheets/detail/malaria">most affected by malaria</a>. </p>
<h2>What studies show</h2>
<p>Both vaccines – Mosquirix and R21 – target the same parasite stage and use the same malaria proteins. But Oxford’s R21 vaccine contains a higher number of these malaria proteins. And it uses a different adjuvant – a chemical substance that stimulates the body’s immune response. These two factors are thought to improve the efficacy of the R21 vaccine by causing a stronger immune response. </p>
<p>The preliminary data are drawn from a <a href="https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(22)00442-X/fulltext">two-year study</a> involving 409 children aged five to 17 months. The children received a booster dose 12 months after receiving the first three doses of the vaccine. The data suggest that the R21 vaccine resulted in a <a href="https://www.sabcnews.com/sabcnews/oxford-malaria-vaccine-data-bodes-well-for-effort-to-combat-deadly-disease/">higher level of protection</a> than Mosquirix. </p>
<p>Eight out of every 10 children who received four doses of the R21 vaccine did not develop malaria over the trial period – making this malaria vaccine the <a href="https://www.ox.ac.uk/news/2022-09-08-malaria-booster-vaccine-continues-meet-who-specified-75-efficacy-goal">first to meet the WHO minimum efficacy target</a> of 75% for 12 months in the target population of young African children.</p>
<p>These study results are encouraging. </p>
<p>But researchers have cautioned against a direct comparison between the performance of the R21 and Mosquirix vaccines. Unlike the Mosquirix vaccine, the R21 vaccine was given to children before the start of the malaria season. And it was only <a href="https://www.medicalnewstoday.com/articles/malaria-new-vaccine-candidate-shows-promise-in-clinical-trials#Plans-for-a-phase-3-trial">tested</a> on a small number of children from one region in Burkina Faso. In addition, a number of control and prevention measures were in place. </p>
<p>A larger study is needed to confirm vaccine efficacy in African children across the continent. This study must be done in regions with differing malaria transmission intensities, differing levels of malnutrition and anaemia in the target populations, and varying coverage of control interventions. </p>
<p>Four thousand eight hundred children from four African countries – two of which have malaria transmission all year round – have been enrolled in a <a href="https://www.nature.com/articles/d41586-022-02902-6">phase 3 clinical trial</a>. The aim of this trial is to demonstrate vaccine safety and efficacy in a larger, more diverse group of children. The researchers from the Jenner Institute expect the R21 vaccine to be approved for use next year, as long as no unexpected safety concerns are raised in this larger trial.</p>
<p>Manufacturing and distribution bottlenecks <a href="https://blogs.worldbank.org/health/new-data-illuminates-acute-vaccine-supply-delivery-gaps-developing-countries">prevented</a> the timely and equitable distribution of COVID-19 vaccines. To avoid a repeat, the University of Oxford has signed a manufacturing agreement with the Serum Institute of India, the largest manufacturer of vaccines globally. Under this agreement, the Serum Institute has agreed to supply at least 200 million doses annually. This is significantly more than the 15 million to 18 million doses of Mosquirix that GlaxoSmithKline is contracted to produce every year <a href="https://www.reuters.com/business/healthcare-pharmaceuticals/oxford-malaria-vaccine-data-bodes-well-effort-combat-deadly-disease-2022-09-07/">until 2028</a>.</p>
<p>But, according to <a href="https://www.reuters.com/business/healthcare-pharmaceuticals/why-worlds-first-malaria-shot-wont-reach-millions-children-who-need-it-2022-07-13/">the WHO</a>, this quantity is far lower than the projected demand for vaccines. To increase manufacturing capacity, the Jenner Institute is in talks with African vaccine manufacturers.</p>
<h2>Moving forward</h2>
<p>Getting the vaccines manufactured is only the first step. </p>
<p>Other hurdles include ensuring that countries can procure the vaccines, that there is equitable delivery of the vaccines to the requesting countries, and that there is prompt vaccines distribution to all healthcare facilities within the malaria risk areas. And most importantly, that there is optimal uptake of the vaccines.</p>
<p>Misinformation, <a href="https://www.phillyvoice.com/covid-19-vaccine-hesitancy-parents-children/">vaccine hesitancy</a> and safety concerns have contributed to a lower rate of vaccination against COVID-19, particularly among children. </p>
<p>For a malaria vaccine to have an impact, health promotion is key. Awareness campaigns must address safety concerns, while emphasising expected positive impacts of the vaccine. These campaigns must target both healthcare professionals and affected communities. They must be delivered before and during vaccine roll-out to ensure any new misinformation or concerns are promptly and effectively addressed.</p><img src="https://counter.theconversation.com/content/193233/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jaishree Raman is affiliated with the National Institute for Communicable Diseases, the Wits Research Institute for Malaria and University of Pretoria's Institute for Sustainable Malaria Control and receives funding from the South African Research Trust, the Gates Foundation, the Global Fund, the Clinton Health Access Initiative, the South African Medical Research Council, and the National Institute for Communicable Diseases.</span></em></p>For a malaria vaccine to have an impact, health promotion is key. Awareness campaigns must address safety concerns and emphasise expected positive impacts.Jaishree Raman, Principal Medical Scientist and Head of Laboratory for Antimalarial Resistance Monitoring and Malaria Operational Research, National Institute for Communicable DiseasesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1785772022-10-27T09:14:59Z2022-10-27T09:14:59ZThe unusual ways viruses and parasites use their cell membranes to spread – and how scientists are fighting back<figure><img src="https://images.theconversation.com/files/491703/original/file-20221025-3834-llifm3.jpg?ixlib=rb-1.1.0&rect=4%2C0%2C994%2C693&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Red onion skin cells seen through a microscope.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/high-resolution-light-photomicrograph-onion-epidermus-233534170">Claudio Divizia/Shutterstock</a></span></figcaption></figure><p>Cell membranes make up the exterior of all cells and are a basic structure found in most living organisms. But they can also help parasites survive in the human body, play an important part in cancer growth and enclose and protect deadly viruses, including the one that causes COVID. Scientists are looking to understand how bilayers (cell membranes with two layers) work and whether they can be used to develop new drugs to combat infections.</p>
<p>It has been known for a long time that living cells are enclosed <a href="https://academic.oup.com/aob/article-abstract/32/3/457/444888?redirectedFrom=fulltext">by a fatty layer</a> that separates different cells. This can be clearly seen in red onion skin cells in which the dye that gives the onion its distinctive colour is confined in these layers. Building on previous work, Seymour Singer and Garth Nicolson suggested a structure for this layer in 1972 which they called <a href="https://www.sciencedirect.com/science/article/pii/S0005273613003933?ia=ihub">the fluid mosaic model</a>. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/491706/original/file-20221025-21-4dgpm7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Red onion cut in half revealing red layers." src="https://images.theconversation.com/files/491706/original/file-20221025-21-4dgpm7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/491706/original/file-20221025-21-4dgpm7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/491706/original/file-20221025-21-4dgpm7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/491706/original/file-20221025-21-4dgpm7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/491706/original/file-20221025-21-4dgpm7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/491706/original/file-20221025-21-4dgpm7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/491706/original/file-20221025-21-4dgpm7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Visible bilayers.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/red-onion-isolated-on-white-background-304270775">Jiang Hongyan/Shutterstock</a></span>
</figcaption>
</figure>
<p>Their model has since been found to explain many features in living organisms. The bilayer is even part of the structure and function of many viruses such as influenza and SARS-Covid-2. Viral particles can use it as a protective layer which helps them to spread. For example, we can trace how a viral particle of SARS-Covid-2 enters a lung cell and what happens next.</p>
<p>When one of these viral particles enters a lung cell, it releases its ribonucleic acid (RNA) – single-stranded genetic code. This translates into viral proteins on ball-like structures called ribosomes that are attached to membranes inside the host cell. These viral proteins are then transported to another part of the cell called <a href="https://www.hopkinsmedicine.org/news/articles/the-weird-way-coronaviruses-assemble-their-offspring">the Golgi apparatus</a> which encloses them in lipid (fatty) bilayers. They then make a further journey, fusing with the surface membrane of the cell, before leaving it altogether – a process known as exocytosis. </p>
<figure class="align-right ">
<img alt="Man coughing into clenched fist." src="https://images.theconversation.com/files/491709/original/file-20221025-15-hham00.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/491709/original/file-20221025-15-hham00.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/491709/original/file-20221025-15-hham00.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/491709/original/file-20221025-15-hham00.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/491709/original/file-20221025-15-hham00.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/491709/original/file-20221025-15-hham00.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/491709/original/file-20221025-15-hham00.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Virus particles go through a number of changes before spreading.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/spread-pathogens-when-coughing-shown-man-1720857718">Ralf Geithe/Shutterstock</a></span>
</figcaption>
</figure>
<p>When the virus leaves the cell it carries <a href="https://doi.org/10.1038/s41579-020-00468-6">some of the membranes</a> from the host cell with it. And the virus – now carrying a protective coat – will attempt to infect another lung cell or be released into the air as we breathe or cough. </p>
<h2>Disrupting the virus</h2>
<p>Biochemists in a team led by Valerie O’Donnell at Cardiff University are trying <a href="https://doi.org/10.1093/function/zqaa002">to find out more about this bilayer</a> with the hope that drugs could be designed to combat the virus itself. By growing the COVID virus in the laboratory and extracting the lipid from it, they have found that its surface membrane is very different from that of the host surface membrane – it has much less cholesterol and sphingomyelin (a fatty lipid component) and many more lipids which can increase blood clotting.</p>
<p>When we look at the way the virus acquires its membrane, a number of drugs might be used to disrupt its pathway. This has been done before. Scientists working with <em>tubercle bacilli</em> in the 1950s showed that certain harmless detergents disrupted the tuberculosis infection they cause. With COVID, <a href="https://theconversation.com/yes-washing-our-hands-really-can-help-curb-the-spread-of-coronavirus-132915">widespread handwashing</a>, using hand sanitiser and mouth washing attacked the virus’ bilayer and destroyed it.</p>
<p>Perhaps the virus will produce, by mutation, a new strain that has a tougher bilayer. The Cardiff laboratory is looking into the lipid composition of different strains and the results may indicate novel pathways for evolution of viruses and their treatment.</p>
<h2>Other roles for bilayers</h2>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/491707/original/file-20221025-23-poplij.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/491707/original/file-20221025-23-poplij.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=553&fit=crop&dpr=1 600w, https://images.theconversation.com/files/491707/original/file-20221025-23-poplij.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=553&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/491707/original/file-20221025-23-poplij.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=553&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/491707/original/file-20221025-23-poplij.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=694&fit=crop&dpr=1 754w, https://images.theconversation.com/files/491707/original/file-20221025-23-poplij.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=694&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/491707/original/file-20221025-23-poplij.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=694&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Schistosoma larvae change to survive in human blood.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/microscopic-photo-schistosoma-worm-causative-agent-2082244726">Mohammed_Al_Ali/Shutterstock</a></span>
</figcaption>
</figure>
<p>Bilayers are also involved in the infection of humans by diseases <a href="https://doi.org/10.1017/S003118200999093X">such as schistosomiasis</a> (also known as bilharzia). Infective larvae swimming in water penetrate human skin and the bilayer on the larval surface immediately changes to a unique double layer to allow it to survive in human blood. The larvae then covers itself with lipids from this blood and scientists <a href="https://doi.org/10.3389/fimmu.2020.624178">have suggested</a> that this disguises the membrane from the immune response of hosts – in other words, us. </p>
<p>Another hypothesis put forward by scientists in Egypt about the toughness of this double bilayer comes <a href="https://doi.org/10.29245/2689-9981/2018/3.1127">from the amount of sphingomyelin</a>, which they found protects the membrane by forming hydrogen bonds at the surface. This is thought to prevent access to immune antibodies and cells. Reducing the amount of sphingomyelin with <a href="https://www.kcbd.com/story/1467213/arachidonic-acid-the-good-and-bad/">arachidonic acid</a> – a fatty acid found in the body and also used in some supplements – can act as a drug against the disease. It is usually used in combination with <a href="https://doi.org/10.1186/s12879-020-05053-z">another drug called praziquantel</a> which attacks the parasite’s membrane.</p>
<p>One exception to the generalisation that bilayers are in all living cells are the parasitic and soil nematodes. Enormous numbers of these are found in soil: ones that do not affect other plants or animals such as <a href="https://www.yourgenome.org/facts/why-use-the-worm-in-research"><em>Caenorhabditis</em></a>, but also <a href="https://doi.org/10.3389/fpls.2019.01165">numerous</a> other animal and plant parasitic <a href="https://doi.org/10.3389/fpls.2019.01165">species</a> in the tropics and temperate zones. These organisms have a surface in which lipids are thought to be <a href="https://doi.org/10.3389/fpls.2013.00494">arranged in unusual hexagonal</a> structures to form <a href="https://doi.org/10.3389/fmicb.2021.631274">large rafts</a> which give an alternative structure to the bilayer found in most cells.</p>
<p>Study of lipids can surprise us and lead to new ideas about life and its structure, but also, excitingly, towards drugs that can be developed to disturb the structure of the lipid membranes of pathogens, cancers and other human infections.</p><img src="https://counter.theconversation.com/content/178577/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>John Kusel does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Cell membranes are a basic structure common to most living organisms – but they can be hijacked.John Kusel, Emeritus professor of cellular biochemistry, University of GlasgowLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1922052022-10-19T15:24:26Z2022-10-19T15:24:26ZA dog parasite could help fight incurable cancers – what our immunotherapy research revealed<figure><img src="https://images.theconversation.com/files/488969/original/file-20221010-13-yr35lq.jpg?ixlib=rb-1.1.0&rect=0%2C90%2C3792%2C2276&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Identified in boxer dogs in 1984, the parasite _Neospora caninum_ is harmless to humans, yet has been shown to be effective against tumour cells in mice.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Cancers are the <a href="https://www.who.int/health-topics/cancer">second leading cause of death in the world</a>, after <a href="https://ourworldindata.org/causes-of-death#what-do-people-die-from">cardiovascular diseases</a>. Their seriousness lies in their diversity – some can be effectively treated with surgery, chemotherapy and radiotherapy, while others respond poorly or not at all. Improving the treatment of these diseases is therefore a major challenge.</p>
<p>For several years, the development of immunotherapies – treatments that use various components of the immune system to fight tumours – has offered hope. Some use modified viruses, but these can cause adverse effects for patients. </p>
<p>To overcome this problem, our team studied the possibility of instead using the microorganism <em>Neospora caninum</em>. Harmless to humans, this parasite is found in dogs. The first results of our research, obtained in mice, are encouraging. </p>
<h2>First immunotherapies: a positive impact</h2>
<p>Chemotherapy and radiotherapy prevent the multiplication of tumour cells but also attack non-cancerous cells, and so have serious side effects. In contrast, immunotherapy stimulates the patient’s immune system to target cancerous cells. Different strategies are employed, from the use of antibodies that target cancer cells or that prevent them from inactivating the immune system (known as <a href="https://www.cancer.gov/publications/dictionaries/cancer-terms/def/immune-checkpoint-inhibitor">immune checkpoint inhibitors</a>), to the use of live micro-organisms that induce a strong immune response to destroy tumour cells.</p>
<p>Immunotherapeutic approaches have been used since 2001 to treat melanoma: the development of the first immune checkpoint inhibiting antibody has resulted in more than <a href="https://doi.org/10.1016/S1470-2045(16)30366-7">53.6% of treated patients surviving two years</a>. In 2015, another advance in the management of melanoma resulted in <a href="https://doi.org/10.1016/j.critrevonc.2022.103705">shrinking tumours and increasing survival</a> rates. It is based on the use of a herpes virus modified to multiply in tumour cells and cause their death.</p>
<p>Immunotherapies could be the key to treating cancers that are currently incurable. Examples include glioblastoma, a serious brain cancer with an average survival of <a href="http://dx.doi.org/10%E2%80%8B.15586/codon.glioblastoma.2017.ch8">15 months</a> after diagnosis, and pancreatic cancer, which has an average survival of <a href="https://pancreatica.org/pancreatic-cancer/pancreatic-cancer-prognosis/">8 months</a>.</p>
<h2>A micro-organism as a new therapeutic hope?</h2>
<p><em>N. caninum</em> is a single-celled parasite that can cause severe neurological disease and foetal death in some animals (<a href="https://www.msdvetmanual.com/generalized-conditions/neosporosis/neosporosis-in-animals">cattle and canines</a>). However, it’s completely harmless to humans and most rodents, probably due to differences in immune responses. At the same time, <em>N. caninum</em> is able to multiply <em>in vitro</em> in cells of human or mouse origin.</p>
<p>Like the viruses used in immunotherapy, <em>N. caninum</em> can destroy the cells it infects and also induces a <a href="https://doi.org/10.1006/expr.1996.4110">strong immune response</a>. These two characteristics make it a good candidate for antitumour immunotherapy.</p>
<p>With this in mind, we decided to test its ability to treat mice for a cancer of the thymus (a gland located in the upper part of the thorax) called <a href="https://theoncologist.onlinelibrary.wiley.com/doi/full/10.1634/theoncologist.11-8-887">thymoma</a>. This type of cancer is mostly treated by surgery in humans. The goal was to demonstrate the anticancer efficacy of <em>N. caninum</em> before testing it on cancers that are resistant to existing treatments.</p>
<p>Our results, published in the <em>Journal for ImmunoTherapy of Cancer</em>, demonstrate that, in mice, <em>N. caninum</em> is able to control tumour development <a href="https://jitc.bmj.com/content/8/2/e001242">until complete regression</a>. These results were obtained not only after the (unmodified) microorganisms were administered directly into the tumour, but also at a distance from it.</p>
<h2>Three mechanisms for controlling tumour development</h2>
<p><em>N. canium</em> is able to control tumour development in three different ways. First, it can destroy cancer cells directly. Four days after treatment, <a href="https://www.genome.gov/genetics-glossary/Vacuole">vacuoles</a> (small compartments within cells) containing the <em>N. caninum</em> were observed in the tumour cells. Formed by the micro-organism, the compartments allow it to multiply in the host cell while being protected from degradation. After the multiplication stage, the parasitised cell is destroyed.</p>
<p>The observation of such vacuoles in the tumour means that <em>N. caninum</em> is indeed capable of multiplying in cancer cells and then destroying them. <em>N. caninum</em> has been detected in other cells, but without persisting or causing damage.</p>
<p>The second way in which <em>N. caninum</em> controls tumour development is through the stimulation of a cellular immune response. This response is characterised by high levels of inflammatory molecules as well as the recruitment of immune cells specialised in destroying cancer cells, whether or not they are infected with <em>N. caninum</em>. These cells are the cytotoxic <a href="https://www.cancer.gov/publications/dictionaries/cancer-terms/def/t-lymphocyte">T lymphocytes</a> and the <a href="https://www.cancer.gov/publications/dictionaries/cancer-terms/def/natural-killer-cell">natural killer cells</a> (NK), whose particularity is to produce proteins that degrade cell membranes, leading to the cell destruction.</p>
<p>Finally, <em>N. caninum</em> affects tumour development via reprogramming of the tumour microenvironment. Tumours grow in part because they are able to “sedate” the immune system, forming a so-called <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6200899/">immunosuppressive microenvironment</a>, which favours their development. Tumours do so by producing molecules such as VEGF (<em>vascular endothelial growth factor</em>), a protein involved in the creation of blood vessels that bring nutrients to the tumour, and is PD-L1 (<em>programmed death-Ligand 1</em>), which prevents the death of cells that express it strongly.</p>
<p>After treatment with <em>N. caninum</em>, however, these two molecules are produced at lower levels within the tumour. This decrease in concentration makes it possible to reprogram the tumour microenvironment so that it participates in the elimination of the cancer cells.</p>
<h2>Promising preliminary results</h2>
<p>Obtained in mice, these results are preliminary but very encouraging. They show that <em>N. caninum</em> could be a good candidate to enrich the arsenal of anti-cancer immunotherapies.</p>
<p>Using a micro-organism to treat cancer was a gamble because it has the ability to multiply in cells. However, at the end of our experiments, <em>N. caninum</em> was no longer detectable in the treated mice. Although humans are not susceptible to infection with <em>N. caninum</em>, its elimination by the immune system will have to be confirmed before it can be used therapeutically. Having demonstrated its efficacy in a benign cancer model, the next step is to study the anti-cancer properties of <em>N. caninum</em> in difficult-to-treat cancers.</p><img src="https://counter.theconversation.com/content/192205/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Les auteurs ne travaillent pas, ne conseillent pas, ne possèdent pas de parts, ne reçoivent pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'ont déclaré aucune autre affiliation que leur organisme de recherche.</span></em></p>New research has found that a parasite first identified in dogs could help stimulate the human immune system to attack cells of cancerous tumours.Arthur Battistoni, Doctorant, équipe BioMAP UMR ISP 1282, Université de ToursFrançoise Debierre-Grockiego, Enseignant chercheur, Université de ToursLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1902962022-10-13T12:23:17Z2022-10-13T12:23:17ZBees face many challenges – and climate change is ratcheting up the pressure<figure><img src="https://images.theconversation.com/files/489384/original/file-20221012-18-sw1rgp.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5184%2C3880&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Bees look for water on an outdoor tap in Berlin, Germany during a hot spell, June 19, 2022.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/berlin-bees-try-to-take-water-from-the-thread-of-an-old-tap-news-photo/1241401800">Wolfram Steinberg/picture alliance via Getty Images</a></span></figcaption></figure><p>The extreme weather that has <a href="https://theconversation.com/looking-back-on-americas-summer-of-heat-floods-and-climate-change-welcome-to-the-new-abnormal-190636">battered much of the U.S.</a> in 2022 doesn’t just affect humans. Heat waves, wildfires, droughts and storms also <a href="https://www.fws.gov/initiative/impacts">threaten many wild species</a> – including some that already face other stresses. </p>
<p>I’ve been <a href="https://scholar.google.com/citations?hl=en&user=B1qAtjIAAAAJ">researching bee health</a> for over 10 years, with a focus on honey bees. In 2021, I began hearing for the first time from beekeepers about how extreme drought and rainfall were affecting bee colony health. </p>
<p><a href="https://www.ncei.noaa.gov/access/monitoring/monthly-report/drought/202113">Drought conditions in the western U.S.</a> in 2021 dried up bee forage – the floral nectar and pollen that bees need to produce honey and stay healthy. And <a href="https://www.washingtonpost.com/weather/2021/12/29/wettest-2021-east-us/">extreme rain in the Northeast</a> limited the hours that bees could fly for forage. </p>
<p>In both cases, managed colonies – hives that humans keep for honey production or commercial pollination – were starving. Beekeepers had to feed their bees more supplements of sugar water and pollen than they usually would to keep their colonies alive. Some beekeepers who had been in business for decades shared that they lost 50% to 70% of their colonies over the winter of 2021-2022. </p>
<p>These weather conditions <a href="https://doi.org/10.1093/jisesa/ieaa114">likely also affected wild and native bees</a>. And unlike managed colonies, these important species did not receive supplements to buffer them through harsh conditions. </p>
<p>Each year, the <a href="https://www.usda.gov/">U.S. Department of Agriculture</a> and the <a href="https://www.epa.gov/">Environmental Protection Agency</a> host federal pollinator experts to share the latest scientific findings on bee and pollinator health, and assess the status of these important insects, birds, bats and other species. One clear takeaway from this year’s meeting was that climate change has become a new and formidable stressor for bees, potentially amplifying previously known issues in ways that scientists can’t yet predict but need to prepare for. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/6tZTH5KWFqM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Climate change threatens bees around the world. In Australia, large-scale bushfires and drought have killed millions of bees in recent years.</span></figcaption>
</figure>
<h2>The scourge of <em>Varroa</em> mites</h2>
<p>Pollinators contribute <a href="https://ipbes.net/article/press-release-pollinators-vital-our-food-supply-under-threat">an estimated US$235 billion to $577 billion</a> yearly to global agriculture, based on the value of the crops they pollinate. Understanding and mitigating the impacts of climate change on pollinators is key for supporting healthy ecosystems and sustainable agriculture.</p>
<p>Bee health first attracted widespread attention in 2006 with the emergence of <a href="https://www.epa.gov/pollinator-protection/colony-collapse-disorder">Colony Collapse Disorder</a>, a phenomenon where the majority of adult worker bees in a colony disappeared, leaving their honey and pollen stores and some nurse bees behind to care for the queen and remaining immature bees. In the past five years, reported cases have declined substantially. Now, researchers are focusing on what beekeepers call the “four Ps”: parasites, pathogens, pesticides and poor nutrition, as well as habitat loss for wild and native bees. </p>
<p>One of the most severe threats to honey bees over the past several decades has been <em>Varroa destructor</em>, a crablike parasitic mite that <a href="https://doi.org/10.1073/pnas.1818371116">feeds on honey bees’ fat body tissue</a>. The fat body is <a href="https://entomologytoday.org/2019/02/21/inside-look-how-varroa-mite-diet-discovered/">a nutrient-dense organ</a> that functions much like the liver in mammals. It helps bees maintain a strong immune system, metabolize pesticides and survive through the winter. </p>
<p>These are vital functions, so controlling mite infestations is essential for bee health. <em>Varroa</em> can also transmit deadly pathogens to honey bees, such as <a href="https://doi.org/10.1038/s41598-019-47447-3">deformed wing virus</a>. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/489395/original/file-20221012-21-7erbs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A bee flying, with two brown circular mites clinging to it" src="https://images.theconversation.com/files/489395/original/file-20221012-21-7erbs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/489395/original/file-20221012-21-7erbs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=516&fit=crop&dpr=1 600w, https://images.theconversation.com/files/489395/original/file-20221012-21-7erbs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=516&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/489395/original/file-20221012-21-7erbs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=516&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/489395/original/file-20221012-21-7erbs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=648&fit=crop&dpr=1 754w, https://images.theconversation.com/files/489395/original/file-20221012-21-7erbs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=648&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/489395/original/file-20221012-21-7erbs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=648&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A honey bee carrying two <em>Varroa</em> mites, one above its leg and one on its back.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/2hcd9TT">USGS</a></span>
</figcaption>
</figure>
<p>Controlling mite populations is challenging. It requires using an insecticide in an insect colony, or as beekeepers say, “trying to kill a bug on a bug.” It’s hard to find a formula strong enough to kill mites without harming the bees. </p>
<p>Monitoring <em>Varroa</em> takes significant skill and labor, and mites can build up resistance to treatments over time. Researchers and beekeepers are working hard to <a href="https://www.sare.org/publications/a-sustainable-approach-to-controlling-honey-bee-diseases-and-varroa-mites/breeding-for-resistance/">breed <em>Varroa</em>-resistant bees</a>, but mites continue to plague the industry.</p>
<h2>Pesticide microdoses</h2>
<p>Pesticides also harm bees, particularly products that cause sublethal or chronic bee health issues. <a href="https://doi.org/10.1016/j.scitotenv.2022.156857">Sublethal pesticide exposures</a> can make bees less able to <a href="https://doi.org/10.1111/1365-2435.12292">gather forage</a>, <a href="https://doi.org/10.1371/journal.pone.0077547">grow healthy larvae</a> and <a href="https://doi.org/10.1016/j.cois.2018.01.006">fight off viruses</a> and mites. </p>
<p>However, it can be hard to document and understand sublethal toxicity. Many factors affect how bees react to agrochemicals, including whether they are exposed as larvae or as adult bees, the mixture of chemicals bees are exposed to, the weather at the time of application and how healthy a bee colony is pre-exposure.</p>
<p>Researchers are also working to understand <a href="https://theconversation.com/a-common-soil-pesticide-cut-wild-bee-reproduction-by-89-heres-why-scientists-are-worried-155985">how soil pesticides affect ground-nesting wild bees</a>, which represent <a href="https://ento.psu.edu/research/centers/pollinators/resources-and-outreach/disappearing-pollinators/nesting-sites">over 70% of the U.S. native bee</a> population. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/487116/original/file-20220928-6297-s2i3ld.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A bee crawls out of a small hole in the dirt, overhung by grass" src="https://images.theconversation.com/files/487116/original/file-20220928-6297-s2i3ld.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/487116/original/file-20220928-6297-s2i3ld.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=568&fit=crop&dpr=1 600w, https://images.theconversation.com/files/487116/original/file-20220928-6297-s2i3ld.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=568&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/487116/original/file-20220928-6297-s2i3ld.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=568&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/487116/original/file-20220928-6297-s2i3ld.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=714&fit=crop&dpr=1 754w, https://images.theconversation.com/files/487116/original/file-20220928-6297-s2i3ld.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=714&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/487116/original/file-20220928-6297-s2i3ld.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=714&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A ground-nesting bee (<em>Colletes inaqualis</em>) emerging from its burrow.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/9GUDGz">Rob Cruickshank/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Junk food diets</h2>
<p>Like many other species, bees are losing the habitat and food sources that they depend on. This is happening <a href="https://ento.psu.edu/research/centers/pollinators/resources-and-outreach/disappearing-pollinators/habitat-fragmentation">for many reasons</a>. </p>
<p>For example, uncultivated lands are being <a href="https://doi.org/10.1038/s41467-021-22702-2">converted to farmland or developed worldwide</a>. Large-scale agriculture focuses on mass production of a few commodity crops, which reduces the amount of nesting habitat and forage available for bees. </p>
<p>And many farmers often remove pollinator-friendly plants and shrubs that grow around farm lands to reduce the risk of attracting animals such as deer and rodents, which could <a href="https://doi.org/10.1093/biosci/biv152">spread pathogens that cause foodborne illness</a>. Research suggests that these efforts <a href="https://doi.org/10.1111/1365-2664.12707">harm beneficial insects and don’t increase food safety</a>. </p>
<p>As diverse and healthy bee forage disappears, beekeepers <a href="https://doi.org/10.1016/j.jrurstud.2018.10.007">feed their bees more supplements</a>, such as sugar water and pollen substitutes, which are <a href="https://doi.org/10.1007/s13592-015-0386-6">not as nutritious</a> as the nectar and pollen bees get from flowers.</p>
<h2>Climate change is a force multiplier</h2>
<p>Researchers don’t know exactly how climate change will affect bee health. But they suspect it will add to existing stresses. </p>
<p>For example, if pest pressures mount for farmers, bees will be exposed to more pesticides. Extreme rainfall can <a href="https://doi.org/10.1007/s11829-019-09686-z">disrupt bees’ foraging patterns</a>. Wildfires and floods may destroy bee habitat and food sources. Drought may also <a href="https://doi.org/10.1111/gcb.14130">reduce available forage</a> and <a href="https://doi.org/10.3389/fsufs.2021.628802">discourage land managers</a> from planting new areas for bees as water becomes less readily available. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1062404727995011077"}"></div></p>
<p>Climate change could also increase the spread of <em>Varroa</em> and other pathogens. Warmer fall and winter temperatures <a href="https://doi.org/10.21203/rs.3.rs-1394621/v1">extend the period when bees forage</a>. <em>Varroa</em> travel on foraging bees, so longer foraging provides a larger time window for mites and the viruses they carry to spread among colonies. Higher mite populations on bee colonies heading into winter will likely cripple colony health and <a href="https://doi.org/10.1371/journal.pone.0159615">increase winter losses</a>.</p>
<p>Studies have already shown that climate change is <a href="https://doi.org/10.1042/ETLS20190139">disrupting seasonal connections</a> between bees and flowers. As spring arrives earlier in the year, <a href="https://doi.org/10.1098/rspb.2019.0573">flowers bloom earlier</a> or in different regions, but bees may not be present to feed on them. Even if flowers bloom at their usual times and locations, they may <a href="https://doi.org/10.1016/j.cois.2022.100927">produce less-nutritious pollen and nectar</a> under extreme weather conditions. </p>
<p>Research that analyzes the nutritional profiles of bee forage plants and how they change under different climate scenarios will help land managers plant climate-resilient plants for different regions. </p>
<h2>Creating safe bee spaces</h2>
<p>There are many ways to support bees and pollinators. Planting <a href="https://theconversation.com/urban-gardens-are-crucial-food-sources-for-pollinators-heres-what-to-plant-for-every-season-174552">pollinator gardens</a> with regional plants that bloom throughout the year can provide much-needed forage. </p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/reel/Cg8BHF_DOud/?utm_source=ig_web_copy_link","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>Ground-nesting native bees need patches of exposed and undisturbed soil, free of mulch or other ground covers. Gardeners can clear some ground in a sunny, well-drained area to create <a href="https://xerces.org/blog/ground-nesting-bees#:%7E:text=If%20you'd%20like%20to,growing%20plants%20to%20prevent%20erosion">dedicated spaces for bees to dig nests</a>. </p>
<p>Another important step is using <a href="https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=17624">integrated pest management</a>, a land management approach that minimizes the use of chemical pesticides. And anyone who wants to help monitor native bees can join <a href="https://xerces.org/community-science">community science projects</a> and use phone apps to submit data. </p>
<p>Most importantly, educating people and communities about bees and their importance to our food system can help create a more pollinator-friendly world.</p><img src="https://counter.theconversation.com/content/190296/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr. Jennie L. Durant has received funding from the U.S. Department of Agriculture's National Institute of Food and Agriculture. She was a AAAS Science and Technology Fellow at the U.S. Department of Agriculture from 2021-2022.</span></em></p>Honey bees, wild and native bees face threats from parasites, pesticides and habitat loss. Shorter winters, more extreme weather and more habitat destruction won’t help.Jennie L. Durant, Research Affiliate in Human Ecology, University of California, DavisLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1872552022-08-15T02:57:13Z2022-08-15T02:57:13ZWhy do my kids keep getting worms? And is that what is making them so cranky?<figure><img src="https://images.theconversation.com/files/478227/original/file-20220809-18-soyxhr.jpg?ixlib=rb-1.1.0&rect=32%2C40%2C5431%2C3596&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>As a parent, it might feel like you are constantly giving your children worm treatments – usually in the form of chocolate or sweetened chewable tablets. </p>
<p>In fact, most kids in Australia (or any other rich country) get very few worms compared to kids in places where poor hygiene practices make all sorts of worms common. But there is one species of worm so common and so tied to humanity, it can defeat even our most comprehensive hygiene standards. </p>
<p>Young children are really good at transmitting infection with these tiny pests. And they can get really cranky in the process.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-are-parasites-and-how-do-they-make-us-sick-121489">What are parasites and how do they make us sick?</a>
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<h2>An ancient species</h2>
<p>Pinworms are an ancient species and have been found in fossilised 230-million-year-old <a href="https://doi.org/10.1186/s13071-014-0486-6">proto mammalian poo</a>. The closest relatives of the pinworm humans get are found in our closest cousins, <a href="http://dx.doi.org/10.1051/parasite/1999063201">the apes</a>. Our pinworms are thought to have evolved with us. The oldest pinworm eggs from a human host were found in some <a href="https://www.science.org/doi/10.1126/science.166.3913.1620">10,000-year-old</a> dried human stools discovered in a Colorado cave. So, pinworms are very well adapted to living in and with humans.</p>
<p>Pinworm infection is present in <a href="https://www.aerzteblatt.de/int/archive/article/206305">between 5%</a> and <a href="https://www.cdc.gov/parasites/pinworm/epi.html">up to 50%</a> of primary school children, though easy access to good treatments and <a href="https://www.ajtmh.org/view/journals/tpmd/65/5/article-p558.xml">school education programs</a> have reduced levels over the last 20 to 30 years.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/478220/original/file-20220809-24-4tu41.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="microscopic worm" src="https://images.theconversation.com/files/478220/original/file-20220809-24-4tu41.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/478220/original/file-20220809-24-4tu41.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/478220/original/file-20220809-24-4tu41.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/478220/original/file-20220809-24-4tu41.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/478220/original/file-20220809-24-4tu41.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/478220/original/file-20220809-24-4tu41.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/478220/original/file-20220809-24-4tu41.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Pinworm under the microscope.</span>
<span class="attribution"><a class="source" href="https://image.shutterstock.com/image-photo/strongyloides-stercoralis-threadworm-stool-analyze-600w-508000876.jpg">Shutterstock</a></span>
</figcaption>
</figure>
<p>These worms are white and thread-like with females <a href="https://www.cdc.gov/parasites/pinworm/">measuring up to 13 milimetres long</a>. Males are less than half that size. They live in humans worldwide, mostly in children between four and 11 years old. They can also <a href="https://www.aerzteblatt.de/int/archive/article/206305">infect adults</a> though usually with less negative effects. </p>
<p>Pinworms have been associated with some other conditions including types of <a href="https://doi.org/10.1371/journal.pone.0232143">appendicitis</a>, <a href="https://doi.org/10.1111/j.1365-4632.2004.02332.x">vaginitis and urethral infections</a> but these are not common outcomes.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/love-the-parasite-youre-with-the-entertaining-life-of-unwelcome-guests-from-flea-circuses-to-aliens-137602">Love the parasite you're with - the entertaining life of unwelcome guests from flea circuses to Aliens</a>
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</p>
<hr>
<h2>The egg problem</h2>
<p>The problem isn’t usually the adult worms, which live in the caecum (a pouch where the small and large intestines meet) for up to two months. </p>
<p>When the female wriggles out of the gut to lay her eggs <a href="https://www.cdc.gov/parasites/pinworm/">around the anus</a> – usually early in the morning – it can cause irritation. But the biggest issue is caused by eggs that are stuck onto the perianal skin with an irritating glue. This is what causes even more irritation and itching. </p>
<p>The worm’s life cycle actually depends on the child or adult scratching their bum. When the eggs are scratched off onto the hands or under the nails they can be transferred to other children at home or at school, or to adults. Most often they go to the scratching child’s mouth where they can be swallowed and start another infection, known as an “auto infection”. </p>
<p>The eggs are so light they can infest pyjamas, bed clothes, the bedroom and in long term infections they are found in <a href="https://pubmed.ncbi.nlm.nih.gov/21286054/">house dust</a> (though studies suggest these eggs are <a href="https://www.aerzteblatt.de/int/archive/article/206305">not viable beyond one week</a>).</p>
<p>Pinworm eggs are literally a pain. They can make a child scratch so much they cause skin inflammation called <a href="https://journals.lww.com/jpgn/Fulltext/2009/05000.aspx">puritis</a>. This becomes very painful and can result in lost sleep and a <a href="https://www.cdc.gov/parasites/pinworm/">very tired and cranky child</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/478223/original/file-20220809-14-qqm53q.jpg?ixlib=rb-1.1.0&rect=1190%2C23%2C3347%2C2875&q=45&auto=format&w=1000&fit=clip"><img alt="two kids in airport scratching bottoms" src="https://images.theconversation.com/files/478223/original/file-20220809-14-qqm53q.jpg?ixlib=rb-1.1.0&rect=1190%2C23%2C3347%2C2875&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/478223/original/file-20220809-14-qqm53q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=343&fit=crop&dpr=1 600w, https://images.theconversation.com/files/478223/original/file-20220809-14-qqm53q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=343&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/478223/original/file-20220809-14-qqm53q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=343&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/478223/original/file-20220809-14-qqm53q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=432&fit=crop&dpr=1 754w, https://images.theconversation.com/files/478223/original/file-20220809-14-qqm53q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=432&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/478223/original/file-20220809-14-qqm53q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=432&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Pinworm infection can cause intense itching.</span>
<span class="attribution"><a class="source" href="https://image.shutterstock.com/image-photo/denver-colorado-9252021-woman-two-600w-2062641551.jpg">Shutterstock</a></span>
</figcaption>
</figure>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/one-in-three-people-are-infected-with-toxoplasma-parasite-and-the-clue-could-be-in-our-eyes-182418">One in three people are infected with _Toxoplasma_ parasite – and the clue could be in our eyes</a>
</strong>
</em>
</p>
<hr>
<h2>So that’s what’s up with them …</h2>
<p>There are many reasons for a child to be tired and cranky. But if your primary school age child is behaving this way and has an itchy bum, pinworm may be the culprit. </p>
<p>Pinworm eggs are so small they can’t be seen individually but the females lay more than <a href="https://www.aerzteblatt.de/int/archive/article/206305">10,000 in creamy coloured clumps</a>, which may be visible around the anus. The female is also visible when laying eggs, which means a check of your child’s bottom when they are itching intensely may be revealing. Otherwise a sticky tape swab of the skin next to the anus can be analysed for eggs under a microscope. Your doctor can organise such a test. </p>
<p>Treatment is simple and easily obtained from the chemist. Most worming brands use the same drug, called <a href="https://search.informit.org/doi/10.3316/informit.464588837788277">mebendazole</a>. Medication should be taken by each member of the family and the dose should be repeated two weeks later to ensure control of pinworm in the home. Contaminated clothing and bedding should be washed in hot water. </p>
<p>Other methods of <a href="https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/pinworms">preventing infection</a> include regularly washing hands and scrubbing finger nails. A shower with a good bum wash is also a good idea, especially in the morning. Trying to stop children sucking their fingers and thumbs, sucking toys or other items that might carry eggs is also suggested, though not easily achieved.</p>
<p>Although we have better control of pinworms in the 21st century, they are still with us and we are very unlikely to be able to eradicate such a well-adapted and intimately entwined parasite.</p><img src="https://counter.theconversation.com/content/187255/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mark Sandeman does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>A large proportion of primary school aged kids get infected with pinworm at some time – and yes, it can make them pretty moody.Mark Sandeman, Honorary Professor, Federation University AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1794302022-06-03T12:17:46Z2022-06-03T12:17:46ZBed bugs’ biggest impact may be on mental health after an infestation of these bloodsucking parasites<figure><img src="https://images.theconversation.com/files/466798/original/file-20220602-24-e1ajb7.jpg?ixlib=rb-1.1.0&rect=597%2C134%2C1546%2C704&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Dozens of bed bugs and their eggs and fecal material on a metal bed frame.</span> <span class="attribution"><span class="source">Jerome Goddard</span></span></figcaption></figure><p>Bed bugs are back with a vengeance. After an absence of around 70 years, thanks to effective pesticides such as DDT, they’ve been popping up in fancy hotels, spas, department stores, subway trains, movie theaters – and, of course, people’s homes.</p>
<p><a href="https://scholar.google.com/citations?user=JVfeckwAAAAJ&hl=en&oi=ao">I’m a public health entomologist</a>. In the course of my work, I’ve studied these little bloodsuckers, even letting bed bugs feast on my own appendages in the name of science. <a href="https://www.cc.com/video/5klha6/the-colbert-report-threatdown-bedbugs-environmentalists-jerome-goddard">No one likes dealing with bed bugs</a> – and there are ways to minimize your chances of needing to.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/466795/original/file-20220602-22-q1mksl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="closeup of the front underside of a brown insect" src="https://images.theconversation.com/files/466795/original/file-20220602-22-q1mksl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/466795/original/file-20220602-22-q1mksl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=408&fit=crop&dpr=1 600w, https://images.theconversation.com/files/466795/original/file-20220602-22-q1mksl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=408&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/466795/original/file-20220602-22-q1mksl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=408&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/466795/original/file-20220602-22-q1mksl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=513&fit=crop&dpr=1 754w, https://images.theconversation.com/files/466795/original/file-20220602-22-q1mksl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=513&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/466795/original/file-20220602-22-q1mksl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=513&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Colorized scanning electron microscopic image reveals the underside of a bed bug, including the proboscis (purple) and two eyes (red).</span>
<span class="attribution"><a class="source" href="https://phil.cdc.gov/Details.aspx?pid=11739">CDC/Janice Haney Carr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Know thy bed bug enemy</h2>
<p>The common bed bug, <em>Cimex lectularius</em>, has been a parasite of humans for thousands of years. Historically, these tiny bloodsuckers were common in human dwellings worldwide, giving the old saying “sleep tight, don’t let the bed bugs bite” real meaning. They had nearly disappeared in developing countries until the mid-1990s, when they began <a href="https://doi.org/10.1093/ae/52.2.102">making a comeback</a> because of restriction or loss of certain pesticides, changes in pest control practices and increased international travel. <a href="https://medent.usyd.edu.au/bedbug/papers/doggett_icup2008.pdf">In many areas</a> around the world, they are now <a href="https://npmapestworld.org/default/assets/File/publicpolicy/executivesummaryreleasetomembersFINAL.pdf">a major urban pest</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/455860/original/file-20220401-30316-7hdfi7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="brown insect on white human skin, eating" src="https://images.theconversation.com/files/455860/original/file-20220401-30316-7hdfi7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/455860/original/file-20220401-30316-7hdfi7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/455860/original/file-20220401-30316-7hdfi7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/455860/original/file-20220401-30316-7hdfi7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/455860/original/file-20220401-30316-7hdfi7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/455860/original/file-20220401-30316-7hdfi7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/455860/original/file-20220401-30316-7hdfi7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A bed bug extends its beaklike proboscis to feed on human blood.</span>
<span class="attribution"><span class="source">Jerome Goddard</span></span>
</figcaption>
</figure>
<p>Adult bed bugs are less than a quarter-inch long (about 5 mm), oval-shaped and flattened, resembling unfed ticks or small cockroaches. Tucked backward underneath their head they have a long proboscis – a tubular mouthpart they can extend to take a blood meal. A bed bug needs only between three and 10 minutes to <a href="http://ipm.ucanr.edu/PMG/PESTNOTES/pn7454.html">consume up to six times its weight in blood</a> in a single meal.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/455865/original/file-20220401-11604-l3fugz.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Small insect sits on a dime" src="https://images.theconversation.com/files/455865/original/file-20220401-11604-l3fugz.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/455865/original/file-20220401-11604-l3fugz.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=537&fit=crop&dpr=1 600w, https://images.theconversation.com/files/455865/original/file-20220401-11604-l3fugz.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=537&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/455865/original/file-20220401-11604-l3fugz.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=537&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/455865/original/file-20220401-11604-l3fugz.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=675&fit=crop&dpr=1 754w, https://images.theconversation.com/files/455865/original/file-20220401-11604-l3fugz.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=675&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/455865/original/file-20220401-11604-l3fugz.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=675&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A yellowish-white first-stage bed bug nymph is tiny.</span>
<span class="attribution"><span class="source">Jerome Goddard</span></span>
</figcaption>
</figure>
<p>Adults are reddish brown, while the babies are extremely tiny and yellowish-white in color. They hide in cracks and crevices, generally within a few feet of a bed, coming out only to feed on an unsuspecting host. Then they run back to their hiding places, where they mate and lay eggs. </p>
<p>Houses can become infested with thousands of the little bloodthirsty pests in the mattress and box spring, where they leave telltale black fecal spots. In severe infestations there may be thick feces, hundreds of shed skins and eggs several millimeters thick.</p>
<h2>Biggest health impacts may be psychological</h2>
<p>Bed bugs have been <a href="https://doi.org/10.2307/4591852">suspected in the transmission</a> of more than 40 disease organisms, but there is <a href="https://doi.org/10.1001/jama.2009.405">little evidence bed bugs transmit human pathogens</a>, with the <a href="https://doi.org/10.4269/ajtmh.14-0483">possible exception of the microorganism that causes Chagas disease</a>. Extreme infestations can, in rare cases, lead to <a href="https://doi.org/10.1503/cmaj.090482">blood loss severe enough to cause anemia</a>.</p>
<p>Their <a href="https://www.cdc.gov/parasites/bedbugs/faqs.html">principal medical impacts</a> are related to nuisance biting and the associated itching and inflammation. The most common bite reactions are <a href="https://doi.org/10.1016/j.parint.2006.12.002">itchy red spots at feeding sites</a> that usually go away in a week or so. Some people have <a href="https://pubmed.ncbi.nlm.nih.gov/11534921/">complex skin</a> <a href="https://doi.org/10.1007/978-1-4471-1356-0">reactions</a>, <a href="https://doi.org/10.4314/wajm.v21i4.27994">including hives</a> and <a href="https://doi.org/10.1016/j.amjmed.2011.11.020">blisters</a>, or allergic responses.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/455870/original/file-20220401-11-2vzeac.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="pink irritated patch on white skin of an arm" src="https://images.theconversation.com/files/455870/original/file-20220401-11-2vzeac.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/455870/original/file-20220401-11-2vzeac.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/455870/original/file-20220401-11-2vzeac.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/455870/original/file-20220401-11-2vzeac.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/455870/original/file-20220401-11-2vzeac.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/455870/original/file-20220401-11-2vzeac.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/455870/original/file-20220401-11-2vzeac.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The marks from bed bug bites can persist on human skin for several days.</span>
<span class="attribution"><span class="source">Jerome Goddard and Kristine T. Edwards</span></span>
</figcaption>
</figure>
<p>Then there’s bed bugs’ <a href="http://dx.doi.org/10.1136/bmjopen-2012-000838">emotional and</a> <a href="https://doi.org/10.1016/j.amjmed.2011.08.010">psychological effects on their victims</a>. Run-ins with these parasites can trigger nervousness, anxiety and insomnia. Bed bugs commonly come with a side effect of constant worrying and feelings of shame. <a href="http://habitatservices.org/wp-content/uploads/PDF3-Bed-Bugs-Are-Back-Report.pdf">One distressed Canadian expressed it this way</a>:</p>
<blockquote>
<p>“To be honest, until you go through [an infestation], you have no idea just how horrifying it really is. It is just natural for you to become paranoid; you lose sleep, you end up dreaming and thinking about bed bugs – they just consume every fiber of your being.”</p>
</blockquote>
<p><a href="http://hdl.handle.net/1866/10783">One study of people exposed to bed bugs</a> found about half reported sleep difficulties and social isolation associated with the infestation.</p>
<p>My colleague and I analyzed <a href="https://doi.org/10.1016/j.amjmed.2011.08.010">135 internet posts concerning bed bug infestations</a>. The majority, 81% of the posts, reported three or more behaviors commonly associated with post-traumatic stress disorder – reactions like reexperiencing the event through intrusive memories and nightmares, startle responses and hypervigilance. Six posts detailed intense and repeated cleanings of homes or offices. Five posts reported persistent avoidance of people, activities and places that might lead to transmission of insects or arouse recollections of the original encounter. And five posts detailed suicidal thoughts or attempts. There are other anecdotal reports of <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3700489/">suicides</a> or drug overdoses by people struggling with bed bugs.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/455868/original/file-20220401-19-26i6dl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Bed bugs and fecal spots on a bed sheet." src="https://images.theconversation.com/files/455868/original/file-20220401-19-26i6dl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/455868/original/file-20220401-19-26i6dl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/455868/original/file-20220401-19-26i6dl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/455868/original/file-20220401-19-26i6dl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/455868/original/file-20220401-19-26i6dl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/455868/original/file-20220401-19-26i6dl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/455868/original/file-20220401-19-26i6dl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">You can check for the telltale marks of a bed bug infestation on a bed’s mattress and box spring.</span>
<span class="attribution"><a class="source" href="https://www.acq.osd.mil/eie/afpmb/docs/techguides/tg44.pdf">H.J. Harlan, U.S. Armed Forces Pest Management Board</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>How to protect yourself from bed bugs</h2>
<p>Not every hotel room has bed bugs, but some do. Simple precautions can help protect you and your belongings from infestation. </p>
<p>Leave all unnecessary items in your vehicle, such as extra clothing, gear and equipment. When first entering your hotel room, place luggage in the bathroom until you have had a chance to inspect the place. Pull back sheets and check the mattress and box spring for live bed bugs or black fecal spots. If any bugs or suspicious signs of infestation are found, go to the front desk and request another room. Because bed bugs don’t usually travel far on their own, other nonadjacent rooms may be perfectly clean of the parasites.</p>
<p>Keeping bed bugs out of houses and apartments can be difficult, especially if you travel a lot. After traveling, unpack luggage outside or in the garage, and wash all clothing from the luggage in hot water and dry on high heat if possible. A dryer is a great tool in the fight against bed bugs. Bed bugs can also hitch a ride into your home on used furniture or items purchased at secondhand stores or garage sales. Be sure to disinfect – more precisely “dis-insect” – those kinds of items. It’s a good idea to never purchase used mattresses or beds, no matter how good a bargain. </p>
<p>What can you do if you are forced to confront these bloodsuckers? A bed bug infestation found in a hotel room should immediately be reported to management. If you find bed bugs in your home, or in secondhand purchases, it’s best not to try to spray them yourself with over-the-counter pesticides. My recommendation is to contact a competent pest exterminator, who will treat the space with pesticides, use complex heat systems or both to kill the bugs.</p>
<p>Try not to panic. Keep in mind that bed bugs are only insects. They’re not magic. Believe me, they can be killed and eliminated from a dwelling.</p><img src="https://counter.theconversation.com/content/179430/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jerome Goddard does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Bed bugs are pretty much universally reviled. But a public health entomologist explains how – while potentially traumatizing to deal with – they aren’t likely to make you sick.Jerome Goddard, Extension Professor of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1824182022-05-11T19:55:43Z2022-05-11T19:55:43ZOne in three people are infected with ‘Toxoplasma’ parasite – and the clue could be in our eyes<figure><img src="https://images.theconversation.com/files/462178/original/file-20220510-20-i2xe1.jpg?ixlib=rb-1.1.0&rect=26%2C8%2C5964%2C3907&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://image.shutterstock.com/image-illustration/parasitic-protozoans-toxoplasma-gondii-causative-600w-2136137853.jpg">Shutterstock</a></span></figcaption></figure><p><em>Toxoplasma gondii</em> is probably the most successful parasite in the world today. This microscopic creature is capable of infecting any mammal or bird, and people across all continents are <a href="https://pubmed.ncbi.nlm.nih.gov/32717377/">infected</a>. Once infected, a person carries <em>Toxoplasma</em> for life. So far, we don’t have a drug that can eradicate the parasite from the body. And there is no vaccine approved for use in humans.</p>
<p>Across the world, it’s estimated <a href="https://pubmed.ncbi.nlm.nih.gov/22491772/">30–50% of people</a> are infected with <em>Toxoplasma</em> – and infections may be increasing in Australia. A survey of studies conducted at blood banks and pregnancy clinics across the country <a href="https://pubmed.ncbi.nlm.nih.gov/470719/">in the 1970s</a> put the infection rate at 30%. However, a recent Western Australian <a href="https://ro.ecu.edu.au/ecuworkspost2013/8534/">community-based study</a> found 66% of people were infected.</p>
<p>The disease caused by this parasite can scar the back of the eye. Our <a href="https://www.ophthalmologyretina.org/article/S2468-6530(22)00215-9/fulltext">new research</a> looked for signs of disease in otherwise healthy people and found a significant number bore the mark of <em>Toxoplasma</em>. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/cats-carry-diseases-that-can-be-deadly-to-humans-and-its-costing-australia-6-billion-every-year-147910">Cats carry diseases that can be deadly to humans, and it's costing Australia $6 billion every year</a>
</strong>
</em>
</p>
<hr>
<h2>We don’t just get it from cats</h2>
<p>The cat is the primary host for <em>Toxoplasma</em>. </p>
<p>Cats catch the parasite when they eat infected prey. Then, for a couple of weeks, they pass large numbers of parasites in their faeces in a form that can survive for long periods in the environment, even during extreme weather. </p>
<p>When the faeces are ingested by livestock while grazing, parasites lodge in the muscle and survive there after the animals are slaughtered for meat. Humans can become infected by eating this meat, or by eating fresh produce or drinking water soiled by cats. It is also possible for a woman infected for the first time during pregnancy to pass the infection to her unborn child.</p>
<p>While infection with <em>Toxoplasma</em> is extremely common, the most important health statistic is the rate of the disease caused by the infection, which is called toxoplasmosis. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/disease-causing-parasites-can-hitch-a-ride-on-plastics-and-potentially-spread-through-the-sea-new-research-suggests-181824">Disease-causing parasites can hitch a ride on plastics and potentially spread through the sea, new research suggests</a>
</strong>
</em>
</p>
<hr>
<h2>How it affects the eye</h2>
<p><em>Toxoplasma</em> <a href="https://pubmed.ncbi.nlm.nih.gov/32717377/">really likes the retina</a>, the multi-layered nerve tissue that lines the eye and generates vision. Infection can cause recurring attacks of retinal inflammation and <a href="https://pubmed.ncbi.nlm.nih.gov/22712598/">permanent retinal scarring</a>. This is known as ocular toxoplasmosis.</p>
<p>Contrary to much that is written about ocular toxoplasmosis, medical research shows this condition usually <a href="https://pubmed.ncbi.nlm.nih.gov/16226526/">affects healthy adults</a>. However, in aged persons or people with a weakened immune system, or when contracted during pregnancy, it can be more severe.</p>
<p>An attack of active inflammation causes “floaters” and blurred vision. When the inflammation progresses to scarring, there may be permanent loss of vision. </p>
<p>In a <a href="https://www.nature.com/articles/s41598-021-82830-z">study</a> of patients with ocular toxoplasmosis seen at a large ophthalmology clinic, we measured reduced vision to below driving level in more than 50% of eyes, and 25% of eyes were irreversibly blind.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/462169/original/file-20220510-17-mu0okv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="close up of person's eye" src="https://images.theconversation.com/files/462169/original/file-20220510-17-mu0okv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/462169/original/file-20220510-17-mu0okv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/462169/original/file-20220510-17-mu0okv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/462169/original/file-20220510-17-mu0okv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/462169/original/file-20220510-17-mu0okv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/462169/original/file-20220510-17-mu0okv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/462169/original/file-20220510-17-mu0okv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Toxoplasma</em> really likes the retina at the back of the eye and can leave a scar.</span>
<span class="attribution"><a class="source" href="https://images.unsplash.com/flagged/photo-1552065172-4f7d73c31fca?ixlib=rb-1.2.1&ixid=MnwxMjA3fDB8MHxzZWFyY2h8MTB8fHJldGluYSUyMGV5ZXxlbnwwfHwwfHw%3D&auto=format&fit=crop&w=800&q=60">Unsplash/Marc Schulte</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>How many eyes?</h2>
<p>Ophthalmologists and optometrists are quite familiar with managing ocular toxoplasmosis. But the extent of the problem is not widely recognised, even by the medical community. The number of Australians with ocular toxoplasmosis had never been measured, until now.</p>
<p>We wanted to investigate the prevalence of ocular toxoplasmosis in Australia, but we knew it would be challenging to get funding for a major survey of this neglected disease. So, we used information collected for a different purpose: as part of the Busselton Healthy Ageing Study, retinal photographs were taken from more than 5,000 baby boomers (born 1946–64) living in Busselton, Western Australia. The photographs <a href="https://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-13-936">were gathered</a> to look for other eye diseases, macular degeneration and glaucoma.</p>
<p>By screening these retinal photographs, we <a href="https://www.ophthalmologyretina.org/article/S2468-6530(22)00215-9/fulltext">estimated</a> the prevalence of ocular toxoplasmosis at one in 150 Australians. This might seem surprisingly common, but it fits with the way people catch <em>Toxoplasma</em>. </p>
<p>In addition to pet cats, Australia has huge populations of <a href="https://pubmed.ncbi.nlm.nih.gov/32547918/">feral cats</a>. And Australia is home to a lot of farmland, including over 50% of the <a href="https://www.researchgate.net/publication/329231876_Maps_of_Organic_Agriculture_in_Australia">global organic farming area</a>. </p>
<p>Most importantly, many Australians like to eat their <a href="https://bright-r.com.au/how-most-australians-prefer-their-steak-cooked/#:%7E:text=Research%20conducted%20by%20Brighter%20has,Australians%20prefer%20a%20medium%20steak.">red meat rare</a>, putting them at real risk. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/462171/original/file-20220510-24-li5uy5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="cute cat rolls on back" src="https://images.theconversation.com/files/462171/original/file-20220510-24-li5uy5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/462171/original/file-20220510-24-li5uy5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/462171/original/file-20220510-24-li5uy5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/462171/original/file-20220510-24-li5uy5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/462171/original/file-20220510-24-li5uy5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/462171/original/file-20220510-24-li5uy5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/462171/original/file-20220510-24-li5uy5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Yes, cats do spread <em>Toxoplasma</em>. But they’re not solely to blame.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/46TvM-BVrRI">Unsplash/Daria Shatova</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ive-always-wondered-can-i-flush-cat-poo-down-the-toilet-159340">I've always wondered: can I flush cat poo down the toilet?</a>
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</em>
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<h2>How the condition is treated</h2>
<p>To diagnose ocular toxoplasmosis, a retina examination is necessary, ideally with the pupils dilated. </p>
<p>The retinal lesion is easy to spot, because of the way <em>Toxoplasma</em> <a href="https://pubmed.ncbi.nlm.nih.gov/31569536/">activates retinal cells</a> to produce certain proteins, and an ophthalmologist or optometrist can immediately recognise the appearance. Often a blood test is also performed to make the diagnosis.</p>
<p>If the condition is mild, the doctor may let the body’s own immune system control the problem, which takes a few months. However, <a href="https://pubmed.ncbi.nlm.nih.gov/35197262/">usually</a> a combination of anti-inflammatory and anti-parasitic drugs is prescribed. </p>
<h2>Stopping the spread</h2>
<p><em>Toxoplasma</em> infection is not curable, but it can be prevented. Meat sold in Australian supermarkets <a href="https://pubmed.ncbi.nlm.nih.gov/31825558/">may harbour</a> <em>Toxoplasma</em>__. Cooking meat to an internal temperature of <a href="https://www.cdc.gov/parasites/toxoplasmosis/prevent.html">66°C</a> or freezing it ahead of cooking are ways to <a href="https://www.taylorfrancis.com/books/mono/10.1201/9781420092370/toxoplasmosis-animals-humans-dubey">kill the parasite</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/462177/original/file-20220510-15-xpot89.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="raw steak on a plate" src="https://images.theconversation.com/files/462177/original/file-20220510-15-xpot89.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/462177/original/file-20220510-15-xpot89.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=359&fit=crop&dpr=1 600w, https://images.theconversation.com/files/462177/original/file-20220510-15-xpot89.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=359&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/462177/original/file-20220510-15-xpot89.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=359&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/462177/original/file-20220510-15-xpot89.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=451&fit=crop&dpr=1 754w, https://images.theconversation.com/files/462177/original/file-20220510-15-xpot89.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=451&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/462177/original/file-20220510-15-xpot89.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=451&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Meat needs to be well-cooked to 66°C to kill the parasite.</span>
<span class="attribution"><a class="source" href="https://images.unsplash.com/photo-1638294133684-b2036f3ecd76?ixlib=rb-1.2.1&ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&auto=format&fit=crop&w=3371&q=80">Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Fresh fruit and vegetables should be washed before eating, and drinking untreated water (such as straight from rivers or creeks) should be avoided. Gloves should be worn when changing cat litter, and hands washed afterwards.</p>
<p>The World Health Organization and other international and national health bodies are promoting an approach called <a href="https://www.who.int/news-room/questions-and-answers/item/one-health">One Health</a> for diseases that cross humans, animals and their environments. This involves different sectors working together to promote good health. Now we know just how common ocular toxoplasmosis is in Australia, there is real justification to harness One Health to combat <em>Toxoplasma</em> infections in this country.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-dangerous-parasite-could-be-used-to-treat-cancer-new-research-in-mice-171022">A dangerous parasite could be used to treat cancer – new research in mice</a>
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<img src="https://counter.theconversation.com/content/182418/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Justine R. Smith receives funding from NHMRC, Macular Disease Foundation Australia, Australian Department of Industry, Science, Energy and Resources, Flinders Foundation, QEI Foundation and South Bank Day Hospital.</span></em></p><p class="fine-print"><em><span>João M. Furtado does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>We looked at eye photos and found one in every 150 Australians might have scarring from a common parasitic disease.Justine R. Smith, Professor of Eye & Vision Health, Flinders UniversityJoão M. Furtado, Associate Professor of Ophthalmology, Universidade de São Paulo (USP)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1828142022-05-11T12:05:04Z2022-05-11T12:05:04ZBeyond honey: 4 essential reads about bees<figure><img src="https://images.theconversation.com/files/462307/original/file-20220510-12-bnz0cm.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2330%2C1681&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Bumblebees at work, dotted with pollen.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/cFk2Cm">Crabchick/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>As spring gardening kicks into high gear, bees emerge from hibernation and start moving from flower to flower. These hardworking insects play an essential role <a href="https://www.fs.fed.us/wildflowers/pollinators/animals/bees.shtml">pollinating plants</a>, but they’re also interesting for many other reasons. Scientists study bees to learn about their intricate social networks, learning patterns and adaptive behaviors. These four stories from The Conversation’s archive offer diverse views of life in the hive.</p>
<h2>1. Females are the future</h2>
<p>The survival of bee colonies <a href="https://theconversation.com/spring-signals-female-bees-to-lay-the-next-generation-of-pollinators-134852">depends on female bees</a>, although they play different roles depending on their species. In social bee species, females find nesting spots to establish new colonies and lay hundreds of eggs there. </p>
<p>Other species are solitary, meaning that each bee lives alone. Females create segmented nests, lay an egg in each segment, deposit a ball of pollen to feed the larva, and then die off. </p>
<p>Female bees need support, especially early in the year when foraging options are few, doctoral student <a href="https://www.researchgate.net/profile/Lila-Westreich">Lila Westreich</a> notes. “It’s best to provide female bees with many early spring flowers – they rely on nectar from flowers to fuel their search for a nesting spot. Planting early-flowering plants such as willow, poplar, cherry trees and other spring blooms provides nectar for queen bees,” she writes. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/spring-signals-female-bees-to-lay-the-next-generation-of-pollinators-134852">Spring signals female bees to lay the next generation of pollinators</a>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/vf8QyIF3eoY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">In solitary bee species, females play the roles of queen and worker.</span></figcaption>
</figure>
<h2>2. Some bees are curious, others are focused</h2>
<p>All bees forage, but they do it in different ways. Some become very focused on the smell, colors and locations of known food sources and return to those flowers over and over. Others are more willing to explore and will change their behavior when they learn about new food sources. </p>
<p>As part of an experiment, Marquette University biologist <a href="https://scholar.google.com/citations?user=lGDvqJ8AAAAJ&hl=en">Chelsea Cook</a> and her colleagues bred populations of bees that were genetically programmed to be <a href="https://theconversation.com/some-bees-are-born-curious-while-others-are-more-single-minded-new-research-hints-at-how-the-hive-picks-which-flowers-to-feast-on-144900">either curious or focused</a>, and a colony that mixed these two styles together. Then they offered the bees a familiar food source and novel sources. Sure enough, the focused colony concentrated on the familiar source and the curious colony visited both known and novel sources. </p>
<p>In the mixed colony, bees came to concentrate more on the familiar source than the new ones over time. Why? The researchers observed how the bees communicated through their “waggle dance,” which tells nestmates where to find food, and saw that the focused bees were dancing faster. This conveyed their message more intensely than signals from slower dancers.</p>
<p>“Because curious bees are interested in everything, including new information about possible food locations, they are perfect listeners and are easily convinced to visit the chosen feeder of their enthusiastic nestmates,” Cook observes.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/some-bees-are-born-curious-while-others-are-more-single-minded-new-research-hints-at-how-the-hive-picks-which-flowers-to-feast-on-144900">Some bees are born curious while others are more single-minded – new research hints at how the hive picks which flowers to feast on</a>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/12Q8FfyLLso?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A scientist breaks down bees’ waggle dance.</span></figcaption>
</figure>
<h2>3. It takes a colony</h2>
<p>Bees communicate with one another about <a href="https://theconversation.com/honey-bees-cant-practice-social-distancing-so-they-stay-healthy-in-close-quarters-by-working-together-141106">many things besides food</a>. For example, bees use dancing to persuade their colony to move to a new nest site, write Providence College biologist <a href="https://scholar.google.com/citations?user=B6WmgvLL8vMC&hl=en">Rachael Bonoan</a> and Tufts University biologist <a href="https://scholar.google.com/citations?user=KF4sBDIAAAAJ&hl=en">Phil Starks</a>.</p>
<p>And bees work together to defend their colonies against external threats. Bonoan and Starks analyzed how honeybee colonies of varying sizes protected themselves against a fungus that causes a bee disease called chalkbrood. To do this, the researchers infected the colonies with the fungus and tracked the bees’ responses with thermal imaging.</p>
<p>The pathogen needs cool temperatures to infect bees, so the bees respond with heat. “When this pathogen is detected, worker bees protect the vulnerable young by contracting their large flight muscles to generate heat. This raises the temperature in the brood comb area of the hive just enough to kill the pathogen,” the biologists explain. Worker bees also remove diseased and dead young from the colony, which reduces the chance of infection spreading.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/honey-bees-cant-practice-social-distancing-so-they-stay-healthy-in-close-quarters-by-working-together-141106">Honey bees can't practice social distancing, so they stay healthy in close quarters by working together</a>
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<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1395430362315067396"}"></div></p>
<h2>4. Straining for the good of the swarm</h2>
<p>Computer scientist <a href="https://scholar.google.com/citations?user=xH5Ryy4AAAAJ&hl=en">Orit Peleg</a> at the University of Colorado Boulder studied yet another way in which bees work together for the good of the group. Peleg and her colleagues analyzed swarms that European honeybees form when a colony becomes so large that it’s about to split into two new groups. The relocating group forms a swarm that can hang from objects such as tree branches, and can change its shape, with each bee essentially holding hands with others next to it.</p>
<p>The scientists used a motor to shake a wooden board with a swarm of 10,000 honeybees hanging from the underside. By seeing how the swarm <a href="https://theconversation.com/what-a-bundle-of-buzzing-bees-can-teach-engineers-about-robotic-materials-125194">responded to shaking in various directions</a>, they hoped to gain insights that could inform the creation of adaptive structures made up of robots linked together. </p>
<p>“Using a computational model, we showed that bonds between bees located closer to where the swarm attaches to the board stretch more than bonds between bees at the far tip of the swarm,” Peleg recounts. “Bees could sense these different amounts of stretching, and use them as a directional signal to move upwards and make the swarm spread.”</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/462309/original/file-20220510-16-hqlk80.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A football-shaped cluster of bees hangs from a branch." src="https://images.theconversation.com/files/462309/original/file-20220510-16-hqlk80.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/462309/original/file-20220510-16-hqlk80.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=806&fit=crop&dpr=1 600w, https://images.theconversation.com/files/462309/original/file-20220510-16-hqlk80.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=806&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/462309/original/file-20220510-16-hqlk80.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=806&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/462309/original/file-20220510-16-hqlk80.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1013&fit=crop&dpr=1 754w, https://images.theconversation.com/files/462309/original/file-20220510-16-hqlk80.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1013&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/462309/original/file-20220510-16-hqlk80.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1013&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Bee swarm on a tree branch in Arkansas.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Swarming_(honey_bee)#/media/File:Bee_Swarm.JPG">Mark Osgathard/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>Put another way, the bees moved from locations where bonds stretched less to locations where they stretched more. “This behavioral response improves the collective stability of the swarm as a whole at the expense of increasing the average burden experienced by the individual bee,” Peleg concludes. </p>
<p>They found that when they shook the board horizontally, the swarm spread out into a wider, more stable cone. But it was less able to react to vertical shaking and eventually broke apart. That’s because vertical shaking didn’t disrupt the bonds between individual bees as much as horizontal shaking, so the swarm didn’t respond to vertical shaking by changing its shape.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-a-bundle-of-buzzing-bees-can-teach-engineers-about-robotic-materials-125194">What a bundle of buzzing bees can teach engineers about robotic materials</a>
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</em>
</p>
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<p><em>Editor’s note: This story is a roundup of articles from The Conversation’s archive.</em></p><img src="https://counter.theconversation.com/content/182814/count.gif" alt="The Conversation" width="1" height="1" />
Bees offer insights into many scientific questions, from cooperating in close quarters to strategies for finding food.Jennifer Weeks, Senior Environment + Cities Editor, The ConversationLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1780272022-02-28T11:05:55Z2022-02-28T11:05:55ZDon’t go wading in flood water if you can help it. It’s a health risk for humans – and dogs too<p>Floods are devastating communities in southeast Queensland and northern New South Wales and have pushed emergency services to their limits. </p>
<p>Flood waters in Northern NSW are already at “<a href="https://www.theguardian.com/environment/2022/feb/28/eastern-australian-states-hit-by-major-flooding-after-rain-bomb-weather-event">unprecedented</a>” levels, and are expected to worsen in coming days. The Australian Defence Force has been deployed to assist with emergency rescues.</p>
<p>In southeast Queensland, floods have <a href="https://www.theguardian.com/australia-news/2022/feb/28/brisbane-flood-2022-bne-river-peak-floods-update-property-flooding-warning-queensland">claimed eight lives</a>, after the equivalent of a year of rainfall fell in a couple of days. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1498106535859605504"}"></div></p>
<p>Some people who are flooded in won’t have the option of avoiding contact with flood water and mud. If this is you, try to wear protective clothing like closed-in shoes or boots and gloves. </p>
<p>Try keep cuts or abrasions away from dirty water, and disinfect and cover any wounds you might have with <a href="https://www.health.qld.gov.au/darlingdowns/healthier-together/healthiertogether-blog/flood-safety">waterproof dressings</a>. Focus on washing your hands with soap afterwards. </p>
<p>But if you’re tempted to wade into flood waters for fun, don’t. It not only risks your immediate safety, it poses a number of health hazards for humans – and dogs aren’t immune.</p>
<p>Health risks from flood water include bacteria and parasites that cause gastroenteritis (gastro), bacteria that infect the skin, physical hazards causing injury, and specific disease-causing pathogens that thrive in mud and water. </p>
<h2>Gastroenteritis</h2>
<p>Many of the organisms (viruses, bacteria and parasites) that cause gastro in humans happily survive for long periods of time in unchlorinated water. </p>
<p>These organisms originate in human faeces (poo) which can leak into drinking water when flood water inundates or damages septic tanks or sewerage pipes. If this occurs, people will be directed to boil their drinking water before use, a so-called “boil water” alert. </p>
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Read more:
<a href="https://theconversation.com/drinking-water-can-be-a-dangerous-cocktail-for-people-in-flood-areas-178028">Drinking water can be a dangerous cocktail for people in flood areas</a>
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<p>Pathogens that cause gastro need to be swallowed, so it’s less likely people will be exposed while walking in water. </p>
<p>But people can easily contaminate food and drinks if they don’t wash their hands thoroughly after contact with flood water. And those who play “flood water sports”, where they are likely to swallow water, are also at risk. </p>
<p>The most common symptoms of gastro are vomiting, diarrhoea and stomach cramps that begin six to 72 hours after infection. It’s usually not possible to tell which microbe has caused the infection without a laboratory test of the person’s stool. So if you have severe symptoms that aren’t getting better, see your GP. </p>
<p>Globally, floods and storms are <a href="https://doi.org/10.1017/s1049023x17006574">associated with increases in gastroenteritis</a>. However, case numbers of gastroenteritis <a href="https://doi-org.ezproxy.library.uq.edu.au/10.1016/S0031-3025(16)32706-4">didn’t increase after the 2011 floods in Queensland</a>.</p>
<h2>Leptospirosis</h2>
<p>Leptospirosis is a potentially life-threatening disease <a href="https://doi.org/10.1371/journal.pntd.0003843">associated with flooding</a> worldwide. It’s caused by infection with bacteria (<em>Leprospira</em>) that <a href="https://www.health.qld.gov.au/cdcg/index/lepto">enter the body</a> through broken skin (wounds) or our mucous membranes (lining of the eyes and mouth).</p>
<p>The bacteria are present throughout the world and <a href="https://doi.org/10.1371/journal.pone.0227055">can survive</a> in mud and soil for weeks if it’s moist and warm. </p>
<p>In urban areas, rats and mice are the main <a href="https://www.health.nsw.gov.au/Infectious/factsheets/Pages/leptospirosis.aspx">carriers</a> of <em>Leptospira</em> and in rural areas, cattle add a further source. </p>
<p><em>Leptospira</em> are washed from soil into flood water with rain, which means anyone walking in water can become infected through cuts and abrasions.</p>
<p>Of particular concern is when the water recedes and the clean-up period begins because the contact with mud is much greater, as is the risk of wounds.</p>
<p>Leptospirosis <a href="https://www.health.nsw.gov.au/Infectious/factsheets/Pages/leptospirosis.aspx">causes</a> a fever and flu-like symptoms initially, and requires prompt diagnosis via a blood test and treatment with antibiotics. Anyone with a prolonged fever who has had contact with mud and flood water should see their GP. </p>
<p>After the floods in 2011, Queensland reported a nearly <a href="https://www1.health.gov.au/internet/main/publishing.nsf/Content/cda-cdi3901-pdf-cnt.htm/$FILE/cdi3901g.pdf">65% increase in the number of cases of leptospirosis</a>, most of which occurred in the weeks after the floods. </p>
<h2>The risk extends to our canine friends</h2>
<p>Leptospirosis is also a risk for suburban dogs and <a href="https://doi.org/10.1111/avj.13148">can be fatal</a>. </p>
<p>While there are no reports of cases of dog leptospirosis associated with floods in Australia, the <a href="https://doi.org/10.1111/avj.13148">emergence of the disease</a> in dogs in Sydney has raised concerns among veterinarians because they don’t understand why it suddenly became a problem. </p>
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<img alt="Dog plays in mud" src="https://images.theconversation.com/files/448875/original/file-20220228-25-10fsn66.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/448875/original/file-20220228-25-10fsn66.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/448875/original/file-20220228-25-10fsn66.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/448875/original/file-20220228-25-10fsn66.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/448875/original/file-20220228-25-10fsn66.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/448875/original/file-20220228-25-10fsn66.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/448875/original/file-20220228-25-10fsn66.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Try to keep your dog away from the mud after a flood.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/golden-retriever-cooling-down-mud-puddle-400343500">Shutterstock</a></span>
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<p>The best advice is to keep the dogs out of flood waters. If you observe listlessness, vomiting and lack of appetite in your dog one to two weeks after exposure to mud or flood water, take them to the vet immediately. </p>
<p>It can be diagnosed with a blood test and treated with antibiotics, in much the same way as for people.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-is-leptospirosis-and-how-can-it-harm-us-and-our-pets-120221">Explainer: what is leptospirosis and how can it harm us and our pets?</a>
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<h2>Injuries and skin infections</h2>
<p>A <a href="https://doi.org/10.1016/S0031-3025(16)32706-4">common health condition after the 2011 floods in Queensland</a> was cellulitis, a deep bacterial infection of the skin that can occur if a person gets a puncture wound.</p>
<p>Many types of bacteria <a href="https://www.hopkinsmedicine.org/health/conditions-and-diseases/cellulitis#:%7E:text=Cellulitis%20is%20a%20deep%20infection,break%2C%20including%20trauma%20or%20surgery.">can infect a wound</a> including those normally on human skin such as <em>Staphylococcus aureus</em> (golden staph) and those from the environment, such as <em><a href="https://doi.org/10.1016/S0031-3025(16)32705-2">Aeromonas</a></em>. </p>
<p>The symptoms include an area of skin that is red, painful, swollen, and warm to touch. If someone with these symptoms develops a fever, chills and nausea, it’s important they get medical attention to ensure they don’t develop a bloodstream infection. </p>
<p>Cellulitis is usually treated at home using antibiotics. </p>
<p>When cleaning up after floods, try to avoid getting wounds by using protective equipment, because even minor wounds <a href="https://www.abc.net.au/news/2011-01-15/rudd-treated-for-infection-from-floodwater/1906022">are entry points</a> for bacteria. </p>
<p>If you do sustain skin wounds, quickly clean and disinfect them, and seek medical attention, as you may need a <a href="https://www.healthdirect.gov.au/tetanus">tetanus vaccination</a>. Tetanus is a rare, but fatal, condition in Australia because of widespread vaccination. But it’s important to maintain immunity to tetanus through regular boosters.</p>
<p>Seek medical care if you develop <a href="https://www.publications.qld.gov.au/dataset/public-health-disaster-management-fact-sheets/resource/fb0f503c-67a6-4b15-8a22-783660ee4eab">any infections</a> after exposure to mud or flood water.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/heres-what-you-need-to-know-about-melioidosis-the-deadly-infection-that-can-spread-after-floods-111813">Here's what you need to know about melioidosis, the deadly infection that can spread after floods</a>
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<img src="https://counter.theconversation.com/content/178027/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Simon Reid does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>If you’re tempted to wade into flood waters for fun, don’t. It not only risks your immediate safety, it’s also a threat to your health.Simon Reid, Associate Professor, Communicable Disease Control, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1764812022-02-08T14:11:46Z2022-02-08T14:11:46ZState capture in South Africa: how the rot set in and how the project was rumbled<figure><img src="https://images.theconversation.com/files/445112/original/file-20220208-12-13qr8a6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Ajay Gupta, left, and Atul Gupta, the masterminds behind state capture in South Africa.</span> <span class="attribution"><span class="source">Muntu Vilakazi/City Press</span></span></figcaption></figure><p>It seems the time of reckoning for the massive corruption that has hobbled South Africa’s economy is nigh. Two parts of the three-part report by the judicial commission investigating allegations of <a href="https://www.statecapture.org.za/">state capture</a> under former President Jacob Zuma have now been published. The third is due at the end of February. </p>
<p><a href="https://www.researchgate.net/publication/325777788_Theoretical_analysis_of_state_capture_and_its_manifestation_as_a_governance_problem_in_South_Africa">“State capture”</a> has become the South African term for what is elsewhere called kleptocracy. </p>
<p>Here I reflect on <a href="https://www.thepresidency.gov.za/documents">Part 2</a> of the report.</p>
<p>Ideally, a review of the complex Zondo Commission Report Part 2 requires a team of three co-authors: a chartered accountant, a political scientist, and a jurist specialising in company law. This review cannot do justice to a summary of a report when part 2 alone exceeds 640 pages. Instead, I will focus on some thoughts and analysis.</p>
<p>These opening observations are drawn from my knowledge of politics, informed by what’s in the report.</p>
<p>Firstly, the <a href="https://www.bbc.com/news/world-africa-22513410">Gupta family</a> – friends of former President Jacob Zuma’s who, the commission says, orchestrated massive corruption and the capture of the South African state with Zuma’s help – were rumbled by events that caught them off-guard.</p>
<p>They had not, for example, anticipated that their actions in South Africa would result in a media uproar and political backlash. The media’s role in the ultimate demise is recognised in this latest report. The commission praises <a href="https://shadowworldinvestigations.org/">Shadow World Investigation </a> (Zondo,pp.19, 229); <a href="https://amabhungane.org/">AmaBhungane</a> (Zondo, p.260); <a href="https://mg.co.za/">Mail and Guardian </a>; and <a href="https://www.opensecrets.org.za/">Open Secrets</a>, (Zondo,p.261); for investigative exposés of state capture. </p>
<p>These exposes eventually saw the Gupta’s <a href="https://www.timeslive.co.za/politics/2016-04-10-guptas-leave-south-africa/">fleeing to the United Arab Emirates</a> in 2016. </p>
<p>They also never anticipated that South African banks would <a href="https://businesstech.co.za/news/banking/272357/banks-tell-how-government-threatened-banking-licences-after-closing-gupta-accounts/#:%7E:text=Standard%20Bank%2C%20Nedbank%2C%20FNB%20and,the%20breaking%20state%20capture%20scandal">close down all their corporate and personal accounts</a>. This ultimately pressured the South African branch of India’s Bank of Baroda – their original home base – to reluctantly <a href="https://www.news24.com/fin24/breaking-bank-of-baroda-sa-closing-gupta-accounts-20170302">follow suit</a>.</p>
<p>These developments indicate that South Africa’s institutional safeguards, civil society NGOs, and democratic culture are more robust than those of some other countries.</p>
<p>The Guptas were also rumbled because they failed to take note of the fact that the most successful parasites never harm their hosts. That’s so they enjoy a lifelong nurturing host environment. The scale of their rapaciousness meant that, within just a few years, the institutions they leeched were in a state of collapse. These included <a href="https://www.transnet.net/Pages/Home.aspx">Transnet</a>, the transport parastatal, <a href="https://www.news24.com/fin24/companies/just-in-state-capture-inquiry-finds-saa-racked-by-corruption-and-fraud-under-dudu-myeni-20220104">South African Airways</a>, the national carrier, <a href="https://www.engineeringnews.co.za/article/corruption-watch-turns-focus-to-eskom-in-review-of-zondo-commission-report-2022-01-12">Eskom</a>, the power utility, <a href="http://www.denel.co.za/">Denel</a>, the state defence, security and related technology company.</p>
<p>Aspects of the report show how this happened. </p>
<h2>Zondo Commission report part 2</h2>
<p>The specifics of this part of the Zondo report are that procurement and related crimes cost Transnet, R41 billion (equivalent to US$2,7 billion), which amounts to 72% of all contracts tainted by corruption (p.19). </p>
<p>These losses mounted following successive decisions that were driven by avarice and corruption. One example was the decision over a new chief executive for Transnet. When <a href="https://www.news24.com/news24/southafrica/investigations/state-capture-report-zuma-should-be-investigated-for-transnet-corruption-20220202">Barbara Hogan</a>, then a cabinet minister in charge of the state transport company, resisted Zuma’s demands on who to appoint as chief executives, he <a href="https://www.polity.org.za/article/i-knew-i-was-going-to-be-dismissed-hogan-at-state-capture-inquiry-2018-11-14">fired her from the cabinet</a>, and sought to redeploy her as ambassador to Finland. </p>
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<img alt="A man wearing a tie and jacket holds a COVID-19 mask he is preparing to put on." src="https://images.theconversation.com/files/445065/original/file-20220208-17-1pyi0tc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/445065/original/file-20220208-17-1pyi0tc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=392&fit=crop&dpr=1 600w, https://images.theconversation.com/files/445065/original/file-20220208-17-1pyi0tc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=392&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/445065/original/file-20220208-17-1pyi0tc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=392&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/445065/original/file-20220208-17-1pyi0tc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=493&fit=crop&dpr=1 754w, https://images.theconversation.com/files/445065/original/file-20220208-17-1pyi0tc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=493&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/445065/original/file-20220208-17-1pyi0tc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=493&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Former Transnet CEO Siyabonga Gama testified at the State Capture Inquiry in April 2021.</span>
<span class="attribution"><span class="source">Photo: Luba Lesolle/Gallo Images via Getty Images</span></span>
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<p>The commission found that the man Zuma preferred, <a href="https://www.timeslive.co.za/sunday-times/news/politics/2022-02-06-zondo-is-trying-to-zumarise-me-says-former-transnet-ceo-siyabonga-gama/">Siyabonga Gama</a>, should be prosecuted for transactions involving the Guptas, amounting to billions.</p>
<p>There were other attempts at resistance too. Take the actions of Denel CEO Riaz Saloojee. He refused to take bribes. But his efforts came to nought. The Guptas, through Zuma’s new appointment <a href="https://www.news24.com/fin24/companies/denel-almost-on-its-knees-over-capture-supported-by-lynne-brown-dan-mantsha-20220201">Lynn Brown</a> to the portfolio of running state enterprises, simply suspended him and appointed a new board of directors that was more pliable to the Guptas.</p>
<p>Beyond detailing how appointments were made, the report focuses a great deal of analysis about highly technical banking techniques and financial transactions. These show how in every case the lowest bid tender, or the most cost-effective solution, was rejected, so as to provide openings for middlemen, Gupta-controlled companies, to profit.</p>
<h2>The fight back</h2>
<p>In the immortal words of one of Nigeria’s heroes against corruption, its former finance minister and current World Trade Organisation president, Ngozi Okonjo-Iweala:</p>
<blockquote>
<p><a href="https://mitpress.mit.edu/books/reforming-unreformable">when you fight corruption, corruption fights back</a>. </p>
</blockquote>
<p>Corruption is indeed fighting back. </p>
<p>As a result, it has become one major dimension of the factionalism now <a href="https://theconversation.com/factionalism-and-corruption-could-kill-the-anc-unless-it-kills-both-first-116924">wracking the ruling African National Congress (ANC)</a>. It is evidenced by pseudo-populist attacks on “<a href="https://theconversation.com/white-monopoly-capital-an-excuse-to-avoid-south-africas-real-problems-75143">white monopoly capital</a>”, the “<a href="https://blackopinion.co.za/2019/09/22/supra-attacked-by-stellenbosch-mafia-blf/">Stellenbosch mafia</a>”, and on <a href="https://ewn.co.za/2021/03/30/ramaphosa-distances-anc-from-zuma-attacks-on-judiciary-warns-ret-forces">President Cyril Ramaphosa</a>. </p>
<p>In US slang, this is not grassroots rhetoric, but an <a href="https://www.thoughtco.com/what-is-astroturfing-definition-and-examples-5082082">Astroturf campaign</a>, referring to a campaign pretending to be populist, but actually waged by a business clique of tenderers and their political clients. </p>
<p>They richly deserve the South African Communist Party witticism denouncing <a href="https://www.gov.za/tenderpreneurship-stuff-crooked-cadres-fighters">“tenderpreneurs”</a> – ‘businesspeople’ who enrich themselves through government tenders, often dubiously.</p>
<h2>Recommendations</h2>
<p>The Zondo Commission makes useful recommendations. </p>
<p>One is that in future, Cabinet ministers should not have unlimited power to appoint their cronies as chairs or board members to parastatals. Instead, all candidates for board members of state-owned enterprises should be subject to the background checks and procedures akin to those of the <a href="https://www.judiciary.org.za/index.php/judicial-service-commission/about-the-jsc">Judicial Service Commission</a>, which advises the government on any matters relating to the judiciary or administration of justice and adjudicates complaints brought against judges. </p>
<p>In turn the board members, not the minister, should elect their chairs and CEOs.</p>
<p>Zondo also points out that it is not yet a crime in itself to abuse public power for a politician’s private interest. This should be criminalised across the board, from the President down to the lowest official.</p>
<p>Finally, the success or failure of the Zondo Commission Report will be <a href="https://theconversation.com/state-capture-report-chronicles-extent-of-corruption-in-south-africa-but-will-action-follow-174441">what consequences will result from it </a> for the criminals and corrupt, <a href="https://theconversation.com/its-imperative-that-south-africa-moves-fast-on-state-capture-prosecutions-heres-why-174614">such as prosecutions</a>, and reclaiming illegal and illicit profits from tenderers. </p>
<p>South Africa has witnessed a decade of unimplemented recommendations of commission reports, from the <a href="https://www.researchgate.net/publication/285846781_The_Khayelitsha_Commission_of_Inquiry_Challenging_the_scope_of_provincial_policing_powers">Khayelitsha Commission</a>, appointed in December 2012 to investigate police inefficiency, to the <a href="https://justice.gov.za/comm-mrk/index.html">Farlam Commission</a> into the 2012 Marikana massacre.</p>
<p>It’s not known if the Zondo Commission reports will fare any better.</p>
<p>What’s clear, however, is that the number of successful prosecutions, and the amount of plundered funds retrieved, will be a key deterrence to future instances of corruption. Crucial here will be to what extent Treasury will increase the budget allotted to the <a href="https://www.npa.gov.za/">National Prosecution Authority</a>, the <a href="https://www.siu.org.za/">Special Investigative Unit</a>, and the <a href="https://www.npa.gov.za/asset-forfeiture-unit#:%7E:text=Empowered%20by%20the%20Prevention%20of,the%20private%20and%20public%20sector">Assets Forfeiture Unit</a>.</p>
<p>The country now awaits the third part of the Zondo Commission report, due at the end of February.</p><img src="https://counter.theconversation.com/content/176481/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Keith Gottschalk is an ANC member, but writes this review in his professional capacity as a political scientist.</span></em></p>The scale of the Guptas’ rapaciousness meant that, within just a few years, the institutions they leeched were in a state of collapse.Keith Gottschalk, Political Scientist, University of the Western CapeLicensed as Creative Commons – attribution, no derivatives.