tag:theconversation.com,2011:/us/topics/vector-borne-diseases-9943/articlesVector-borne diseases – The Conversation2023-09-21T21:27:36Ztag:theconversation.com,2011:article/2085382023-09-21T21:27:36Z2023-09-21T21:27:36ZLyme disease: The pathogen’s cunning strategies for persistent infection offer clues for vaccine development<figure><img src="https://images.theconversation.com/files/547386/original/file-20230911-25-n5os9t.JPG?ixlib=rb-1.1.0&rect=65%2C23%2C1709%2C1158&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The black-legged tick is the vector that spreads Lyme disease. Its bite can infect humans with the Borrelia burgdorferi bacterium.</span> <span class="attribution"><span class="source">(Jim Gathany/CDC)</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/lyme-disease-the-pathogens-cunning-strategies-for-persistent-infection-offer-clues-for-vaccine-development" width="100%" height="400"></iframe>
<p>Lyme disease is the leading <a href="https://www.who.int/news-room/fact-sheets/detail/vector-borne-diseases">vector-borne disease</a> — meaning diseases that are transmitted to humans from another organism like a tick or mosquito — in <a href="https://doi.org/10.1186/s12889-019-7069-6">North America and Europe</a>. </p>
<p><a href="https://doi.org/10.3201/eid2702.202731">New human cases are estimated</a> at over <a href="http://dx.doi.org/10.15585/mmwr.ss6622a1">400,000 in the United States each year</a>. Canada has experienced a drastic increase in human cases, <a href="https://www.canada.ca/en/public-health/services/diseases/lyme-disease/surveillance-lyme-disease.html#a5">from 266 cases in 2011 to 3,147 in 2021</a>, as the habitat of its vector, a tick, expands north. </p>
<p>The initial symptoms of human Lyme disease can be vague, such as fever, headache, fatigue and often rash. It is a potentially serious condition that can affect multiple systems in the body — including the heart, nervous system and joints — and can become a chronic illness.</p>
<p>Lyme disease is caused by a unique, spiral-shaped (spirochete) bacterium called <a href="https://doi.org/10.1099/00207713-34-4-496"><em>Borrelia burgdorferi</em></a>. <em>B. burgdorferi</em> cannot survive in the environment on its own. For <a href="https://doi.org/10.21775/cimb.042.473">survival and transmission</a>, it requires susceptible hosts (usually small mammals or birds) and a <a href="https://doi.org/10.1056/NEJM198303313081301">specific vector</a>: the black-legged tick, also called the deer tick.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/535388/original/file-20230703-257464-m0lz6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/535388/original/file-20230703-257464-m0lz6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=420&fit=crop&dpr=1 600w, https://images.theconversation.com/files/535388/original/file-20230703-257464-m0lz6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=420&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/535388/original/file-20230703-257464-m0lz6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=420&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/535388/original/file-20230703-257464-m0lz6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=528&fit=crop&dpr=1 754w, https://images.theconversation.com/files/535388/original/file-20230703-257464-m0lz6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=528&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/535388/original/file-20230703-257464-m0lz6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=528&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Lyme disease infectious cycle: Adult ticks lay egg sacs that can hatch thousands of tick larvae. Larvae are not born with Borrelia burgdorferi but can acquire the bacterium when they feed on an infected host. After feeding, larvae molt to nymphs which must feed once to molt to adults. Female adult ticks also feed once before laying the egg sac. Nymphs and adult ticks can transmit B. burgdorferi to susceptible hosts while feeding.</span>
<span class="attribution"><span class="source">(BioRender)</span></span>
</figcaption>
</figure>
<h2>Evading the immune system</h2>
<p><em>B. burgdorferi</em> must survive extremely diverse conditions over the course of its transmission and infection cycle: from host to tick vector, and then into new hosts. </p>
<p>This bacterium senses and responds to its surroundings, most notably by <a href="https://doi.org/10.1128/iai.70.7.3382-3388.2002">modifying its appearance</a> by changing the <a href="https://doi.org/10.1073/pnas.92.7.2909" title="). _B. burgdorferi_ has over [50 surface-exposed proteins](https://doi.org/10.1128/jb.00658-16 "">proteins on its outer surface</a> to <a href="https://doi.org/10.1111/j.1574-695X.2012.00980.x">help it survive</a> in either <a href="https://doi.org/10.1038/s41467-023-35897-3">the tick</a> or the host.</p>
<p>When a tick infected by <em>B. burgdorferi</em> bites and feeds on a vertebrate host, it provides a signal for the bacteria to switch its proteins to those required to infect the host, and to begin migrating through the tick and into the bite site. This process takes between <a href="https://doi.org/10.4269/ajtmh.1995.53.397">36 and 72 hours</a>. </p>
<p>However, many of these proteins are recognized by the host as foreign, and the host’s immune system works to try to clear the infection. This includes a strong, antibody response targeted against <em>B. burgdorferi</em>. </p>
<p>Despite these immune responses, <em>B. burgdorferi</em> is able to cause long-term infections. In natural host reservoirs — the animals that the bacterium usually finds itself in via tick bites, such as small rodents — these infections do not cause diseases like those seen in humans and other <a href="https://doi.org/10.1016/j.idc.2007.12.013">non-natural reservoirs</a>. </p>
<p>In fact, the bacteria itself does not produce any products that would be <a href="https://doi.org/10.1016/j.cll.2015.07.004">toxic to its hosts</a>, either natural or non-natural. Yet chronic infection in humans can lead to <a href="https://doi.org/10.1038/nrdp.2016.90">Lyme neuroborreliosis, carditis and Lyme arthritis</a>.</p>
<figure class="align-center ">
<img alt="Bacteria that look like bright green and yellow squiggles against a dark green background" src="https://images.theconversation.com/files/548570/original/file-20230915-23-4ysjok.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/548570/original/file-20230915-23-4ysjok.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=612&fit=crop&dpr=1 600w, https://images.theconversation.com/files/548570/original/file-20230915-23-4ysjok.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=612&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/548570/original/file-20230915-23-4ysjok.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=612&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/548570/original/file-20230915-23-4ysjok.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=770&fit=crop&dpr=1 754w, https://images.theconversation.com/files/548570/original/file-20230915-23-4ysjok.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=770&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/548570/original/file-20230915-23-4ysjok.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=770&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Microscopic image of Lyme disease bacteria Borrelia burgdorferi. In this photo, immunofluorescent antibodies have been used to change the colour of spirochetes that express different outer surface proteins.</span>
<span class="attribution"><span class="source">(NIAID)</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>How then, are these bacteria able to cause such a devastating disease in humans and other animals, but not in their natural host reservoirs?</p>
<p>While there is still much to learn about <em>B. burgdorferi</em>, we know of several factors that play a role in the <a href="https://doi.org/10.1038/nrdp.2016.90">range of disease it causes</a>. These include:</p>
<ul>
<li>its genetic make-up, </li>
<li>its ability to access various tissues (such as the joints, heart and nervous system) due to its <a href="https://doi.org/10.1128/iai.01228-12">ability to move around (motility)</a>, and </li>
<li>the immune response of the host. </li>
</ul>
<p>Apart from motility, <em>B. burgdorferi</em> also protects itself from the strong <em>B. burgdorferi</em>-specific targeted antibody response of its host’s immune system by changing the appearance of the main outer surface protein expressed during persistent infection in a process called <a href="https://doi.org/10.1128/iai.66.8.3698-3704.1998">antigenic variation</a>.</p>
<h2>How Lyme disease is perpetuated</h2>
<p>In addition to antigenic variation, <em>B. burgdorferi</em> bacteria can also change their DNA by <a href="https://doi.org/10.1073/pnas.0402745101">exchanging genetic information, a process also known as gene transfer</a>. This process allows these bacteria to further alter their <a href="https://doi.org/10.1128/mbio.00153-10">appearance</a> <a href="https://doi.org/10.1534/genetics.111.130773">during infection</a> to avoid the host immune system.</p>
<p>This process works so well that these <em>B. burgdorferi</em> bacteria appear different enough to allow <a href="https://doi.org/10.7326/0003-4819-127-2-199707150-00006">re-infection</a> or even <a href="https://doi.org/10.1128/iai.01817-14">co-infection</a> (where multiple strains of B. burgdorferi infect a single host at the same time) of a vertebrate host, like a mouse or a human, despite the presence of specific antibodies to fight the bacterium.</p>
<p>In fact, in nature, the majority of host reservoirs and the ticks that carry the bacterium are infected with <a href="https://doi.org/10.1128/AEM.02296-15">multiple strains of <em>B. burgdorferi</em></a>. The ability of <em>B. burgdorferi</em> to reinfect and co-infect both ticks and hosts increases the spread of the bacteria in the environment as well as the chances that humans will encounter Lyme disease.</p>
<h2>Human cases of Lyme disease are increasing</h2>
<p>As a vector-borne pathogen, <em>B. burgdorferi</em> only infects individuals that are bitten by an infected tick. It is not transmitted from <a href="https://doi.org/10.1093/cid/ciz872">person to person</a>.</p>
<p>Environments that support black-legged/deer ticks are at risk of harbouring <em>B. burgdorferi</em>. In North America, these species of ticks are widely distributed throughout the eastern and midwestern United States. Recent <a href="https://doi.org/10.1093/jme/tjy104">geographic expansion</a> to the north is increasing the prevalence of Lyme disease <a href="https://doi.org/10.1503/cmaj.080148">in Canada</a>. </p>
<p>The increase of human Lyme disease cases highlights the failure of existing preventive strategies — such as minimizing exposure to tick habitats, performing diligent tick checks, and wearing suitable clothing when performing activities in known tick habitats — and emphasizes the need for an effective <a href="https://doi.org/10.21775/cimb.042.191">human vaccine</a>.</p>
<h2>A One Health approach</h2>
<p>At <a href="https://www.vido.org/">Vaccine and Infectious Disease Organization</a> at the University of Saskatchewan, we are taking a <a href="https://ipac-canada.org/one-health">One Health</a> approach by recognizing that human health is closely related to the health of animals and the shared environment. We are investigating the role of <em>B. burgdorferi</em>, ticks, and susceptible animals on the spread and survival of the Lyme disease bacterium. </p>
<p>It is important to mimic the natural infectious cycle as much as possible when identifying potential vaccine and drug targets. This is because the way host animals are infected (for example, artificial needle infection or natural tick bite) can produce drastic differences in the resulting infection. </p>
<p>Additionally, despite the prevalence of this disease, there are still many aspects of the infectious cycle that remain unknown due to the uniqueness of <em>B. burgdorferi</em> and a lack of knowledge about the tick vector. </p>
<p>For example, we recently learned that a <em>B. burgdorferi</em> protein is responsible for regulating the components necessary for the bacterium to infect vertebrates, including humans. The absence of this protein, among other things, leads to the <a href="https://doi.org/10.1038/s41467-023-35897-3">death of <em>B. burgdorferi</em> in ticks</a>, making it an exciting target for research investigation. </p>
<p>By learning more about the molecular mechanisms that change or reduce the severity of the disease caused by this bacterium, we can identify new targets for the prevention of human Lyme disease.</p><img src="https://counter.theconversation.com/content/208538/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jenny Wachter 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 bacterium that causes Lyme disease is a master of disguise, changing its appearance to evade the immune system as it moves from the ticks that carry it to humans or animals.Jenny Wachter, Research scientist/Adjunct professor, University of SaskatchewanLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2129552023-09-17T12:07:36Z2023-09-17T12:07:36ZWhat Canadians need to know about West Nile virus, a mosquito-borne infection that can be life-threatening<iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/what-canadians-need-to-know-about-west-nile-virus-a-mosquito-borne-infection-that-can-be-life-threatening" width="100%" height="400"></iframe>
<p>During the late summer of 1999, New York City recorded an <a href="https://doi.org/10.2105%2Fajph.92.8.1218">unusual number of cases of encephalitis</a> (inflammation of the brain). At the same time, the <a href="https://www.nationalgeographic.com/science/article/west-nile-virus-the-stranger-that-came-to-stay">Bronx Zoo</a> reported a massive death of birds and mammals. </p>
<p>The human encephalitis cases might have been attributed to a flare-up of an endemic arbovirus (<a href="https://ndc.services.cdc.gov/case-definitions/arboviral-diseases-neuroinvasive-and-non-neuroinvasive-2015/">a virus transmitted by a tick or mosquito bite</a>) such as <a href="https://www.cdc.gov/sle/index.html">St. Louis encephalitis</a>, but the concurrent bird and mammal deaths suggested the human illnesses warranted further investigation. </p>
<p>Scientists eventually identified these as the first confirmed cases of West Nile virus (WNV) in North America.</p>
<h2>West Nile virus in North America</h2>
<p>WNV was first reported in a woman with a fever in Uganda in 1937. An <a href="https://doi.org/10.2214/ajr.184.3.01840957">outbreak in Israel in 1957</a> established WNV as a cause of <a href="https://doi.org/10.3201/eid0704.017416">severe meningoencephalitis</a> (inflammation of the spinal cord and brain) in elderly patients. </p>
<p>Several clusters or medium-range outbreaks were reported from Asia, Europe and Africa in the 20th century. Finally, the virus managed to cross the Atlantic and landed in North America in 1999.</p>
<figure class="align-center ">
<img alt="Round blue particles nestled in a red matrix" src="https://images.theconversation.com/files/548213/original/file-20230914-19-x6rm98.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/548213/original/file-20230914-19-x6rm98.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=454&fit=crop&dpr=1 600w, https://images.theconversation.com/files/548213/original/file-20230914-19-x6rm98.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=454&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/548213/original/file-20230914-19-x6rm98.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=454&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/548213/original/file-20230914-19-x6rm98.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=570&fit=crop&dpr=1 754w, https://images.theconversation.com/files/548213/original/file-20230914-19-x6rm98.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=570&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/548213/original/file-20230914-19-x6rm98.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=570&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Microscopic view of West Nile virus particles in a cell.</span>
<span class="attribution"><span class="source">(NIAID)</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>In 1999, the <a href="https://www.cdc.gov/westnile/statsmaps/historic-data.html">case number</a> was limited to 62 in New York City, and there was concern about a huge surge in 2000. Fortunately, the case number in 2000 was 21, which is exceedingly low, but it had spread to New Jersey and Connecticut. The case number remained in a similar low range (only 66 cases) in 2001. </p>
<p>However, the virus hit hard the following year. In 2002, the case number rose to over 4,000 in the United States. The same year, <a href="https://www.canada.ca/en/public-health/services/diseases/west-nile-virus/surveillance-west-nile-virus.html">Canada experienced its first cases</a> in Ontario.</p>
<p>The U.S. has reported a <a href="https://www.cdc.gov/westnile/statsmaps/historic-data.html">cumulative total</a> of 56,569 cases and 2,773 deaths, while <a href="https://www.canada.ca/en/public-health/services/diseases/west-nile-virus/surveillance-west-nile-virus.html#a1">Canada has reported 6,683 cases</a> and about 150 deaths (I’m told by the Centre for Food-borne, Environmental & Zoonotic Infectious Diseases, Public Health Agency of Canada), with the highest number of cases observed in the U.S. in 2003 and in Canada in 2007.</p>
<p>This virus spread across the entire continent very quickly, and covered most of North America by 2005. However, it took almost 10 years for the virus to <a href="https://doi.org/10.1089/vbz.2010.0062">show up in British Columbia</a>. In Canada, most of the cases were found in the Prairie region (Alberta, Saskatchewan and Manitoba). <a href="https://www.cdc.gov/westnile/statsmaps/historic-data.html">In the U.S.</a>, Midwestern states have been most affected.</p>
<p>West Nile virus is an RNA virus, a close cousin of <a href="https://www.who.int/news-room/fact-sheets/detail/dengue-and-severe-dengue">Dengue</a>, <a href="http://www.bccdc.ca/health-info/diseases-conditions/yellow-fever">Yellow fever</a>, St. Louis encephalitis and <a href="http://www.bccdc.ca/health-info/diseases-conditions/zika-virus">Zika virus</a>, to name a few. It belongs to the family Flaviviridae. </p>
<h2>Symptoms and transmission</h2>
<p><a href="https://www.cdc.gov/westnile/symptoms/index.html">Approximately 80 per cent of people</a> exposed to WNV are asymptomatic. <a href="https://doi.org/10.14745/ccdr.v40i10a01">The incubation period</a> in humans is about a week; however, this ranges from two to 15 days after the virus enters the body.</p>
<p>Among symptomatic individuals, all of them experience fever, and many also experience headaches, body aches, a mild rash and swollen lymph glands to varying degrees. </p>
<p>Although most cases go unnoticed, the virus still has deadly potential. <a href="https://nccid.ca/debrief/west-nile-virus/">A small number of people</a> (around one per cent) experience severe symptoms, including encephalitis. However, over the years, the <a href="https://doi.org/10.1038/ncpneuro0176">number of neurological cases has been increasing</a>.</p>
<p>This virus is mostly <a href="https://www.who.int/news-room/fact-sheets/detail/west-nile-virus">transmitted via mosquito bites</a>; however, very rarely it could transmit via blood transfusion, organ or tissue transplants, from mother to unborn babies and through exposure to infected animals. </p>
<p>A number of birds, predominantly corvids such as crows, jays and magpies, act as reservoirs as well as <a href="https://www.biologyonline.com/dictionary/amplifier-host">amplifying hosts</a>. When an uninfected mosquito feeds on an infected bird and then bites a healthy human, the human becomes infected. </p>
<p>Humans are considered dead-end hosts, meaning that even if a mosquito feeds on an infected individual, that mosquito cannot transmit the virus to another individual <a href="https://www.who.int/news-room/questions-and-answers/item/dengue-and-severe-dengue">as can happen with the dengue virus</a>.</p>
<p>Once people are severely infected with West Nile virus, they <a href="https://www.cdc.gov/westnile/symptoms/index.html">acquire longer immunity</a>. Older people are usually at high risk for severe infection due to underlying health conditions. People with diabetes and uncontrolled hypertension <a href="https://www.canada.ca/en/public-health/services/diseases/west-nile-virus/risks-west-nile-virus.html">have a greater risk</a> of developing severe neurological disease from the West Nile virus. </p>
<h2>Diagnosis</h2>
<p>Patients who become ill with a fever and severe headache within a few days of a mosquito bite should visit their family physician or any health-care facility.</p>
<p>Because WNV is closely related to other pathogens, diagnosis is often challenging.
Patient signs and symptoms, history of mosquito bites and laboratory tests are all important when assessing patients for possible infection with West Nile virus.</p>
<p>The most common <a href="https://www.publichealthontario.ca/en/Laboratory-Services/Test-Information-Index/West-Nile-Virus-Serology">laboratory test</a> is to detect antibodies against WNV in the blood. However, WNV antibodies cross-react with dengue, Zika or other flaviviruses, so if this test is positive, an additional test is required to confirm the diagnosis. </p>
<p>This additional test is called the Plaque Reduction Neutralization Test or PRNT for short. It requires a live virus, so it must be done in a containment level 3 (CL3) laboratory. </p>
<p>The laboratory can also diagnose viral RNA using molecular tests, but interestingly, the virus often disappears from the blood when people exhibit symptoms. For encephalitic patients, cerebrospinal fluid can be used to detect the virus using molecular methods such as a polymerase chain reaction (PCR) test.</p>
<h2>Preventive measures</h2>
<p>There is no human vaccine for the West Nile virus. The most important preventive measure to avoid West Nile virus infection is to avoid mosquito bites. This seems simple but is often very challenging. </p>
<figure class="align-center ">
<img alt="Close-up view of a mosquito held with tweezers" src="https://images.theconversation.com/files/548224/original/file-20230914-17-vsdb54.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/548224/original/file-20230914-17-vsdb54.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/548224/original/file-20230914-17-vsdb54.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/548224/original/file-20230914-17-vsdb54.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/548224/original/file-20230914-17-vsdb54.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/548224/original/file-20230914-17-vsdb54.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/548224/original/file-20230914-17-vsdb54.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">A Culex tarsalis mosquito, a species that can transmit West Nile virus to humans, and is found across Canada.</span>
<span class="attribution"><span class="source">(AP Photo/Rick Bowmer)</span></span>
</figcaption>
</figure>
<p>People should use common sense during outdoor and indoor activities. Mosquito bites can be prevented by using bug spray, wearing protective clothing and avoiding areas that may have mosquitoes during the times when the species is most active, typically dusk and dawn. </p>
<p>A few species of mosquitoes can transmit WNV to humans. Among these, two of the most common species — the Culex pipiens and Culex tarsalis — are found across Canada, and their habitat is <a href="https://ncceh.ca/resources/evidence-reviews/impacts-canadas-changing-climate-west-nile-virus-vectors">predicted to expand with climate change</a>. Mosquitoes not only transmit WNV, but also transmit <a href="https://www.canada.ca/en/public-health/services/laboratory-biosafety-biosecurity/pathogen-safety-data-sheets-risk-assessment/california-serogroup-pathogen-safety-data-sheet.html">California serogroup viruses</a>, which cause encephalitis, as well as <a href="https://www.canada.ca/en/public-health/services/laboratory-biosafety-biosecurity/pathogen-safety-data-sheets-risk-assessment/eastern-equine-encephalitis.html">eastern equine encephalitis</a> viruses. </p>
<p>There is also no specific treatment for West Nile virus; medical management is supportive. Patients with severe symptoms often require pain control for headaches and medication and rehydration to treat nausea and vomiting. </p>
<p><a href="https://www.canada.ca/en/public-health/services/diseases/west-nile-virus/surveillance-west-nile-virus/west-nile-virus-weekly-surveillance-monitoring.html">So far in 2023</a>, only a <a href="https://www.cbc.ca/news/canada/hamilton/hamilton-west-nile-virus-2023-1.6957260">few human cases</a> have been identified in Ontario. However, a few mosquito pools in Manitoba and Ontario also tested positive, and also a few WNV-positive birds were found in Saskatchewan, Manitoba, Ontario and Québec.</p>
<p>No matter how many cases we are seeing, everyone is advised to take precautions against mosquito bites to avoid these life-threatening diseases.</p><img src="https://counter.theconversation.com/content/212955/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Muhammad Morshed 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>West Nile virus arrived in North America in 1999 and spread across the continent by 2005. Here’s what you need to know about this mosquito-borne pathogen.Muhammad Morshed, Clinical Professor, Department of Pathology and Laboratory Medicine, University of British ColumbiaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2124922023-09-13T10:55:07Z2023-09-13T10:55:07ZAddis Ababa faces growing climate change risks like heat, drought and floods, study warns<figure><img src="https://images.theconversation.com/files/545484/original/file-20230830-19-8bq04m.jpg?ixlib=rb-1.1.0&rect=0%2C7%2C5000%2C3315&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">About 70% of people in Addis Ababa live in informal settlements that are vulnerable to climate change. Amanuel Sileshi/AFP/</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/muslim-devotees-gather-at-meskel-square-to-break-their-fast-news-photo/1240330823?adppopup=true">Getty Images</a></span></figcaption></figure><p>Addis Ababa, Ethiopia’s capital city, will likely face increased heatwaves, droughts and severe flooding over the next 67 years. These changes will pose risks to public health and infrastructure. They’ll also be felt most acutely by the city’s most vulnerable residents: those living in informal settlements. </p>
<p>Addis Ababa is one of the fastest-growing cities in Africa, and its current metropolitan population of about 5.4 million is projected to reach close to <a href="https://worldpopulationreview.com/world-cities/addis-ababa-population">9 million</a> by 2035.</p>
<p>This increase in the city’s population will be absorbed by informal settlements, the prime destination for most migrants. And informal settlements are characterised by poor or non-existent infrastructure, and face the twin challenges of worsening climate change and poor urban environmental policy.</p>
<p>To investigate the city’s vulnerability to climate change, researchers at <a href="https://www.climatepolicylab.org/">Tufts University</a> and the <a href="https://www.woodwellclimate.org/">Woodwell Climate Research Center</a> analysed flood risk and temperature data for different time periods, projecting from the past to the future.</p>
<p>We predicted that the city’s extreme daily maximum temperatures would increase by about <a href="https://www.woodwellclimate.org/climate-risk-assessment-addis-ababa-ethiopia/">1.7°C over the period 2040-2060</a>, compared with 2000–2020. An increase of 1.7°C would result in a <a href="https://iopscience.iop.org/article/10.1088/1748-9326/aab827">rise</a> in the frequency, duration, and intensity of heatwaves. In addition, higher temperatures contribute to increased water vapour and transpiration. This will <a href="https://report.ipcc.ch/ar6syr/pdf/IPCC_AR6_SYR_LongerReport.pdf#page=16">threaten</a> health, ecosystems, infrastructure, livelihoods, and food supplies.</p>
<p>Certain southern neighbourhoods, such as <a href="https://www.woodwellclimate.org/climate-risk-assessment-addis-ababa-ethiopia/">Akaki-Kaliti, Bole and Nifas Silk-Lafto</a>, have experienced notably higher temperatures, especially during the warm season from March to May. And, looking to the future, temperature projections for <a href="https://www.woodwellclimate.org/climate-risk-assessment-addis-ababa-ethiopia/">Nifas Silk-Lafto suggest an average temperature increase to 26.21°C between 2040 and 2060, and further increase to 27.78°C from 2070 to 2090</a> and <a href="https://www.woodwellclimate.org/climate-risk-assessment-addis-ababa-ethiopia/">27.78°C from 2070 to 2090</a>. </p>
<p>For the warm-season months of March, April, and May, a temperature increase of 1.8°C is projected. This suggests that the peak temperature for the hottest day of the year will rise by an average of 1.8°C compared to recent data. From 2000 to 2020 the average temperature in the Nifas Silk-Lafto sub-city was 24.70°C. </p>
<p>Increases in temperatures of this magnitude will lead to public health challenges such as increased malaria risks, disproportionately affecting vulnerable groups like the elderly, children, and women.</p>
<h2>More droughts</h2>
<p>Over the past two decades, Addis Ababa has endured an average of three months of extreme drought yearly. Using the <a href="https://www.droughtmanagement.info/palmer-drought-severity-index-pdsi/">Palmer Drought Severity Index</a> to assess temperature and precipitation data in a geographical area, our analysis suggests that extreme drought events will become more frequent between 2040 and 2060. The city is expected to experience an additional 1.6 months of extreme drought annually, a 53% increase compared with 2000-2020. </p>
<p>This rising frequency of droughts, along with the city’s growing population, is intensifying water insecurity. Groundwater reserves for drought emergencies are already being <a href="https://onlinelibrary.wiley.com/doi/10.1002/tqem.21512">depleted</a>. </p>
<p>These droughts will affect health, hydroelectric energy production and urban agriculture. </p>
<h2>Flooding</h2>
<p>Too much rainfall, particularly if it occurs within a short period of time in an urban area, leads to flooding. Flooding poses a significant environmental risk to Addis Ababa, especially because the city has developed around three primary rivers. </p>
<p>Climate change will increase water-related challenges by affecting the flow of rivers and the replenishment of groundwater. </p>
<p>Currently, <a href="https://www.woodwellclimate.org/climate-risk-assessment-addis-ababa-ethiopia/">67%</a> of the population in Addis lives in flood prone areas. The parts of the city that are most at risk include central Addis, which has the greatest density of impervious surfaces like tarmac and concrete. These contribute to flood risk because water can’t seep into the ground.</p>
<p>Other <a href="https://www.woodwellclimate.org/climate-risk-assessment-addis-ababa-ethiopia/">parts of the city that are at risk</a> include the southern half – where the slope is relatively flatter, so water doesn’t flow away – and the Nifas Silk-Lafto region, where considerable development has taken place in the floodplain. </p>
<p>Several factors will add to the flooding challenge. The city has <a href="https://www.sciencedirect.com/science/article/pii/S2214581819301843">inadequate sewerage infrastructure</a> and <a href="https://onlinelibrary.wiley.com/doi/10.1111/jfr3.12629">weak drainage systems</a> which are often obstructed by solid waste. </p>
<h2>The impact</h2>
<p>The effects on the city’s residents will be substantial. </p>
<p>Health is just one example. </p>
<p>Our data show that average temperatures in the city will make year-round <a href="https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.2003489#:%7E:text=This%20model%20suggests%20a%20temperature,climate%20change%20on%20malaria%20transmission">malaria transmission</a> a risk. There will have to be sustained policy measures to deal with the risk.</p>
<p>Older adults and pregnant women are particularly vulnerable to the health impacts of climate change. The elderly are more <a href="https://www.ohchr.org/en/climate-change/impact-climate-change-rights-older-persons">sensitive</a> to heat and pollution due to existing health conditions, limited mobility, and compromised immune systems. Pregnant women face <a href="https://www.sciencedirect.com/science/article/pii/S0015028222003831">risks</a> from thermal variations and mosquito-borne illnesses like malaria and Zika. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/climate-change-will-cause-more-african-children-to-die-from-hot-weather-188609">Climate change will cause more African children to die from hot weather</a>
</strong>
</em>
</p>
<hr>
<p>Many urban residents will be prone to increasing floods. Already <a href="https://www.woodwellclimate.org/climate-risk-assessment-addis-ababa-ethiopia/">10%</a> of the city’s newly developed areas are within a 100-year floodplain, threatening lives and infrastructures.</p>
<p>People living in informal settlements are particularly at risk – that’s about <a href="https://unhabitat.org/ethiopia-addis-ababa-urban-profile">70%</a> of Addis Ababa’s residents. These settlements crop up in limited and unused spaces, such as riverbanks. They are at a higher <a href="https://gsdrc.org/topic-guides/urban-governance/key-policy-challenges/informal-settlements/">risk</a> of flood impact, and the risk is growing.</p>
<p>Our data shows that currently the percentage difference in vulnerability between formal and informal settlements is <a href="https://www.woodwellclimate.org/climate-risk-assessment-addis-ababa-ethiopia/">0.6%</a>. The figure illustrates the extent to which buildings within formal and informal settlements would be affected by flooding events. It is expected to rise to <a href="https://www.woodwellclimate.org/climate-risk-assessment-addis-ababa-ethiopia/">1.3% by 2050 and 1.6% by 2080</a>. </p>
<h2>Policy recommendations</h2>
<p>There’s an urgent need for policies that can rise to these challenges. We suggest:</p>
<ul>
<li><p>the government should establish a climate adaptation and resilience office, to integrate <a href="https://www.c2es.org/document/what-is-climate-resilience-and-why-does-it-matter/">climate resilience</a> into <a href="https://theconversation.com/cape-towns-climate-strategy-isnt-perfect-but-every-african-city-should-have-one-149287">urban planning</a></p></li>
<li><p>an independent body should then assess policies in practice</p></li>
<li><p>a water management strategy to ensure equitable access and sustainable <a href="https://waterfdn.org/sustainable-water-management-swm-profile/#:%7E:text=Sustainable%20water%20management%20means%20using,those%20needs%20in%20the%20future.">use of water</a></p></li>
<li><p>the city should invest in <a href="https://environment.ec.europa.eu/topics/nature-and-biodiversity/green-infrastructure_en">green infrastructure</a> </p></li>
</ul>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/global-climate-finance-leaves-out-cities-fixing-it-is-critical-to-battling-climate-change-194375">Global climate finance leaves out cities: fixing it is critical to battling climate change</a>
</strong>
</em>
</p>
<hr>
<ul>
<li><p>upgrading infrastructure and improving waste management</p></li>
<li><p>public awareness campaigns and <a href="https://www.unesco.org/en/climate-change/education#:%7E:text=Education%20is%20crucial%20to%20promote,act%20as%20agents%20of%20change.">school</a> education on climate change impacts</p></li>
<li><p>developing mechanisms for effective <a href="https://coastadapt.com.au/how-to-pages/collaboration-and-partnerships-climate-change-adaptation">collaboration</a> among government departments, non-governmental organisations and international agencies.</p></li>
</ul><img src="https://counter.theconversation.com/content/212492/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Abay Yimere 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>Climate change is putting pressure on Ethiopia’s largest city, Addis Ababa, and exposing people to disease and natural disasters.Abay Yimere, Postdoctoral Scholar in International Environment and Resource Policy, The Fletcher School, Tufts UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2070882023-07-10T12:31:42Z2023-07-10T12:31:42ZNot all repellents are equal – here’s how to avoid mosquito bites this summer<figure><img src="https://images.theconversation.com/files/533800/original/file-20230623-17-1mi6af.jpg?ixlib=rb-1.1.0&rect=6%2C42%2C4019%2C2975&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A group of Anopheles mosquitoes taking a blood meal in an experiment conducted by the New Mexico State University Molecular Vector Physiology Lab. </span> <span class="attribution"><span class="source">Hansen MVP lab</span></span></figcaption></figure><p>Now that summer is in full swing, mosquitoes have come out across the United States. The use of mosquito repellents can protect both your health and sanity this summer.</p>
<p>While mosquitoes leave bothersome, itchy bites on your skin, they can also pose a serious and sometimes deadly risk to your health. When a mosquito bites you, it may transmit harmful pathogens that cause dangerous diseases like <a href="https://www.cdc.gov/parasites/malaria/index.html">malaria</a>, <a href="https://www.cdc.gov/dengue/">dengue fever</a>, <a href="https://www.cdc.gov/zika/">Zika</a> and <a href="https://www.cdc.gov/westnile/">West Nile</a>. </p>
<h2>Avoiding mosquito bites</h2>
<p>Mosquito females bite people to get vital nutrients from our blood. They then use these nutrients <a href="https://doi.org/10.3389/fphys.2014.00103">to make their eggs</a>. One single blood meal can give rise to about 100 mosquito eggs that hatch into wiggling larvae.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/532446/original/file-20230616-17-op8jl0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532446/original/file-20230616-17-op8jl0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=448&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532446/original/file-20230616-17-op8jl0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=448&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532446/original/file-20230616-17-op8jl0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=448&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532446/original/file-20230616-17-op8jl0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=563&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532446/original/file-20230616-17-op8jl0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=563&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532446/original/file-20230616-17-op8jl0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=563&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"><em>Culex quinquefasciatus larvae</em> Mosquito larvae feed by filtering food from water. Getting rid of standing water can reduce mosquito habitats.</span>
<span class="attribution"><span class="source">Immo Hansen</span></span>
</figcaption>
</figure>
<p>There are several ways to <a href="https://www.cdc.gov/mosquitoes/mosquito-bites/prevent-mosquito-bites.html">avoid getting bitten by mosquitoes</a>, from wearing long, loose clothing and limiting time outside to placing screens over your windows and getting rid of standing water that mosquitoes might use to breed.</p>
<p>However, one of the best ways to protect yourself when you’re going to a place where hungry mosquitoes will be buzzing around is by using <a href="https://doi.org/10.1093/jisesa/iev125">mosquito repellents</a>. </p>
<p>Our team at the <a href="https://nmsu.edu/">New Mexico State University</a> <a href="https://www.hansenmvplab.com/">Molecular Vector Physiology Laboratory</a> has studied different types of mosquito repellents and their efficacy for over a decade. Here’s what you need to know to protect yourself this summer:</p>
<h2>All about repellents</h2>
<p>The use of mosquito repellents goes far back in history, certainly predating written historical accounts. <a href="https://doi.org/10.1201/9781420006650">Some of the oldest records</a> of the use of mosquito repellents date back to early Egyptian and Roman history. During this period, smoke from smudge fires was often used to repel mosquitoes. </p>
<p>Today, we have more options than our ancestors when it comes to choosing what type of mosquito repellent to use – <a href="https://www.nytimes.com/wirecutter/reviews/best-bug-repellent/">sprays and lotions</a>, candles, <a href="https://www.nytimes.com/wirecutter/reviews/mosquito-control-gear/">coils and vaporizers</a>, to name some. </p>
<p>These repellents interfere with a mosquito’s <a href="https://doi.org/10.1016/j.cub.2019.04.004">sense of smell, taste or both</a>. The repellent either blocks or overstimulates these senses. Scientists understand how certain repellents like DEET <a href="https://doi.org/10.1016/j.neuron.2010.07.006">work at the molecular level</a>, but for many of them, it is still unknown why exactly they repel mosquitoes.</p>
<h2>Testing repellents</h2>
<p>We used a variety of <a href="https://www.hansenmvplab.com/services">scientific laboratory experiments and field tests</a> to find out what works. For some products, testing was as simple as putting a volunteer’s treated arm into a cage with 25 mosquitoes and waiting for the first mosquito bite. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532472/original/file-20230616-19-qwfotj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A researcher's arm covered in a protective sleeve, with part of their skin exposed while mosquitoes fly around." src="https://images.theconversation.com/files/532472/original/file-20230616-19-qwfotj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532472/original/file-20230616-19-qwfotj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=336&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532472/original/file-20230616-19-qwfotj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=336&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532472/original/file-20230616-19-qwfotj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=336&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532472/original/file-20230616-19-qwfotj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=422&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532472/original/file-20230616-19-qwfotj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=422&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532472/original/file-20230616-19-qwfotj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=422&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Arm-in-cage experimental setup.</span>
<span class="attribution"><span class="source">Keyla R. Salas</span></span>
</figcaption>
</figure>
<p>For others, like citronella candles, we used a <a href="https://www.krwg.org/krwg-news/2022-09-23/research-at-nmsu-looks-at-the-effectiveness-of-mosquito-repellents">slow-speed wind tunnel</a> and put a candle or device between a person and a cage of mosquitoes. Depending on the repellent efficacy of the device, mosquitoes either flew toward the person or away. Another experiment we conducted was the <a href="https://www.youtube.com/watch?v=38gVZgE39K8&t=23s">Y-tube choice assay</a> where mosquitoes chose to fly toward someone’s hand or, if repelled, fly toward the blank or empty option. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/38gVZgE39K8?wmode=transparent&start=23" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">This video from the YouTube channel Veritasium shows our team performing a Y-tube choice assay experiment.</span></figcaption>
</figure>
<h2>Mosquito repellents that don’t work</h2>
<p>Bracelets don’t work. Department stores and pharmacy chains sell hundreds of different varieties of bracelets. They are marketed as “mosquito repellent” bands, wristbands and watches, and their materials can vary from plastic to leather. Even if they are loaded with repellents, they can’t protect your whole body from mosquito bites. </p>
<p>Ultrasonic repellent devices don’t work. These come as electrical plug-ins, free-standing varieties or watchlike accessories that claim to emit a high-frequency sound that deters mosquitoes by mimicking bats. However, in <a href="https://doi.org/10.1111/j.1570-8703.2006.00463.x">scientific studies</a>, ultrasonic repellent devices fail to repel mosquitoes. In fact, when our lab <a href="https://doi.org/10.1093/jisesa/iew117">tested one of these devices</a>, we found a slight increase in mosquito attraction to the wearer. </p>
<p>Dietary supplements – vitamin B, garlic and so on – don’t work. No scientific evidence shows these supplements <a href="https://doi.org/10.1056/NEJMoa011699">protect people from mosquito bites</a>. </p>
<p>Light-based repellents don’t work. These devices come as colored light bulbs, and they don’t attract insects that fly toward white light. This approach works well on <a href="https://doi.org/10.1007/s13355-013-0219-x">moths, beetles and stinkbugs</a>, but not on mosquitoes. </p>
<h2>Mosquito repellents that work</h2>
<p>And here is our ranking of what does work, starting with the best repellent/active ingredient.</p>
<ol>
<li><p>DEET works. DEET, <a href="https://www.epa.gov/insect-repellents/deet">chemical name, N,N-diethyl-meta-toluamide</a>, was developed in the 1950s by the U.S. Army and is a <a href="https://doi.org/10.1081/CLT-120025348">well-established</a> mosquito repellent with a <a href="https://doi.org/10.1016/j.jaad.2007.10.005">long history of use</a>. The higher the percentage, the longer the protection time is – <a href="https://www.hindawi.com/journals/jpr/2015/361021/">up to six hours</a>.</p></li>
<li><p>Picaridin works. This synthetic repellent can protect for <a href="https://link.springer.com/article/10.1007/s00436-006-0450-2">up to six hours at a 20% concentration</a>. This repellent is a <a href="https://www.outdoors.org/resources/amc-outdoors/outdoor-resources/picaridin-vs-deet-which-is-the-best-insect-repellent/">promising alternative</a> for <a href="https://accpjournals.onlinelibrary.wiley.com/doi/full/10.1002/phar.1854">DEET</a>.</p></li>
<li><p>Oil of lemon eucalyptus, or OLE, works. OLE, with the active ingredient PMD, is a plant-based alternative to DEET and picaridin. Its repellent properties can last for <a href="https://academic.oup.com/jinsectscience/article/15/1/140/2583458">up to six hours</a>.</p></li>
<li><p>Other essential oils – some work, some not so much. We applied <a href="https://doi.org/10.1038/s41598-023-28820-9">20 different essential oils</a> in a 10% essential oil lotion mixture to volunteers’ skin. Here’s what we found: </p>
<p>Clove oil works. This oil, with the active ingredient eugenol, can protect from mosquito bites for over 90 minutes at a 10% concentration in lotion. Cinnamon oil works. This oil, with the active ingredients cinnamaldehyde and eugenol, can protect from mosquitoes for over 60 minutes at a 10% concentration in lotion. Geraniol and 2-PEP, or 2-phenylethyl propionate, work for about 60 minutes at a 10% concentration in lotion. Citronella oil works, just not so great. We found citronella oil at a 10% concentration only protected from mosquito bites for about 30 minutes. </p></li>
</ol>
<p><iframe id="vwJXh" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/vwJXh/2/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>If you are planning to mix your own plant-based mosquito repellent this summer, remember that essential oils are <a href="https://www.mdpi.com/2297-8739/10/2/128">complex mixtures of plant-made chemicals</a> that can cause skin irritations at high concentrations.</p>
<p>Based on our study, we recommend using repellents with the active ingredient DEET if you live in or are traveling to regions with a high risk of vector-borne disease transmission. However, plant-based repellents will work just fine to prevent nuisance mosquito bites in low-risk areas, as long as you reapply them as needed.</p><img src="https://counter.theconversation.com/content/207088/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Immo A. Hansen receives funding from the National Institute of Health. </span></em></p><p class="fine-print"><em><span>Hailey A. Luker receives funding from the National Institute of Health.</span></em></p>Two mosquito physiology experts explain which repellents work better than others and how to protect yourself this summer.Immo A. Hansen, Professor of Biology, New Mexico State UniversityHailey A. Luker, Ph.D. Student in Biology, New Mexico State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1940662022-11-10T13:47:06Z2022-11-10T13:47:06ZClimate change affects mosquito behaviour. This may make it harder to end malaria in South Africa<figure><img src="https://images.theconversation.com/files/494228/original/file-20221108-20-5pc5g2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Global climate is changing rapidly. This has a range of public health implications. </span> <span class="attribution"><span class="source">CDC/ James Gathany</span></span></figcaption></figure><p>Changes in climatic factors – such as higher temperatures and increased rainfall – affect the developmental, behavioural and distribution patterns of <a href="https://theconversation.com/what-a-warmer-wetter-world-means-for-insects-and-for-what-they-eat-166509">insects</a> like mosquitoes. These changes have serious implications for the effective control of insect-borne diseases such as malaria.</p>
<p>Worryingly, temperatures across southern Africa are predicted to increase by at least <a href="https://www.climatelinks.org/sites/default/files/asset/document/Southern%20Africa%20Climate%20Info%20Fact%20Sheet_FINAL.pdf">0.8⁰C by 2035</a>.</p>
<p>Malaria is currently present in three provinces in South Africa: Limpopo, Mpumalanga and KwaZulu-Natal. Limpopo reports 62% of the local cases, while KwaZulu-Natal reports only <a href="https://malariaelimination8.org/south-africa">6%</a>.</p>
<p>Over the past 50 years annual temperatures in South Africa have been increasing significantly faster than the <a href="https://www.climatelinks.org/sites/default/files/asset/document/Southern%20Africa%20Climate%20Info%20Fact%20Sheet_FINAL.pdf">global average</a>. The increases have been most extreme in Limpopo, where temperatures have risen by an average of 0.12⁰C every decade. Small annual shifts have big effects.</p>
<p>These higher temperatures increase the malaria risk. This is because the malaria mosquito and parasite are happiest at <a href="https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.2003489">temperatures</a> between 17⁰C and 35⁰C. </p>
<p>Warmer weather means vector mosquitoes are able to <a href="https://parasitesandvectors.biomedcentral.com/articles/10.1186/s13071-019-3391-1#:%7E:text=albopictus%20intrinsic%20rate%20of%20growth,females%20in%2027%20%C2%B0C.">develop faster</a>, invade new locations, and spread <a href="https://wellcome.org/news/how-climate-change-affects-vector-borne-diseases">vector-borne diseases</a>.</p>
<p>In addition, increased rainfall will potentially increase the number of mosquito vector <a href="https://wellcome.org/news/how-climate-change-affects-vector-borne-diseases">breeding sites</a>. Vector mosquitoes like those that transmit malaria breed in stagnant and temporary bodies of water. Research in Limpopo has <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6950450/">shown</a> that heavy rains in spring are usually associated with higher malaria case numbers during summer. </p>
<p>The impact of climate change on mosquitoes is very clear. But its impact on malaria transmission is still unclear. Some theoretical mathematical modelling studies <a href="https://www.sciencedirect.com/science/article/abs/pii/S003592030600263X">predict</a> an uptick in malaria case numbers due to climate change. But other models suggest climate change will have <a href="https://www.nature.com/articles/415905a">no impact on malaria</a>. More data are needed to see which model is correct. This is because the effect is difficult to test in the laboratory. </p>
<p>Whether climate change will present another challenge to achieving malaria elimination is yet to be confirmed. Our <a href="https://www.nicd.ac.za/centres/centre-for-emerging-zoonotic-and-parasitic-diseases/">research group</a> is currently trying to address this knowledge gap.</p>
<h2>What we do know</h2>
<p>The relationship between climate change and malaria is complicated. But four things are clear: as the Earth warms up the malaria vector will develop faster, allowing them to breed faster, bite <a href="https://wellcomeopenresearch.org/articles/2-102#ref-35">more frequently</a> and expand into formerly unsuitable habitats. </p>
<p>This means that mosquito larvae will develop into adults faster. The sooner the female bites, the sooner she can transmit the disease. If she bites more frequently, she will spread more disease. </p>
<p>The malaria parasite’s development inside the mosquito is highly dependent on temperature. At temperatures <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5658182/">below 17⁰C, and above 35⁰C</a>, the parasite’s life cycle inside the mosquito cannot be completed. This halts the onward transmission of malaria. </p>
<p>The mosquito’s transformation from larva to free-flying adult generally occurs at temperatures between <a href="https://www.cambridge.org/core/journals/bulletin-of-entomological-research/article/abs/effect-of-temperature-on-the-development-of-the-aquatic-stages-of-anopheles-gambiae-sensu-stricto-diptera-culicidae/6375ECAEF9B542ABB63F074E0972C855">22⁰C and 34⁰C</a>. Interestingly, research has <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3146900/">shown</a> that mosquitoes can change their behaviour to spend most of their time resting in cooler spaces. This way they can survive when ambient temperatures increase. This behaviour of the mosquito can help the parasite survive temperatures that would otherwise stop its development. </p>
<p>Distinct changes in the <a href="https://geographical.co.uk/climate-change/as-the-world-warms-the-seasons-are-shifting">seasons</a>, largely due to climate change, have been noted. The <a href="https://www.climatelinks.org/sites/default/files/asset/document/Southern%20Africa%20Climate%20Info%20Fact%20Sheet_FINAL.pdf">southern African region</a> is experiencing more frequent extreme heat days and fewer extreme cool days.</p>
<p>Therefore, winters are becoming much warmer, allowing mosquitoes to breed and transmit malaria in larger numbers during the winter months. Summer months are also getting hotter. In some cases, the summers may get too hot for mosquito and parasite growth, preventing malaria transmission. Climate change could cause a shift in the malaria transmission season from the summer months to the traditionally cooler autumn and winter months.</p>
<p>Rainfall also plays a major role in malaria transmission. In general, malaria incidence decreases during the El Niño (hotter but drier) years and increases in the La Niña (cooler but wetter) <a href="https://www.sciencedirect.com/science/article/abs/pii/S003592030600263X">years</a>. This is particularly true in countries like South Africa, where the adaptable malaria vector, <em>Anopheles arabiensis</em>, is a dominant transmitting vector. South Africa is currently in a La Niña cycle, so the upcoming malaria season (October to February) could potentially be significant, given the more favourable conditions for malaria transmission and the relaxation of all COVID-related restrictions on movement. </p>
<h2>The South African situation</h2>
<p>Our research group based at the <a href="https://www.nicd.ac.za/centres/centre-for-emerging-zoonotic-and-parasitic-diseases/">National Institute for Communicable Diseases</a> and the University of Witwatersrand’s <a href="https://www.wits.ac.za/wrim/">Research Institute for Malaria</a> was involved in identifying the mosquitoes behind the malaria epidemic of <a href="https://resjournals.onlinelibrary.wiley.com/doi/abs/10.1046/j.1365-2915.2000.00234.x?sid=nlm%3Apubmed">2000</a>. This outbreak coincided with severe <a href="https://earth.esa.int/web/earth-watching/natural-disasters/floods/content/-/asset_publisher/zaoP2lUloYKv/content/flood-mozambique-february-2000/">flooding</a> in southern Mozambique. The dramatic increase in available breeding sites allowed an insecticide-resistant mosquito from Mozambique, <em>Anopheles funestus</em>, to reinvade KwaZulu-Natal, driving malaria case numbers up.</p>
<p>Since this outbreak, our group has been conducting <a href="https://sajs.co.za/article/view/11755">intensive surveillance</a> in South Africa’s endemic provinces. We’ve also been involved in research to understand the impact of climate change on malaria transmission in South Africa. </p>
<p>Research from our vector laboratories has <a href="https://malariajournal.biomedcentral.com/articles/10.1186/s12936-018-2250-4">demonstrated</a> that a warmer world would reduce the effectiveness of insecticides used for indoor residual spraying. In addition, insecticide resistant mosquitoes <a href="https://malariajournal.biomedcentral.com/articles/10.1186/s12936-017-1720-4%20">seem better adapted</a> to surviving the warmer conditions than mosquitoes that are sensitive to insecticides.</p>
<p>Modelling experiments <a href="https://previous.iiasa.ac.at/web/scientificUpdate/2014/Abiodun_Gbenga.html">suggest</a> that humidity levels will also influence malaria transmission in South Africa. But this needs to be confirmed under laboratory conditions using live mosquitoes.</p>
<h2>What needs to be done?</h2>
<p>It is clear that the relationship between climate change and malaria is complex. More work needs to be done to understand this relationship so effective control measures can be put in place. Crucially, malaria hotspots should be targeted for surveillance in order to understand the role of microclimate on <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3146900/">malaria transmission</a>. Microclimate is a set of local climate conditions that may differ from the climate in general. </p>
<p>At present, there is no evidence that the <a href="https://www.nicd.ac.za/wp-content/uploads/2018/12/south_africa_malaria_risk_dec2018_final.pdf">malaria-risk areas</a> in South Africa have expanded. However, regardless of the climate or whether you have travelled this summer, it is critical to think about malaria when it comes to unexplained fevers. <a href="https://www.nicd.ac.za/uploads/2017/03/Malaria-FAQ-NICD-Nov-2018.pdf">Know</a> what the symptoms of malaria are, how to reduce the risk of being infected, and what to do if you suspect that you have malaria.</p><img src="https://counter.theconversation.com/content/194066/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Shüné Oliver receives funding from the National Research Foundation of South Africa, the National Health Laboratory Services Research Trust and the Female Academic Fellowship (FALF). </span></em></p><p class="fine-print"><em><span>Jaishree Raman is affiliated with National Institute for Communicable Diseases, the Wits Research Institute for Malaria and the UP Institute for Sustainable Malaria Control. She receives funding from the Global Fund, the Bill and Melinda Gates Foundation, the South African Medical Research Council, the South Africa Research Trust, the National Research Foundation and the National Institute for Communicable Diseases.</span></em></p>As the Earth warms up the malaria vector will develop faster, allowing them to breed faster, bite more frequently and expand into formerly unsuitable habitats.Shüné Oliver, Medical scientist, National Institute for Communicable DiseasesJaishree 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/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/1625572021-08-18T12:10:46Z2021-08-18T12:10:46ZTick bites: Every year is a bad tick year<figure><img src="https://images.theconversation.com/files/412506/original/file-20210721-21-owelob.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Black-legged ticks carry Lyme disease, which continues to spread widely across the United States.</span> <span class="attribution"><a class="source" href="https://www.cdc.gov/ticks/gallery/index.html#anchor_1592235021091">CDC/Michael Levin</a></span></figcaption></figure><p>It’s summer, a time to hike, garden, vacation – and to be on the lookout for ticks. </p>
<p>From Lyme disease to lesser-known illnesses like <a href="https://www.cdc.gov/heartland-virus/index.html">Heartland virus disease</a>, <a href="https://www.cdc.gov/ehrlichiosis/index.html">ehrlichiosis</a> and <a href="https://www.cdc.gov/coloradotickfever/index.html">Colorado tick fever</a>, tick-borne disease cases are <a href="https://www.cdc.gov/media/dpk/diseases-and-conditions/lyme-disease/index.html">increasing rapidly</a> in the United States. </p>
<p>In 2017, <a href="https://www.cdc.gov/media/releases/2018/s1114-record-number-tickborne-diseases.html">59,349 cases</a> were reported to the U.S. Centers for Disease Control and Prevention, an all-time high. Yet, this represents just a fraction of infections because those who don’t exhibit symptoms or fail to seek treatment remain uncounted. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7853543/">A recent report</a> estimated nearly a half-million Lyme disease cases per year in the U.S., with numbers <a href="https://dx.doi.org/10.15585%2Fmmwr.mm6717e1">more than doubling</a> from 2004 to 2016.</p>
<p>As a biologist who <a href="https://scholar.google.com/citations?user=60syUy0AAAAJ&hl=en">studies tick-borne disease</a>, I am asked each spring and summer whether it will be a bad year for ticks. The answer: It is never a good year for ticks. There may be relatively few of certain species and many of other types. Different species of ticks live in different environments. Many factors influence numbers, from <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/ele.13590">dwindling biodiversity</a> and <a href="https://academic.oup.com/jme/article-abstract/58/4/1546/5936773">ecological change</a> to the <a href="https://ehp.niehs.nih.gov/doi/full/10.1289/EHP5668">changing climate</a>. But every year, the time to be most vigilant is early spring through late fall. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/412509/original/file-20210721-19-tf54sj.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/412509/original/file-20210721-19-tf54sj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/412509/original/file-20210721-19-tf54sj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=239&fit=crop&dpr=1 600w, https://images.theconversation.com/files/412509/original/file-20210721-19-tf54sj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=239&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/412509/original/file-20210721-19-tf54sj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=239&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/412509/original/file-20210721-19-tf54sj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=300&fit=crop&dpr=1 754w, https://images.theconversation.com/files/412509/original/file-20210721-19-tf54sj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=300&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/412509/original/file-20210721-19-tf54sj.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=300&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">Michigan, Wisconsin and the Northeast are hot spots for tick-borne disease in the U.S.</span>
<span class="attribution"><a class="source" href="https://www.cdc.gov/vitalsigns/vector-borne/infographic.html#graphic3">CDC</a></span>
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<h2>Different species, different patterns</h2>
<p>There are at least <a href="https://www.cdc.gov/ticks/geographic_distribution.html">seven tick species</a> in North America that commonly bite and infect humans and animals with numerous <a href="https://www.cdc.gov/ticks/tickbornediseases/overview.html">diseases</a>. But there are others, too. Over the past two decades, seven new tick-borne germs have been identified in the U.S., including a newly discovered Lyme disease <a href="https://www.cdc.gov/lyme/mayonii/index.html">bacterium</a> found in the Upper Midwest and Bourbon virus, discovered in Bourbon County, Kansas.</p>
<p>Some regions, like where I work in Richmond, Virginia, are home to multiple human-biting species, each with its own suite of pathogens and habitat preferences. <a href="https://www.neha.org/vector/black-legged-tick-or-deer-tick">Black-legged ticks</a>, which spread Lyme and other diseases, are of greatest concern. They are common in forests across the <a href="https://www.cdc.gov/ticks/geographic_distribution.html">Eastern U.S.</a>. The bite of an infected <a href="https://www.neha.org/vector/american-dog-tick">American dog tick</a>, which prefer <a href="https://www.cdc.gov/ticks/geographic_distribution.html">grassy areas</a>, can infect people and dogs with Rocky Mountain spotted fever. Aggressive <a href="https://www.neha.org/vector/lone-star-tick">Lone Star ticks</a>, which can transmit <a href="https://doi.org/10.1093/infdis/161.4.609">ehrlichiosis</a> and <a href="https://www.cdc.gov/tularemia/index.html">tularemia</a>, thrive in many habitats across the <a href="https://theconversation.com/drafts/162557/edit#">eastern U.S.</a>, and can survive hot, dry conditions. </p>
<h2>Complex life cycles</h2>
<p>These parasitic arthropods are more closely related to mites, spiders and scorpions than to insects. Ticks spend <a href="https://www.sciencedirect.com/science/article/pii/S002571250300083X?via%3Dihub">most of their time</a> on the ground in leaf litter or vegetation, undergoing a <a href="https://www.cdc.gov/ticks/life_cycle_and_hosts.html">four-stage metamorphosis</a>. </p>
<p>Eggs hatch into six-legged larvae and attach to a host. Then they drop off and molt into eight-legged nymphs, find a host and grow into reproductive adults. Much of their lives are spent waiting, inactive, for warmer or more humid weather to continue development, or on the hunt for their next meal. </p>
<p>Mortality is high. If just 10% of ticks survived each life stage, it would take 2,000 eggs to produce a pair of reproductive adults. Small changes in survival can affect populations for years.</p>
<p>Most of the hard-bodied, blood-feeding ticks that carry disease take only three bloodmeals during their entire <a href="https://www.sciencedirect.com/science/article/pii/S002571250300083X?via%3Dihub">two- to three-year life cycle</a> – meals that allow them to molt into the next stage, or to lay eggs. </p>
<p>They <a href="https://www.cdc.gov/ticks/life_cycle_and_hosts.html">feed</a> on mammals, birds, reptiles and amphibians. Most ticks prefer a different host at each stage of their life, finding it by detecting an animal’s breath or smell, sensing body heat, moisture or vibrations. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/412476/original/file-20210721-15-1fehf87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/412476/original/file-20210721-15-1fehf87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/412476/original/file-20210721-15-1fehf87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=500&fit=crop&dpr=1 600w, https://images.theconversation.com/files/412476/original/file-20210721-15-1fehf87.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=500&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/412476/original/file-20210721-15-1fehf87.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=500&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/412476/original/file-20210721-15-1fehf87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=629&fit=crop&dpr=1 754w, https://images.theconversation.com/files/412476/original/file-20210721-15-1fehf87.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=629&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/412476/original/file-20210721-15-1fehf87.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=629&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 life cycle of a black-legged tick is generally two years.</span>
<span class="attribution"><a class="source" href="https://www.cdc.gov/ticks/life_cycle_and_hosts.html">CDC</a></span>
</figcaption>
</figure>
<p>The numbers of <a href="https://royalsocietypublishing.org/doi/full/10.1098/rsbl.2016.0463">available hosts</a> may be a key factor in tick abundance, which is sometimes influenced by natural cycles. For example, during <a href="https://www.natureworldnews.com/articles/17888/20151030/acorns-mast-years-masses-why.htm">“mast” years</a> when acorns are plentiful, white-footed mice populations grow along with black-legged ticks that feed on them, and <a href="https://www.washingtonpost.com/weather/2019/05/22/tick-population-is-booming-is-climate-change-responsible-will-tick-borne-disease-increase/">Lyme disease cases</a> also tend to rise.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Onx5MTm0RSY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Lyme disease experts warn that ticks are spreading.</span></figcaption>
</figure>
<h2>Expanding territory</h2>
<p>Predicting tick numbers grows harder as many species expand their ranges. Altered ecosystems play a substantial role. <a href="https://theconversation.com/how-the-lyme-disease-epidemic-is-spreading-and-why-ticks-are-so-hard-to-stop-123142">Lyme disease</a> became epidemic when mice that carry the bacterium proliferated and deer were reintroduced for hunting in the 1900s after a steep decline; deer act as hosts for adult black-legged ticks that spread the disease. Migrating birds have also helped <a href="https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/090062">disperse ticks</a> along the Atlantic flyway. </p>
<p><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5877023/">Changing climate</a>, with shorter, milder winters, may increase tick survival, creating larger populations. Shorter, warmer winters have allowed some species to move northward. The two Lyme-spreading tick species now live in at least <a href="https://doi.org/10.1093/jme/tjv237">43 states</a>. <a href="https://entnemdept.ufl.edu/creatures/urban/medical/gulf_coast_tick.htm">Gulf Coast</a> ticks have spread north to Delaware and Illinois, and the Lone Star tick <a href="https://ehp.niehs.nih.gov/doi/full/10.1289/EHP5668">may soon reach Canada</a>.</p>
<p>However, warming trends may have mixed impacts. Ticks need moisture as well as blood to survive; hot, dry weather kills some species, but not others.</p>
<h2>The forecast</h2>
<p>While researchers have identified why their numbers change over space and time, predicting risk is difficult. But we do know that tick-borne diseases will continue to be a human and veterinary health threat. Ancient ticks once <a href="https://www.scmp.com/news/world/article/2124078/ancient-ticks-engorged-dinosaur-blood-are-found-trapped-amber">fed on dinosaurs</a>. Scientists discovered fossilized ticks, some 15 million years old, that carried the <em>Borrelia</em> bacteria that causes Lyme disease, showing that it <a href="https://today.oregonstate.edu/archives/2014/may/amber-discovery-indicates-lyme-disease-older-human-race">existed long before humans</a>. </p>
<p>From a public health perspective, the most important question about ticks is not whether a given year will be particularly bad in terms of tick numbers, but what can be done to <a href="https://www.cdc.gov/ncezid/dvbd/media/stopticks.html">reduce the risk</a> of encountering these parasites to avoid illness. </p>
<p>[<em>The Conversation’s science, health and technology editors pick their favorite stories.</em> <a href="https://theconversation.com/us/newsletters/science-editors-picks-71/?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=science-favorite">Weekly on Wednesdays</a>.]</p><img src="https://counter.theconversation.com/content/162557/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jory Brinkerhoff receives, or recently received, funding from the National Institutes of Health, the Jeffress Memorial Trust, and the Fulbright Program, and the US Department of Agriculture. </span></em></p>How bad are ticks this year? An expert explains why tick-borne diseases are on the rise.Jory Brinkerhoff, Associate Professor of Biology, University of RichmondLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1391042020-05-27T12:20:11Z2020-05-27T12:20:11ZLyme disease symptoms could be mistaken for COVID-19, with serious consequences<figure><img src="https://images.theconversation.com/files/337500/original/file-20200526-106862-15q5xan.jpg?ixlib=rb-1.1.0&rect=0%2C3%2C1280%2C921&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Ticks like this one, shown magnified with an electron microscope, can transmit bacteria that cause severe illnesses in humans.</span> <span class="attribution"><a class="source" href="https://biology.richmond.edu/research/research-labs/brinkerhoff-lab.html">Fernando Otalora-Luna/University of Richmond</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Summer is field season for <a href="https://biology.richmond.edu/faculty/jbrinker/">ecologists like me</a>, a time when my colleagues, students and I go out into fields and woods in search of ticks to study the patterns and processes that allow disease-causing microbes – primarily bacteria and viruses – to spread among wildlife and humans. </p>
<p>That field work means we’re also at risk of getting the very diseases we study. I always remind my crew members to pay close attention to their health. If they get a fever or any other signs of sickness, they should seek medical treatment immediately and tell their doctor that they may have been exposed to ticks.</p>
<p>When summer <a href="http://doi.org/10.1128/JVI.01680-06">flu-like illnesses</a> develop in anyone who spends time outdoors in areas where ticks are common, tick-transmitted diseases like Lyme disease should be considered a likely culprit. </p>
<p>This summer, however, the global emergence of the novel coronavirus and COVID-19 is presenting a whole new set of challenges for diagnosing Lyme disease and other tick-borne illnesses. </p>
<p>Lyme disease <a href="https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/symptoms.html">shares a number of symptoms</a> with COVID-19, including fever, achiness and chills. Anyone who mistakes Lyme disease for COVID-19 could unknowingly delay necessary medical treatment, and that can lead to severe, potentially debilitating symptoms.</p>
<h2>Delaying medical treatment can be dangerous</h2>
<p>As we move from spring into summer, and into the peak period of tick activity in much of the Northern Hemisphere, time spent outdoors will increase, as will risk of tick-transmitted disease.</p>
<p>In some cases, there are key symptoms of a tick-transmitted disease that can help with diagnosis. For example, early Lyme disease, which is caused by the bite of an infected black-legged tick, sometimes called the deer tick, is commonly associated with an expanding “bull’s-eye rash.” <a href="https://www.cdc.gov/lyme/signs_symptoms/index.html">Seventy percent to 80% of patients have this symptom</a>. </p>
<p>However, <a href="https://www.cdc.gov/lyme/signs_symptoms/index.html">other symptoms</a> of Lyme disease – fever, head and body aches and fatigue – are less distinctive and can be easily confused with other illnesses, including COVID-19. This can make it more difficult to diagnose a patient who did not notice a rash or was unaware that they ever had a tick bite. As a result, Lyme disease cases can be <a href="http://doi.org/10.4081/or.2011.e14">misdiagnosed</a>. Nationally, Lyme disease may be undercounted to the point that only <a href="https://www.cdc.gov/lyme/datasurveillance/index.html">one in 10 cases is reported to the CDC</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/337494/original/file-20200526-106815-1090qjs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/337494/original/file-20200526-106815-1090qjs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/337494/original/file-20200526-106815-1090qjs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/337494/original/file-20200526-106815-1090qjs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/337494/original/file-20200526-106815-1090qjs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/337494/original/file-20200526-106815-1090qjs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/337494/original/file-20200526-106815-1090qjs.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">
<figcaption>
<span class="caption">A student plucks samples off a drag cloth used to collect ticks.</span>
<span class="attribution"><a class="source" href="https://biology.richmond.edu/research/research-labs/brinkerhoff-lab.html">Jory Brinkerhoff/University of Richmond</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>If Lyme disease is identified and treated quickly, <a href="https://www.cdc.gov/lyme/treatment/index.html">two to four weeks of antibiotics</a> can usually knock out <em>Borrelia burgdorferi</em>, the species of spirochete bacteria that causes it.</p>
<p>But delays in the treatment of Lyme disease <a href="http://doi.org/10.1038/nrdp.2016.90">can lead to more severe and persistent symptoms</a>. If Lyme disease goes untreated, <a href="https://www.columbia-lyme.org/signs-and-symptoms">neurological and cognitive problems</a> and <a href="https://www.healio.com/cardiology/practice-management/news/online/%7Bcb44ad64-eb7c-4ccd-b320-ac529225468a%7D/cardiologists-know-the-signs-of-lyme-disease">potentially fatal heart problems</a> can develop, and <a href="http://doi.org/10.1016/j.idc.2015.02.004">painful arthritis that is much more difficult to treat</a> can set in.</p>
<h2>Lyme disease isn’t the only tick problem</h2>
<p>Lyme disease is most common in the Northeast and North Central U.S., but that does not mean that people in areas without Lyme disease are free from worry about tick-transmitted disease. Ticks throughout North America can spread a <a href="https://www.cdc.gov/ticks/tickbornediseases/index.html">wide range of diseases,</a> many of which also present with flu-like symptoms, leading to the potential for <a href="https://doi.org/10.1016/j.ttbdis.2015.06.005">misdiagnosis</a>, especially when these diseases are not especially common in the general population.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/337504/original/file-20200526-106832-1gndpez.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/337504/original/file-20200526-106832-1gndpez.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/337504/original/file-20200526-106832-1gndpez.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/337504/original/file-20200526-106832-1gndpez.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/337504/original/file-20200526-106832-1gndpez.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/337504/original/file-20200526-106832-1gndpez.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/337504/original/file-20200526-106832-1gndpez.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">
<figcaption>
<span class="caption">A closeup of a tick’s head under an electron microscope.</span>
<span class="attribution"><a class="source" href="https://biology.richmond.edu/research/research-labs/brinkerhoff-lab.html">Fernando Otalora-Luna/University of Richmond</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Spotted fevers are <a href="https://www.cdc.gov/otherspottedfever/index.html">another group of tick-transmitted diseases</a>. The most severe of these is Rocky Mountain spotted fever, which can be fatal. Spotted fevers, as the name suggests, are typically associated with a rash. But the rash may not show until after fever and other flu-like symptoms, creating the same risk of being mistaken for COVID-19. Like Lyme disease, spotted fevers <a href="https://www.cdc.gov/otherspottedfever/treatment/index.html">can be treated with anitibiotics</a>, and early treatment can head off more severe infections, so quick, accurate diagnosis is critical. </p>
<h2>Is COVID-19 increasing chances of tick bites?</h2>
<p><a href="https://www.scientificamerican.com/article/how-the-coronavirus-has-changed-animals-landscape-of-fear/">Recent reports</a> from across the nation and around the globe suggest that wildlife have become more bold this spring, wandering into suburbs and cities where human and vehicle traffic are reduced because of COVID-19.</p>
<p>Whether this phenomenon is being driven by changes in animal behavior or is simply an artifact of humans spending <a href="https://www.popsci.com/story/environment/wildlife-in-cities-covid-shutdown/">more time in their homes and becoming more aware of their surroundings</a> is not clear, but changes in wildlife behavior and habitat use could affect tick-transmitted disease. For example, white-tailed deer are important hosts to multiple human-biting tick species in eastern North America, including black-legged ticks, and more deer around our homes and in our neighborhoods could lead to more ticks that have a chance to bite humans.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/337506/original/file-20200526-106811-vw1f8j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/337506/original/file-20200526-106811-vw1f8j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/337506/original/file-20200526-106811-vw1f8j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/337506/original/file-20200526-106811-vw1f8j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/337506/original/file-20200526-106811-vw1f8j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/337506/original/file-20200526-106811-vw1f8j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/337506/original/file-20200526-106811-vw1f8j.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">
<figcaption>
<span class="caption">A closeup of a tick’s mouth parts under an electron microscope shows the barbs that allow it to hang on after it penetrates skin.</span>
<span class="attribution"><a class="source" href="https://biology.richmond.edu/research/research-labs/brinkerhoff-lab.html">Fernando Otalora-Luna/University of Richmond</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Ticks do not move very far by themselves – <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1948-7134.2009.00034.x">perhaps about a foot per day for some species</a> – but can be dispersed dozens of miles or more while hitching a ride on a highly mobile host like a deer, coyote or bird. Thus, the wildlife we observe exploring our neighborhoods while we are encouraged to stay at home may be leaving behind ticks that are carrying pathogens, or that could acquire infection from the more common wildlife already near our homes.</p>
<h2>Staying safe</h2>
<p>Awareness is a key component of preventing and treating tick-borne disease. People should be aware of the activities that could <a href="https://www.cdc.gov/lyme/prev/index.html">expose them to ticks</a>, and <a href="https://pubmed.ncbi.nlm.nih.gov/10780095/">physicians should consider the possibility of tick-borne disease</a>, especially given the potential overlap in symptoms with COVID-19.</p>
<p>As with COVID-19, mitigation efforts can <a href="https://www.cdc.gov/lyme/prev/on_people.html">substantially reduce the risk</a> of tick-borne diseases. Wear long sleeves and long pants and use an <a href="https://www.epa.gov/insect-repellents">EPA-registered repellent</a> when you are in tick habitat, and check yourself thoroughly for ticks when you get home.</p>
<p>It is important to be aware of ticks when spending time outside, but fear of ticks should not stop people from enjoying nature.</p>
<p>[<em>Get facts about coronavirus and the latest research.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=upper-coronavirus-facts">Sign up for The Conversation’s newsletter.</a>]</p><img src="https://counter.theconversation.com/content/139104/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jory Brinkerhoff receives funding from the U.S. Department of Agriculture and the National Institutes of Health and has previously been funded by the Jeffress Memorial Trust and the Fulbright Scholar Program. </span></em></p>What might look like a mild case of COVID-19 could actually be a bacterial infection from a tick bite, with potentially debilitating symptoms if it goes untreated.Jory Brinkerhoff, Associate Professor of Biology, University of RichmondLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1334512020-03-18T14:32:25Z2020-03-18T14:32:25ZWhy the elimination of malaria needs much greater involvement of women<figure><img src="https://images.theconversation.com/files/320573/original/file-20200315-50583-18wx98r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Women are often primary caregivers in their communities.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>I was born and bred in the western part of Kenya, an area endemic of malaria. I have been sick from malaria not once, not twice, but more times than I can count. In my village, outbreaks were normal – the entire village would get sick, especially after the rains. I watched many people die, including classmates, relatives and even my own family members.</p>
<p>As a child, I watched mothers in my village work frantically to make sure their families were protected from the disease. They dressed the kids up to protect them from mosquito bites and cold weather. If someone contracted malaria, they would boil concoctions from traditional plants, cook finger millet (<em>wimbi</em>) porridge and ensure the patient would frequently shower to control fever. Sometimes they even carried the patient on their back to the hospital. When a family member was sick, the mother would practically be held hostage.</p>
<p>Unfortunately, the situation in my Kenyan village is not unique on this continent. Sub-Saharan Africa continues to carry an unreasonably high global burden of disease. <a href="https://www.who.int/news-room/feature-stories/detail/world-malaria-report-2019">In 2018</a>, the region was home to 93% of the world’s malaria cases. Most of the deaths (94%) were recorded in sub-Saharan Africa. Women bear the brunt of the disease, with children and pregnant women carrying the highest risk.</p>
<p>I am now a scientific researcher focused on malaria – partly because of my childhood experiences almost 30 years ago. I trap mosquitoes to <a href="https://malariajournal.biomedcentral.com/articles/10.1186/s12936-020-3108-0">monitor their behaviour</a>, and how they develop <a href="https://www.ncbi.nlm.nih.gov/pubmed/29304805">insecticide resistance</a>. I <a href="https://malariajournal.biomedcentral.com/articles/10.1186/s12936-019-3032-3">investigate</a> new insecticides we could use to counter mosquito resistance to the current chemicals. In villages across Kenya, I participate in the distribution of bed nets, spraying of houses with insecticides, conduct health education and screen for malaria infections.</p>
<p>I also participate in high-level meetings about controlling malaria and other vector-borne diseases in Kenya and beyond. Unfortunately, the number of women present in such meetings is low. This is a problem because women are primary caregivers and the key implementers of community-level interventions. But they are missing from top leadership or managerial positions. </p>
<p>If we’re serious about malaria elimination in Africa, women must be included at decision making levels to advise on development, designing, delivery and implementation of tools that target health issues that affect them – especially malaria.</p>
<h2>The role of women</h2>
<p>Women are clearly in charge in the villages I travel to for <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5838394/?">field work</a>. They implement the plans the men create in their faraway high-level meetings.</p>
<p>A 2016 report by the <a href="https://www.pamca.org/">Pan-African Mosquito Control Association</a> showed that very few women were part of workforces dealing with vector control. Last year the association convened a meeting in Cameroon of 29 women from 20 African countries to identify the gaps and challenges of addressing malaria and vector-borne diseases. Overall, there was an outcry that women were not considered for leadership positions, mostly due to African cultural norms in which they were viewed as the weaker sex. Even if they tried to step up, women reported being mostly ignored.</p>
<p>This is in direct contrast from my personal observations as a researcher. In communities, women ensure that high-quality bed nets are available and that everyone sleeps under them. If houses are sprayed with insecticides, women are the ones who ensure that the walls are not smeared or painted until the end of the shelf life of the chemical. Women also ensure that their children are treated in case of malaria infection and that they complete their doses.</p>
<p>Controlling malaria and other vector-borne diseases is complex. It needs integrated approaches and a range of voices. </p>
<h2>Way forward</h2>
<p>To harness its full potential, Africa must dismantle gender stereotypes. Incorporating women in the design, delivery and adoption of malaria interventions will enhance acceptance and compliance because women are the key implementers at community levels. And there should be concerted efforts to ensure they are part of policy making because they’re better equipped to build programmes with women in mind.</p>
<p>Excluding women -— particularly when making decisions on health issues that affect them, their children and the entire family — will continue to delay the realisation of malaria elimination on the continent. It will also be an impediment to economic development.</p><img src="https://counter.theconversation.com/content/133451/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Damaris Matoke-Muhia is a molecular biologist. She is a senior research officer at Kenya Medical Research Institute (KEMRI) and director of capacity building, gender mainstreaming & career progression at Pan-African Mosquito Control Association (PAMCA). She is a Fellow with the Aspen New Voices programme.</span></em></p>Women must be included at decision making levels to advise on development, designing, delivery and implementation of tools that target health issues that affect them especially malaria.Damaris Matoke-Muhia, Senior Research scientist, Kenya Medical Research InstituteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1050972018-10-22T10:41:48Z2018-10-22T10:41:48ZIs climate change causing a rise in the number of mosquito and tick-borne diseases?<figure><img src="https://images.theconversation.com/files/241473/original/file-20181019-105751-dgdmsr.jpg?ixlib=rb-1.1.0&rect=175%2C628%2C3589%2C1663&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Warmer temperatures could lead to more zones of the country that make good breeding sites for mosquitoes.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/mosquito-sucking-blood-on-human-skin-240718741">Apichart Meesri / Shutterstock.com</a></span></figcaption></figure><p>Life in a single-family home in suburban America, one with a quiet and spacious backyard, surrounded by natural habitats, lush green vegetation, where beautiful birds, squirrels and other small mammals come and go, is the American dream. Now, however, this once-cherished dream is being threatened by invading tick and mosquito species that are carrying emerging pathogens.</p>
<p>Public health officials use emerging vector-borne diseases (VBDs) in this context to refer to diseases or pathogenic agents transmitted by mosquitoes and ticks that have recently entered human populations for the first time. In some cases these diseases have historically been present in humans but have increased in frequency, geographic range or both. </p>
<p>Exposure to ticks and mosquitoes is the <a href="http://doi.org/10.1038/nature06536">single greatest risk factor for emerging vector borne diseases</a>, and the <a href="https://www.ncbi.nlm.nih.gov/pubmed/?term=PMC104807">introduction of these vectors to new geographic areas</a> has been a key contributing factor in the emergence of these diseases. Mounting evidence now suggests that climate change is facilitating the geographic expansion of mosquito and tick vectors of public health importance.</p>
<h2>New emerging vector-borne diseases in the US</h2>
<p>For more than half a century, outbreaks of dengue fever were not recorded in the continental United States. However, local infection has been recorded within the past decade in <a href="https://wwwnc.cdc.gov/eid/article/22/6/15-2000_article">Texas</a> and <a href="https://www.livescience.com/56304-dengue-case-in-florida.html">Florida</a>, a situation that has led to renewed interest in the <a href="https://www.ncbi.nlm.nih.gov/pubmed/23802440">threat posed by the mosquito vector <em>Aedes aegypti</em></a>. </p>
<p>In-depth studies of climate records over four decades reveal that sudden temperature changes were immediately followed by a <a href="http://doi.org/10.1016/j.vetpar.2009.09.011">corresponding increase in tick-borne encephalitis</a> in central and eastern Europe. The irregularly occurring <a href="https://www.climate.gov/enso">El Niño Southern Oscillation</a> which results from changes in air temperature over the Pacific Ocean that in turn cause changes in temperature and precipitation, has become a natural experiment for determining the effect of climate on infectious diseases. Previous studies of ENSO reveal that warmer temperatures and <a href="http://doi.org/10.1073/pnas.1604980113">extreme precipitation changes are associated with higher risk of tick-borne diseases</a> in the western United States. </p>
<p>This finding is particularly important, because climate change scenarios predict ENSO-like events to become more frequent. This is also exemplified by the <a href="http://doi.org/10.1016/S0140-6736(16)00256-7">recent global spread of Zika virus</a>, where extreme climatic conditions during one month in several parts of South America in 2015 were followed by the spread of Zika virus to that location the next month.</p>
<h2>Climate change and disease vectors</h2>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/241478/original/file-20181019-105748-8wgaz5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/241478/original/file-20181019-105748-8wgaz5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/241478/original/file-20181019-105748-8wgaz5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/241478/original/file-20181019-105748-8wgaz5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/241478/original/file-20181019-105748-8wgaz5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/241478/original/file-20181019-105748-8wgaz5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/241478/original/file-20181019-105748-8wgaz5.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">Child with microcephaly is seen in a clinic that cares for people affected by congenital Zika syndrome.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/child-microcephaly-seen-entity-that-cares-645211522?src=qu2BkNJHPYl8YL2TMHE2jw-1-49">Joa Souza / Shutterstock.com</a></span>
</figcaption>
</figure>
<p>In theory, <a href="http://doi.org/10.1098/rstb2001.0894">as the climate changes mosquito and tick vectors adapt to new environments</a>, which lead to shifts in the spatial distribution, seasonality and incidence rates of disease-carrying mosquitoes and ticks as they move to different regions.</p>
<p>Climate change can shape the rates of emerging disease by various processes including a direct effect on mosquito and tick vectors, and <a href="http://doi.org/10.1371/journal.pntd.0005568">indirect effects on human vulnerability to emerging VBDs</a>. For example, warmer temperatures lead to longer breeding seasons and greater hatch rates, especially for mosquito populations. This will cause these vectors to seek more territory, which is also more readily available from warmer temperatures. </p>
<p>The environments characteristic of most suburban residential properties are enticing habitat for these vectors, which might explain why more ticks and human infections with emerging VBDs are <a href="http://doi.org/10.3201/eid2105.150150">increasingly</a> <a href="http://doi.org/10.3201/eid2102.141276">reported</a> <a href="http://doi.org/10.1056/NEJM197010152831607">from</a> residential areas. </p>
<p>Indirect effects of warmer temperatures include <a href="http://doi.org/10.1098/rspb.2017.0901">weakening human immune systems</a> after droughts or flooding, and disruptions to the health care system following disasters such as hurricanes and floods. Many scientists consider this indirect mechanism, where exceptional climatic conditions affect people’s behavior and increase exposure to vectors, to explain much of how climate change affects the spread of emerging VBDs.</p>
<h2>A word of caution</h2>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/241476/original/file-20181019-105751-7udjti.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/241476/original/file-20181019-105751-7udjti.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/241476/original/file-20181019-105751-7udjti.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/241476/original/file-20181019-105751-7udjti.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/241476/original/file-20181019-105751-7udjti.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/241476/original/file-20181019-105751-7udjti.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/241476/original/file-20181019-105751-7udjti.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">
<figcaption>
<span class="caption">Ticks are present throughout the world, but they are especially fond of warm, humid climates.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/tick-sign-flower-meadow-background-196724855?src=hRQvcwh3SyMVOIe0YpVc2w-1-27">Schlegelfotos / Shutterstock.com</a></span>
</figcaption>
</figure>
<p>Although the evidence for associations between climate change and increased VBDs is strong, we should keep in mind that associations do not always indicate a causal link. In order to unequivocally attribute the changing distribution of mosquito and tick vectors of emerging VBDs to climate change, <a href="http://doi.org/10.1177/0141076814562718">scientific principles of causality must be established under randomized experimental conditions</a>. </p>
<p>For scientists to say definitively that climate change is directly boosting the population of disease-carrying mosquitoes and ticks, they would first need to demonstrate that the changes in distribution of these disease vectors were not due to other factors. </p>
<p>Why should we care about the association between climate change and the spread of emerging VBDs? For one, common bugs can transmit multiple pathogens. For example, the mosquito <em>Aedes aegypti</em> alone can spread <a href="https://theconversation.com/global-warming-to-expose-more-people-to-zika-spreading-mosquito-aedes-aegypti-58908">Zika virus</a>, dengue virus, chikungunya virus and yellow fever virus, while the tick <em>Ixodes scapularis</em> alone can transmit the causative agents of Lyme disease, anaplasmosis and babesiosis, among others. </p>
<p>Secondly, many of these diseases lead to increased health care costs, disability, and even death for affected individuals. </p>
<p>So far the current evidence suggests that while climate change is an important factor in the geographic and seasonal variation in mosquito- and tick-borne diseases, other factors including land-use patterns, socioeconomic and cultural factors, pest control, access to health care and human response to disease risk also play a role. </p>
<p>More rigorous long-term studies are needed to demonstrate unequivocally the impact of climate change on emerging VBDs of public health importance. If climate change increases the transmission of these diseases, we need to take all necessary steps to understand how this occurs with a view to preventing it. Otherwise, the American dream of home ownership in the suburbs is threatened, and climate change may soon be added to the long list of injustices and challenges that have undermined this American dream.</p><img src="https://counter.theconversation.com/content/105097/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Oghenekaro Omodior receives funding from Indiana University's Prepared for Environmental Change Grand Challenge Initiative. </span></em></p><p class="fine-print"><em><span>Daniel Becker receives funding from the Intelligence Community Postdoctoral Research Fellowship Program .</span></em></p>Is our changing climate making regions of the US more suitable for ticks and mosquitoes that spread diseases? Or is the climate changing human physiology making us more vulnerable?Oghenekaro Omodior, Assistant Professor of Recreation, Parks and Tourism, Indiana UniversityDaniel Becker, Postdoctoral Fellow, Indiana UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/970662018-06-18T10:40:53Z2018-06-18T10:40:53ZAs Venezuela’s public health system collapses, mosquito-borne viruses re-emerge<figure><img src="https://images.theconversation.com/files/222842/original/file-20180612-112605-1p8r8vw.jpg?ixlib=rb-1.1.0&rect=52%2C147%2C965%2C613&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Psorophora ferox female, a potential vector for Madariaga virus. Photo taken on Heritage Island, Anacostia River, in Washington, D.C., June 30, 2012.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/86548370@N00/7512088890">Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>The ability to predict which virus will cause the next epidemic is a science, an art and a gamble. We have learned through our work in Venezuela that it’s always a good idea to pay attention to the cryptic viruses. </p>
<p>During our work on the Zika virus epidemic in Venezuela, we may have spotted the emergence of a potentially dangerous virus that appears to be crossing from horses to humans: Madariaga virus. By using a diverse toolkit of approaches, we were able to look behind the curtains of the Zika virus epidemic to see what might be coming next. Time will tell if Madariaga virus will spread across Venezuela’s borders, but continued research will allow us to be prepared if it does.</p>
<p>As scientists, we aim to learn from past outbreaks and hope those lessons are applicable to future situations. We try to be proactive, because being caught unprepared and having to react to an outbreak comes at a cost that is often paid in human lives.</p>
<p>Being prepared includes keeping a close watch on human and animal viruses in circulation. This is referred to as <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4310698/">virus surveillance</a>. We pay attention to animal viruses because many of today’s deadly viruses such as <a href="http://www.who.int/news-room/fact-sheets/detail/ebola-virus-disease">Ebola virus</a> and <a href="https://www.cdc.gov/coronavirus/mers/index.html">Middle East respiratory syndrome coronavirus (MERS-CoV)</a> are animal viruses that now affect humans. Surveillance is especially important for mosquito-transmitted viruses, particularly when public health systems are overburdened and mosquito control is limited. </p>
<p>Moreover, <a href="http://jvi.asm.org/content/84/19/9733.full">viruses frequently mutate</a>, and it is important to track whether they are changing into more virulent versions. Billions of dollars and countless hours in the laboratory have been invested toward developing vaccines to protect humans and other animals such as horses and livestock against mosquito-transmitted viruses, but vaccines are not available for many of the important viruses.</p>
<p>We began working on mosquito-transmitted viruses during the 2016 outbreak of <a href="https://www.cdc.gov/zika/index.html">Zika virus</a> in Venezuela, along with Dr. J. Glenn Morris of the <a href="http://www.epi.ufl.edu/">Emerging Pathogens Institute</a> and with Dr. Alberto Paniz-Mondolfi, a physician based in Barquisimeto, Venezuela. We teamed up with the <a href="https://incubadorave.wordpress.com/">Incubadora Venezolana de la Ciencia</a>, a group of Venezuelan medical students, interns and physicians based in Barquisimeto. </p>
<p>As a native Venezuelan, G. Blohm had watched the country’s <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(16)00277-4/fulltext">public health system collapse</a> under the weight of an unprecedented economic crisis. She had watched hundreds of people leave the country. She, too, had left the country with a heavy heart after her family suffered repeated assaults and threats of kidnapping. She had seen better days in this beautiful place and has not stopped believing in the potential of its land and of its people. She knew that Venezuela’s crisis could affect neighboring countries and hoped to assist in monitoring the spread of mosquito-transmitted diseases within and across Venezuela’s borders. </p>
<p>Because the study of mosquito-transmitted diseases involves an element of chance, we could not have predicted what we would find. </p>
<h2>Viruses are often puzzling</h2>
<p>Mosquito-transmitted viruses can be deceiving. The illnesses they cause are often misdiagnosed or the virus is not detected. They can <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3134406/">hide behind similar early clinical symptoms</a>, yet there can be vast differences in long-term consequences to the patient. </p>
<p>This is true for <a href="https://www.cdc.gov/dengue/index.html">dengue</a>, <a href="https://www.cdc.gov/chikungunya/index.html">Chikungunya</a>, Zika and other mosquito-transmitted viruses, which can elicit similar symptoms during the early phase of infection in those affected, yet the long-term effects can vary significantly. It is therefore important to have the capacity to detect and identify these viruses in diagnostic laboratories. </p>
<p>In preparing for outbreaks of mosquito-transmitted viruses, it’s important also to understand the biology of each virus, its genetic makeup, proper methods for diagnosis and the clinical symptoms it can cause.</p>
<p>The genetic code of a virus contains information about its geographic origins and its relatedness to other viruses. Knowing its relatedness to other viruses can sometimes – but not always – give clinicians some clues about the symptoms it may cause. Uncovering the genetic code of a virus requires detection and isolation of the virus in the laboratory. </p>
<h2>How to detect a virus</h2>
<p>There are several ways to detect a virus: One can look for <a href="https://en.wikipedia.org/wiki/Antibody">antibodies</a> in the patient, or if the laboratory has the capacity and the timing is just right, one can actually retrieve (i.e., isolate) the virus from the patient. Some laboratory tests rely on antibodies to discern whether a patient has been infected with a particular virus in the past. </p>
<p>These tests, although common, are less precise and can be misleading: Antibodies to closely related viruses react against similar viruses. This cross-reactivity can confound diagnosis in countries wherein many of the viruses co-exist. </p>
<p><a href="https://www.intechopen.com/books/biomedical-tissue-culture/the-art-of-animal-cell-culture-for-virus-isolation">Isolation of a virus</a> is more precise, and it is as much a science as it is an art. The patient’s specimen needs to be collected properly, during the right time of infection, and the procedures used need to be just right for each type of virus. Ascertaining the correct procedures for isolating viruses requires years of training and experience. And the processes used require special equipment, instruments and facilities, making them impractical or impossible in resource-strapped laboratories.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/222883/original/file-20180612-112637-13o8aqh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/222883/original/file-20180612-112637-13o8aqh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/222883/original/file-20180612-112637-13o8aqh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/222883/original/file-20180612-112637-13o8aqh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/222883/original/file-20180612-112637-13o8aqh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/222883/original/file-20180612-112637-13o8aqh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/222883/original/file-20180612-112637-13o8aqh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The author preparing to work in the lab in Gainesville, Fla., June 12, 2018.</span>
<span class="attribution"><span class="source">Caroline Stephenson</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Viruses do not cause epidemics in a vacuum. In many cases, there are social and environmental conditions that set the stage for an outbreak. In Venezuela, the deterioration of the political and economic infrastructure, and the destruction of the country’s public health system have created conditions that make the inhabitants of this once prosperous country susceptible to outbreaks. Venezuela, which <a href="http://www.nationmaster.com/country-info/stats/Economy/GDP-per-capita-in-1950">in the 1950s was the world’s fourth wealthiest nation per capita</a>, currently has the <a href="https://www.forbes.com/sites/stevehanke/2018/04/25/the-ins-and-outs-of-venezuelas-hyperinflation-spotlights-on-the-imf-and-the-financial-press/#548a7f70103c">highest inflation rate in the world</a>.</p>
<p>Mosquito-transmitted diseases that were once under control such as Dengue Fever <a href="http://www.who.int/bulletin/volumes/85/10/07-011007/en/">have reached record high levels</a>, with no signs of receding. Other less well-known viruses are on the rise in Venezuela: some are inching their way across the barrier between domestic animals and humans. Madariaga virus (MADV) is one such virus which we suspect has crossed this barrier.</p>
<h2>Madariaga virus</h2>
<p>Madariaga virus is a South American virus that is genetically similar to <a href="https://www.cdc.gov/easternequineencephalitis/tech/symptoms.html">Eastern equine encephalitis virus</a> (EEEV). Scientists know much more about EEEV, which is a mosquito-transmitted virus that infects horses, humans and other animals. Although rare in humans, EEEV causes severe infections wherein up to <a href="https://www.cdc.gov/easternequineencephalitis/index.html">33 percent of those infected die</a>, usually due to encephalitis, or inflammation of the brain. Those that survive have significant brain damage. There is no vaccine to protect humans against EEEV or cure for the illnesses it causes. </p>
<p><a href="http://jvi.asm.org/content/84/2/1014">Recent genetic studies</a> reveal that MADV is distinct from but nevertheless closely related to EEEV, and is found in Central and South America. Antibody tests suggest the virus infects humans and caused an <a href="https://www.ncbi.nlm.nih.gov/pubmed/27101567">outbreak among Panamanians in 2010</a>, but until now, the virus itself only had been isolated from or detected in horses, rodents and mosquitos. </p>
<p>During our work on the Zika outbreak in Venezuela, we may have unveiled a more cryptic outbreak of MADV in humans. We <a href="https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciy224/4989405">detected the virus in the blood of a Venezuelan child</a> who had initially been thought to have Zika. The child had developed a fever, rash and joint pains, but his infection did not progress. And, he did not develop encephalitis. The child developed an infection at a time when veterinarians reported cases of neurologic disease among horses in the locality of the patient’s area of residence; the horses were thought to be infected with EEEV. Whereas laboratory confirmation of EEEV or MADV was not possible due to the situation in Venezuela, it is plausible that the horses were infected with MADV. The presence of the virus in this child, though, provides evidence that MADV infects humans. </p>
<p>We scientists have learned repeatedly that viruses like MADV and their mosquito vectors do not honor national borders, and that preventing their spread into surrounding areas requires international efforts. Preparedness and continued research will allow us to come out ahead of the next epidemic, which may very well have its origins in a country whose public health infrastructure is in disrepair. The entire global community needs continued research on the biology, the genetics and the clinical symptoms of MADV.</p><img src="https://counter.theconversation.com/content/97066/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gabriela Blohm receives funding from the National Science Foundation, the National Institutes of Health, and the Florida Department of Health. </span></em></p><p class="fine-print"><em><span>John A. Lednicky 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 collapse of Venezuela’s public health system has terrible consequences inside the country, but it also is giving rise to mosquito-borne viruses that could spread to nearby countries.Gabriela Blohm, Postdoctoral research associate, University of FloridaJohn A. Lednicky, Research Professor, Environmental and Global Health, University of FloridaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/961852018-05-25T10:47:27Z2018-05-25T10:47:27ZSelf-cloning Asian tick causing worry in New Jersey<figure><img src="https://images.theconversation.com/files/220197/original/file-20180523-88002-r4bohx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The female longhorned tick, _Haemaphysalis longicornis_, crawling on a leaf.</span> <span class="attribution"><span class="source">Jim Occi, Rutgers Center for Vector Biology</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>New Jersey has a new visitor, and it’s not welcome.</p>
<p>No one is quite sure how the longhorned tick <em>Haemaphysalis longicornis</em>, an invasive bug originally from East Asia arrived in New Jersey and where, exactly, it came from. But what is clear is that this new tick is capable of surviving winters in the state and is now establishing a stable population. That is bad news for both animals and people because this arthropod can bite them and transmit disease.</p>
<p>This is not the first time this species has found its way to new habitats. Over the last century, the tick has colonized Australia and New Zealand, along with other Pacific islands.</p>
<p>One of the traits that makes this tick such an invasive pest is that it is a parthenogenetic species, which means it does not need males to reproduce. Just one female tick is enough to establish a new clonal population that is genetically identical to its mother. In fact, <a href="https://www.ncbi.nlm.nih.gov/pubmed/5757695">clonal populations are present in Australia, New Zealand and Asia.</a></p>
<p>The tick was <a href="https://doi.org/10.1093/jme/tjy006">first discovered feeding on a single sheep</a> in a farm in Hunterdon County, New Jersey, in August 2017. The tick was identified by the Center for Vector Biology at Rutgers University and the Hunterdon County Department of Health, and later confirmed by the National Veterinary Services Laboratory.</p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/219822/original/file-20180521-14970-1ebd8u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/219822/original/file-20180521-14970-1ebd8u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219822/original/file-20180521-14970-1ebd8u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219822/original/file-20180521-14970-1ebd8u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219822/original/file-20180521-14970-1ebd8u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219822/original/file-20180521-14970-1ebd8u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219822/original/file-20180521-14970-1ebd8u.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">A tick-infested shoreline of Long Island, New York.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/sign-warning-tick-infested-area-on-441689995?src=XXfjeTmM1BO1UG0MQNHa5w-1-13">By Elzbieta Sekowska/shutterstock.com</a></span>
</figcaption>
</figure>
<h2>Tough survivor</h2>
<p><a href="https://doi.org/10.1093/jme/tjy006">Despite treating the sheep and surrounding fields</a> with the pesticide permethrin in late September to contain the infestation, <em>H. longicornis</em> survived the winter and reappeared in the spring. Surveillance efforts by our team confirmed the tick was present in Union County earlier this year, and that the New Jersey population is clonal. This underscores the invasive nature of this new pest and the challenges we face trying to control it.</p>
<p>Similar to deer ticks, the immature larvae and nymphs of the longhorned tick are very small, similar to a poppy and sesame seed respectively, and are easily over looked on both animals and people. In Asia, the longhorned tick feeds preferentially on livestock and wild animals like deer, bear and foxes, among others. Though less frequent, <em>H. longicornis</em> also bites pets such as cats and dogs, as well as people.</p>
<h2>Spreading fatal diseases</h2>
<p>Epidemics of vector-borne pathogens have <a href="https://doi.org/10.17226/11950">risen dramatically in recent years</a>, as we have witnessed the introduction of Zika and West Nile viruses in the U.S., Crimean-Congo hemorrhagic fever in Southwestern Europe, and the continuous emergence of Lyme disease throughout the Northeast of the U.S. and central Europe. Ticks are the most important vectors for infectious diseases in the Northern Hemisphere and second worldwide, after mosquitoes. Thus, the introduction of an invasive species in a new habitat is worrying.</p>
<p>In Asia and Australia, the longhorned tick is known to transmit diseases to livestock including protozoans <em>Theileria orientalis</em> and <em>Babesia</em> spp., which cause anemia, lethargy and occasionally abortions. In addition, uninfected longhorned ticks can endanger the animal’s health since in large numbers their constant blood-sucking causes anemia, loss of productivity, and occasionally the death of calves.</p>
<p>In addition, <em>H. longicornis</em> has been associated with human pathogens including <em><a href="http://doi.org/10.1371/journal.pone.0078189">Anaplasma phagocytophilum</a></em>, <a href="http://doi.org/10.1645/GE-2751.1">spotted fever</a> <em><a href="https://doi.org/10.1292/jvms.10-0369">Rickettsia</a></em>, and <em><a href="http://doi.org/10.3201/eid2405.171355">Borrelia</a></em> <a href="http://doi.org/10.4142/jvs.2016.17.2.207">spp</a>. These ticks also carry viruses, including <a href="https://www.ncbi.nlm.nih.gov/pubmed/?term=Genetic+characterisation+of+Powassan+virus+(POWV)+isolated+from+Haemophysalis+longicornis+ticks+in+Primorye+and+two+strains+of+Tick-borne+encephalitis+virus+(TBEV)+(Flaviviridae%2C+Flavivirus)%3A+Alma-Arasan+virus+(AAV)+isolated+from+Ixodes+persulcatus+ticks+in+Kazakhstan+and+Malyshevo+virus+isolated+from+Aedes+vexans+nipponii+mosquitoes+in+Khabarovsk+kray">Powassan virus</a>, which has a high fatality rate of up to 10 percent. Of those who survive, 50 percent experience permanent brain injury and <a href="http://doi.org/10.1089/vbz.2015.1832">SFTS virus</a> (severe fever with <a href="http://doi.org/10.3201/eid2405.151435">thrombocytopenia syndrome</a>), which causes encephalitis and severe fever with thrombocytopenia, a shortage of blood clotting platelets. Although tick-borne pathogens are generally tick specific, the fact that this tick has been associated with <em>Anaplasma phagocytophilum</em> and Powassan virus, which are present in New Jersey, raises the question of whether they can acquire and transmit these diseases locally.</p>
<p>So far, there are no documented instances of <em>H. longicornis</em> transmitting human pathogens, and there is no evidence so far that they represent a public health risk. </p>
<h2>No new controls in sight</h2>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/219820/original/file-20180521-14991-16qkxn7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/219820/original/file-20180521-14991-16qkxn7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219820/original/file-20180521-14991-16qkxn7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219820/original/file-20180521-14991-16qkxn7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219820/original/file-20180521-14991-16qkxn7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219820/original/file-20180521-14991-16qkxn7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219820/original/file-20180521-14991-16qkxn7.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">Insect repellent is the best protection against ticks.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/middle-age-woman-applying-insect-repellent-1021909885?src=ao9oEy0o7QH-gIUoXOHe3Q-1-0">By MNStudio/shutterstock.com</a></span>
</figcaption>
</figure>
<p>Although an invasive tick like the longhorned tick should be controlled and eradicated when possible, New Jersey already has a tick problem – and so this newcomer tick is not a cause for more alarm. We have four tick species that often bite humans including the deer tick <em>Ixodes scapularis</em>, the lone star tick <em>Amblyomma americanum</em>, the American dog tick <em>Dermacentor variabilis</em> and the brown dog tick <em>Rhipicephalus sanguineous</em>. They transmit diseases including Lyme disease, human anaplasmosis, human ehrlichiosis, human babesiosis, Rocky Mountain spotted fever and Powassan encephalitis.</p>
<p>Unfortunately, ticks are extremely hard to control and efforts to develop new control methods have always fallen short. The best way to protect ourselves is by using tick repellents and checking ourselves for attached ticks after any outdoor activity.</p><img src="https://counter.theconversation.com/content/96185/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alvaro Toledo receives funding from NIAID </span></em></p>There is a new type of tick spreading in New Jersey, and it doesn’t need a male to reproduce. It’s known to spread disease and is proving
difficult to eradicate.Alvaro Toledo, Assistant Professor of Entomology, Rutgers UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/966882018-05-21T10:45:25Z2018-05-21T10:45:25ZTicks and mosquitoes bringing more diseases – what can we do?<figure><img src="https://images.theconversation.com/files/219593/original/file-20180518-42220-1w0agca.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A female deer tick on a piece of straw. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/close-photo-adult-female-deer-tick-342282746?src=G3L6_jMyg7rlKsjzxdYGuQ-1-44">Steve Ellingson/Shutterstock.com</a></span></figcaption></figure><p>Cases of <a href="https://www.cdc.gov/ncezid/dvbd/index.html">vector-borne disease</a> have <a href="https://www.cdc.gov/mmwr/volumes/67/wr/mm6717e1.htm?s_cid=mm6717e1_w">more than doubled</a> in the U.S. since 2004, the Centers for Disease Control and Prevention recently reported, with mosquitoes and ticks bearing most of the blame.</p>
<p>Mosquitoes, long spreaders of malaria and yellow fever, have more recently spread dengue, Zika and Chikungunya viruses, and caused epidemic outbreaks, <a href="https://www.cdc.gov/zika/geo/index.html">mainly in U.S. territories</a>. The insects are also largely responsible for making <a href="https://www.cdc.gov/westnile/index.html">West Nile virus</a> endemic in the continental U.S. </p>
<p>Ticks, which are not insects but <a href="http://ento.psu.edu/extension/factsheets/ticks">parasitic arthropods</a>, actually cause more disease in the U.S. than mosquitoes do, accounting for <a href="https://www.cdc.gov/mmwr/volumes/67/wr/mm6717e1.htm?s_cid=mm6717e1_w">76.51 percent of total U.S. vector-borne disease cases</a>. These include Lyme disease and Rocky Mountain spotted fever and newer diseases as well. </p>
<p>Why the uptick in vector-borne disease, and more importantly, how can we protect ourselves from potentially serious diseases? As researchers of these types of diseases, we have some answers. </p>
<h2>Blood: The high cost of living</h2>
<p>Both mosquitoes and ticks transmit disease-causing pathogens through bites.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/219261/original/file-20180516-155579-es58gg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/219261/original/file-20180516-155579-es58gg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219261/original/file-20180516-155579-es58gg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219261/original/file-20180516-155579-es58gg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219261/original/file-20180516-155579-es58gg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219261/original/file-20180516-155579-es58gg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219261/original/file-20180516-155579-es58gg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Shelley Whitehead</span></span>
</figcaption>
</figure>
<p>Only the female mosquito takes a blood meal to make eggs, but almost all life stages of ticks need blood to survive.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/219264/original/file-20180516-155584-1b2e2gz.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/219264/original/file-20180516-155584-1b2e2gz.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219264/original/file-20180516-155584-1b2e2gz.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219264/original/file-20180516-155584-1b2e2gz.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219264/original/file-20180516-155584-1b2e2gz.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219264/original/file-20180516-155584-1b2e2gz.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219264/original/file-20180516-155584-1b2e2gz.jpeg?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">
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Joyce Sakamoto</span></span>
</figcaption>
</figure>
<p>Although mosquitoes were first demonstrated to have the ability to transmit diseases <a href="https://wwwnc.cdc.gov/eid/article/24/5/pdfs/17-1609.pdf">in 1889</a>, mosquitoes have been transmitting diseases for far longer. Written records as early as 2700 B.C. suggest <a href="https://parasitesandvectors.biomedcentral.com/track/pdf/10.1186/1756-3305-3-5">malaria plagued humans in China</a>.</p>
<p>The first suspected dengue outbreak occurred in the early 1600s, but it took three centuries for the first three mosquito-borne diseases – malaria, dengue and yellow fever – to invade the Americas. Yet, in the past two decades alone, we’ve experienced a wave of <a href="https://www.cdc.gov/zika/reporting/case-counts.html">three more mosquito-borne diseases</a> – <a href="https://link.springer.com/content/pdf/10.1007%2Fs40475-013-0008-1.pdf">West Nile, Chikungunya and Zika viruses</a>. This marked increase in disease spread is due to several factors, including advances in air and water travel and <a href="https://theconversation.com/global-warming-to-expose-more-people-to-zika-spreading-mosquito-aedes-aegypti-58908">warming temperatures</a>. </p>
<h2>The high cost of international travel and trade</h2>
<p>The international tire trade has made <em>Aedes albopictus</em>, the Asian tiger mosquito, a global traveler. This mosquito gains passage on <a href="https://www.npr.org/programs/atc/features/2001/mar/010309.disease.html">cargo ships</a> and gets unlimited access to man-made containers, which it needs for breeding, in the thousands of tires on board these ships. Rainwater collecting in the tires are ideal breeding sites. Even though it is not a major vector of dengue, Chikungunya and Zika viruses, this invasive species is still especially dangerous. It is able to outcompete most other mosquito species that live in similar habitats. </p>
<p>We humans serve as hosts for many vector-borne diseases, and our own movement can aid transmission. We can hop on a plane and be in a different country within hours. Diseases once quarantined to other regions of the globe can now be easily transported within an infected human. Some people don’t even realize they are sick. Researchers have estimated that up to 80 percent of individuals infected with Zika virus are <a href="https://www.nature.com/articles/s41598-017-05013-9.pdf">symptomless</a>. Yet, if the right vector feeds on a symptomless but infected person, transmission can still occur. </p>
<p>Increased <a href="https://academic.oup.com/femsle/article/364/19/fnx186/4107775">climate fluctuations</a>, largely due to human activity, can also affect how vector-borne diseases spread. Warmer climates may allow mosquitoes to survive in areas previously too cold to support them.</p>
<p>Predicting the outcome of warming on overall vector populations can be difficult. If, for example, summer in the deep Southeast becomes too hot and dry for mosquito development, peaks in transmission and mosquito numbers could shift to the fall. Higher temperatures may shorten the time it takes for pathogens to develop within mosquitoes, so mosquitoes may become <a href="http://www.pnas.org/content/pnas/106/33/13844.full.pdf">infectious faster</a> and transmit pathogens sooner. </p>
<h2>Tick-borne diseases</h2>
<p><a href="https://www.cell.com/trends/parasitology/fulltext/S1471-4922(12)00121-3?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS1471492212001213%3Fshowall%3Dtrue">Five percent of 900 tick species</a> are known to transmit disease-causing microorganisms. Because <a href="https://doi.org/10.1007/978-94-007-7497-1">38 percent of all tick species</a> have been known to bite humans, researchers will likely find more tick-borne diseases. Since 2004, there have been nine new vector-borne diseases described in the U.S., and seven of these are tick-transmitted, including the two potentially fatal Bourbon and Heartland viruses. </p>
<p>Most, or <a href="https://www.cdc.gov/mmwr/volumes/67/wr/mm6717e1.htm?s_cid=mm6717e1_w">82 percent</a> of tick-borne disease cases, are Lyme disease, which is caused by the bacteria <em>Borrelia burgdorferi</em>, and transmitted by the blacklegged, or deer, tick. <a href="https://doi.org/10.15585/mmwr.mm6717e1">Cases</a> of Lyme, Rocky Mountain spotted fever, babesiosis, anaplasmosis and ehrlichiosis have increased two-and-a-half to six-and-a-half fold.</p>
<p>Tick-borne diseases may be rising due to global travel, animal transport, habitat fragmentation and changing climate. <a href="https://doi.org/10.3390/ijerph15030478">Climate change</a> is correlated with range expansion of several important tick species. Ticks previously limited by cold winters are now becoming established farther north. In response to the arrival of Lyme disease to Canadian soil, the Public Health Agency of Canada responded with a <a href="https://www.canada.ca/en/public-health/services/publications/diseases-conditions/lyme-disease-canada-federal-framework.html">Federal Framework on Lyme Disease</a> focused on disease surveillance, education and awareness, and best practices for control, prevention and treatment of Lyme disease.</p>
<h2>What can you do?</h2>
<p>To lower your risk of transmission from mosquitoes: </p>
<ul>
<li><p>Check backyards for anything that could hold water and empty such vessels. This includes children’s toys, bird baths, empty soda cans and flower pots.</p></li>
<li><p>Use mosquito repellents that are <a href="https://www.epa.gov/insect-repellents">EPA</a> approved. Avoid natural repellents that haven’t been verified for their effectiveness. </p></li>
</ul>
<p>To prevent tick bites: </p>
<p>One sure way to prevent tick bites is to avoid suitable habitats for ticks, but this isn’t always possible. Large-scale habitat control or acaricide (tick-killing) treatment of wildlife, though possible, can be difficult or not cost-effective for homeowners. The best preventative measures are:</p>
<ul>
<li><p>Use CDC-recommended repellents such as DEET or picaridin. </p></li>
<li><p>Shower and do a thorough tick check.</p></li>
</ul>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/219319/original/file-20180517-155573-f3ou6q.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/219319/original/file-20180517-155573-f3ou6q.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219319/original/file-20180517-155573-f3ou6q.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219319/original/file-20180517-155573-f3ou6q.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219319/original/file-20180517-155573-f3ou6q.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219319/original/file-20180517-155573-f3ou6q.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219319/original/file-20180517-155573-f3ou6q.jpeg?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">
<figcaption>
<span class="caption">Tick check.</span>
<span class="attribution"><span class="source">Joyce Sakamoto</span></span>
</figcaption>
</figure>
<p>Tick checks are absolutely crucial. People usually follow this routine after going outdoors, but sometimes forget. And, they often avoid places that ticks love, such as between your legs. Hard-to-reach areas are prime real estate for blood-feeding parasites that don’t want to be dislodged, so make sure to check: the hairline (especially on children), torso, belly button and groin. If necessary, get assistance or a mirror and a bright light. </p>
<p>If you find an embedded tick, <a href="https://www.cdc.gov/ticks/removing_a_tick.html">correctly dislodge it</a> with fine-tipped tweezers, grasping the part closest to the skin and pulling straight up. Do not burn, squeeze, twist or smother the tick, since this may cause it to regurgitate. Gross-out alert: Any pathogens they have in their saliva can then be dumped into the bite site. </p>
<p>After removal, keep the tick for identification; different species transmit different pathogens. Finally, see a doctor after finding an embedded tick or if you think you have been bitten. In addition to getting medical attention, your data will be added to the national list of reported tick-borne diseases. </p>
<p>The CDC has several pages dedicated to vector-borne disease control and prevention. Local state health departments, general practitioners and veterinarians will also have recommendations for prevention, treatment and vector control. Talk to your veterinarian about repellents or agents that will kill mites called <a href="https://www.medicinenet.com/script/main/art.asp?articlekey=25533">acaricides</a> for pets, since some can be toxic to cats.</p><img src="https://counter.theconversation.com/content/96688/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Joyce Sakamoto receives funding from NSF. </span></em></p><p class="fine-print"><em><span>Shelley Whitehead receives funding from NIH NIAID. </span></em></p>The CDC recently announced an uptick in diseases spread by vectors such as mosquitoes and ticks. Here’s why and what you can do to lower your risk.Joyce Sakamoto, Assistant Research Professor of Entomology, Penn StateShelley Whitehead, Doctoral Candidate, Entomology, Penn StateLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/775412017-05-23T03:48:21Z2017-05-23T03:48:21ZInfecting mosquitoes with bacteria so they can’t infect us with viruses like Zika and dengue<figure><img src="https://images.theconversation.com/files/170203/original/file-20170519-12250-7w6chd.jpg?ixlib=rb-1.1.0&rect=267%2C0%2C3640%2C2450&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Tiny bug, major disease spreader.</span> <span class="attribution"><a class="source" href="https://pixnio.com/science/microscopy-images/insects/anopheles-gambiae-mosquito/of-the-approximately-430-anopheles-species-only-30-40-transmit-malaria-in-nature">Dr. Paul Howell, USCDCP</a></span></figcaption></figure><p>Mosquitoes and their itchy bites are more than just an annoyance. They transmit dangerous viruses with deadly consequences – making them the <a href="https://www.gatesnotes.com/Health/Most-Lethal-Animal-Mosquito-Week">most lethal animal on Earth</a>. It’s the <em>Aedes aegypti</em> and <em>Aedes albopictus</em> mosquito species that are behind outbreaks of <a href="https://www.cdc.gov/dengue/">dengue virus</a>, <a href="https://www.cdc.gov/zika/">Zika virus</a>, <a href="https://www.cdc.gov/yellowfever/">yellow fever virus</a> and <a href="https://www.cdc.gov/chikungunya/index.html">Chikungunya virus</a>, responsible for over <a href="https://www.cdc.gov/ncezid/dvbd/">100 million human cases</a> around the world annually. And they’re <a href="https://dx.doi.org/10.7554/eLife.08347">expanding their habitat</a> around the world as the <a href="https://doi.org/10.1371/journal.pone.0060874">global climate warms</a>, bringing them into contact with more potential victims who have <a href="https://doi.org/10.1128/JVI.00252-16">less immunity and increased susceptibility</a> to these mosquito-transmitted viruses.</p>
<p>A vaccine can provide the recipient with immunity to one or two of these viruses at a time. But there’s another way to tackle these diseases: by going after the insects. Targeting the mosquito population as a whole or their ability to transmit disease takes aim at all these viruses at the same time.</p>
<p>As the U.S. enters another mosquito season, mosquito control districts in <a href="http://keysmosquito.org/2017/03/03/fkmcd-to-test-wolbachia-mosquitoes-in-mid-april/">Florida</a> and <a href="https://cmad.maps.arcgis.com/apps/MapJournal/index.html?appid=f90115bcf15943928fc82a79af89d71e">California</a> are preparing <a href="http://www.cnn.com/2017/04/20/health/florida-mosquito-wolbachia-trial-zika/">new strategies to combat mosquitoes</a> and the viruses they transmit. They’re trying out one of two new mosquito management methods made possible by a bacterium called <em>Wolbachia pipientis</em>. </p>
<h2>A bacterium that’s our enemy’s enemy</h2>
<p><em>Wolbachia</em> are bacteria naturally found in insects throughout the world. They live inside a host organism’s cells. From there, <em>Wolbachia</em> are able to manipulate their host in many ways – things like <a href="https://doi.org/10.1126/science.1209609">increasing the number of eggs</a> a host lays or even <a href="https://doi.org/10.1038/nrmicro1969">changing the host’s sex</a> from male to female by manipulating its hormones.</p>
<p>Researchers discovered in 2008 that <em>Wolbachia</em> in fruit flies <a href="https://dx.doi.org/10.1126/science.1162418">protect their hosts from fruit fly viruses</a>. That realization got them wondering: Could <em>Wolbachia</em> also protect <em>Aedes aegypti</em> mosquitoes from viruses that cause human diseases?</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/170430/original/file-20170522-7361-cycavo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/170430/original/file-20170522-7361-cycavo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/170430/original/file-20170522-7361-cycavo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/170430/original/file-20170522-7361-cycavo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/170430/original/file-20170522-7361-cycavo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/170430/original/file-20170522-7361-cycavo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/170430/original/file-20170522-7361-cycavo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/170430/original/file-20170522-7361-cycavo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&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>Wolbachia</em> bacteria, indicated in red, are distributed throughout the infected mosquitoes.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/pennstatelive/12589512185">Penn State</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
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</figure>
<p><em>Aedes aegypti</em> mosquitoes don’t naturally carry <em>Wolbachia</em>. But consistent with the fruit fly studies, when researchers infected <em>Aedes aegypti</em> in the lab, the viruses they carry <a href="http://dx.doi.org/10.1016/j.cell.2009.11.042">replicated less</a>. Fewer of the infectious bits of the disease-carrying virus inside the mosquito meant disease transmission was limited – they were less likely to be passed on when mosquitoes fed on their prey.</p>
<p>Researchers in <a href="http://vectorbiologygroup.com/">Australia</a>, the <a href="http://people.bu.edu/hfrydman/">United States</a> and elsewhere are currently investigating the reasons why <em>Wolbachia</em> limit viruses. Some hypothesize <em>Wolbachia</em> improves the <a href="https://doi.org/10.1371/journal.ppat.1002548">mosquitoes’ immunity to the virus</a>, while other research, including my own, suggests <em>Wolbachia</em> <a href="https://doi.org/10.1128/JVI.00339-17">steals key nutrients</a> the virus needs. Both may be true.</p>
<p>The real need to employ this strategy now is motivating field trials to release <em>Wolbachia</em>-infected mosquitoes in several regions of the world. </p>
<h2>Vector competency: The female approach</h2>
<p>Only female mosquitoes bite and transmit viruses. Thus, the most powerful approach to reducing virus spread is limiting viruses in the female mosquito.</p>
<p><em>Wolbachia</em> bacteria are transmitted from mother to offspring. If you introduce <em>Wolbachia</em>-infected female mosquitoes to a population, all offspring will have <em>Wolbachia</em> – and therefore be less likely to transmit disease-causing viruses.</p>
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<a href="https://images.theconversation.com/files/170427/original/file-20170522-7372-1d6t4ca.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/170427/original/file-20170522-7372-1d6t4ca.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/170427/original/file-20170522-7372-1d6t4ca.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/170427/original/file-20170522-7372-1d6t4ca.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/170427/original/file-20170522-7372-1d6t4ca.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/170427/original/file-20170522-7372-1d6t4ca.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/170427/original/file-20170522-7372-1d6t4ca.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/170427/original/file-20170522-7372-1d6t4ca.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">Researchers in Vietnam working with <em>Wolbachia</em>-infected mosquito pupae.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Vietnam-Dengue-Blocking-Mosquito/199b148f9cf54dfa822d6ff0e6ff119f/14/0">AP Photo/Na Son Nguyen</a></span>
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</figure>
<p>This strategy is used by the <a href="http://www.eliminatedengue.com/program">Eliminate Dengue</a> program, a nonprofit collaboration employing seven research institutes around the world. In test areas, Eliminate Dengue has successfully incorporated <em>Wolbachia</em> into mosquito populations.</p>
<p>In this context, an interesting aspect of <em>Aedes aegypti</em> behavior is their tendency not to travel far. In fact, a highway is a sufficient barrier to <a href="https://doi.org/10.1371/journal.pntd.0000634">prevent mosquito spread</a>. When researchers set up a release site in one city or town, they don’t see their mosquitoes travel to other areas.</p>
<p>This allows for controlled studies, as well as the release of these mosquitoes only where it’s been approved. The limited spread and isolated sites used were important factors in the <a href="https://www.epa.gov/pesticides/epa-grants-extension-experimental-use-permit-wolbachia-mosquito">decision to allow mosquito releases in the United States</a>.</p>
<p>Eliminate Dengue is not yet active in the U.S. Instead, the U.S. is taking a different approach, looking to male rather than female mosquitoes.</p>
<h2>Population control: The male approach</h2>
<p><a href="http://mosquitomate.com/?v=3.0">MosquitoMate</a> is a company developed out of the University of Kentucky in Lexington by medical entomologist Stephen Dobson. Partnering with the <a href="http://keysmosquito.org/">Florida Keys Mosquito Control District</a>, they started the <a href="http://keysmosquito.org/2017/04/18/fkmcd-releases-wolbachia-mosquitoes-on-stock-island/">release of 40,000 <em>Wolbachia</em>-infected</a> <a href="http://fkmcd.maps.arcgis.com/apps/MapJournal/index.html?appid=d8c2b636e93b40b4b940e6042ef286c6">male mosquitoes per week this spring</a>.</p>
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<a href="https://images.theconversation.com/files/170426/original/file-20170522-7358-lhsm36.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/170426/original/file-20170522-7358-lhsm36.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/170426/original/file-20170522-7358-lhsm36.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/170426/original/file-20170522-7358-lhsm36.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/170426/original/file-20170522-7358-lhsm36.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/170426/original/file-20170522-7358-lhsm36.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/170426/original/file-20170522-7358-lhsm36.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/170426/original/file-20170522-7358-lhsm36.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&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 Florida Keys Mosquito Control District research entomologist releasing <em>Wolbachia</em>-infected male mosquitoes in Key West, Florida, in April.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Modified-Mosquitoes/0ef1eb60fb234e628c7ce2c3fe5a9522/1/0">Beth Ranson/Florida Keys Mosquito Control District via AP</a></span>
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<p>The strategy relies on a phenomenon called <a href="https://doi.org/10.1073/pnas.0403853101">cytoplasmic incompatibility (CI)</a> to reduce mosquito populations. CI occurs when a male mosquito infected with <em>Wolbachia</em> mates with an uninfected female. Because <em>Wolbachia</em> is transmitted through the female egg, the offspring will be <em>Wolbachia</em>-free. But <em>Wolbachia</em> has already altered the father’s sperm DNA in a way that allows offspring to survive only if the fertilized egg has <em>Wolbachia</em>. Since the infected males will come in contact only with the naturally occurring <em>Wolbachia</em>-free population, their offspring will die during embryonic development – the eggs won’t hatch. </p>
<p>And unfortunately for the mosquitoes, females store sperm inside them to continuously fertilize their eggs. This means that the female mosquito’s first mate will be the father of all her offspring. So even if a female just mates again, once she’s partnered with a <em>Wolbachia</em>-infected male, all her offspring will not be viable.</p>
<p>The Florida Keys Mosquito District is not limiting its attack to <a href="http://keysmosquito.org/control-methods/">just one approach</a>. Beyond <em>Wolbachia</em> and more traditional strategies, they’re also partnering with <a href="http://www.oxitec.com">Oxitec</a>, a genetic engineering company. Like MosquitoMate, Oxitec also releases male mosquitoes. But, in place of <em>Wolbachia</em>, Oxitec genetically modifies its mosquito to <a href="http://www.oxitec.com/our-solution/technology/">contain a self-limiting gene that causes offspring to die</a>.</p>
<p>The goal remains the same: Release males into the environment that will mate with females and cause all offspring to die, eventually leading to a mosquito population crash.</p>
<h2>Male and female strategies share one goal</h2>
<p>Each <em>Wolbachia</em> mosquito strategy has its strengths: The female approach is broad-reaching and should directly decrease disease transmission. The male strategy effectively lowers the local mosquito population, without releasing female nuisance mosquitoes.</p>
<p>The male release strategies are an important “right-now” fix, but they’ll require an annual, costly release because male mosquitoes – with either MosquitoMate’s <em>Wolbachia</em> or Oxitec’s self-limiting gene – cannot pass on to the next generation their crucial trait. When these males are not being released, fertile wild males will mate with females and the population will rebound.</p>
<p>Eliminate Dengue’s female release strategy is sustainable long-term, but it takes extensive monitoring to ensure the initial establishment of mosquitoes. While MosquitoMate and Oxitec do not disclose their costs, Eliminate Dengue hopes to make their system affordable at a cost of <a href="https://dx.doi.org/10.1038/533450a">approximately US$1 per person</a>.</p>
<p>Some members of the public have <a href="https://dx.doi.org/10.1126/science.aal0350">advocated against these kinds of mosquito release programs</a>, particularly when the mosquitoes have been genetically modified, as with Oxitec’s transgenic insects. While the United States Department of Agriculture received <a href="https://dx.doi.org/10.1038/533450a">2,600 responses to the Oxitec plan, only one response</a> was filed regarding MosquitoMate’s non-GMO strategy.</p>
<p>In the U.S., mosquito control districts are taking a cautious approach. They’re first trying the two nonpermanent male strategies in small areas. The Florida Keys will be <a href="http://keysmosquito.org/2017/03/03/fkmcd-to-test-wolbachia-mosquitoes-in-mid-april/">evaluating mosquitoes on their Stock Island release site for 12 weeks</a>. We should know how effective male <em>Wolbachia</em>-infected mosquitoes are at reducing populations by late summer.</p><img src="https://counter.theconversation.com/content/77541/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michaela Schultz 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>Several sites in the US are releasing bacteria-infected mosquitoes as a way to fight mosquito-borne viruses that threaten people. What’s the science – and how well will it work?Michaela Schultz, Graduate Student in Biology, Boston UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/765562017-04-24T23:24:03Z2017-04-24T23:24:03ZWhy cuts in funding for UN, climate change research imperil fight against malaria<figure><img src="https://images.theconversation.com/files/166571/original/file-20170424-12645-2f0a64.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mosquitoes could expand their reach if money for climate change research is cut. </span> <span class="attribution"><span class="source">Centers for Disease Control. </span></span></figcaption></figure><p>Diseases don’t stop at borders. On <a href="http://www.rollbackmalaria.org/calendar-of-events/world-malaria-day">World Malaria Day</a>, this is especially important to understand and to consider. </p>
<p>We’ve been fighting malaria for decades, and yet it still claimed nearly <a href="http://www.who.int/malaria/publications/world-malaria-report-2016/report/en/">half a million lives</a> in 2015. <a href="http://www.who.int/malaria/publications/world-malaria-report-2016/report/en/">About 70 percent</a> of malaria deaths were in children younger than five.</p>
<p>Malaria is not just a disease that happens “over there.” Without continued leadership from the United States, diseases like Zika and malaria will weaken public health throughout the Americas, including in the U.S. </p>
<p>The U.S. has been a leader in advancing global health, but recent policy recommendations will erode efforts to combat these threats. As a public health physician, former policymaker and president of a comprehensive research university, I am increasingly concerned about these shifts.</p>
<h2>Funding cuts jeopardize Americans and our neighbors</h2>
<p>The first potentially damaging shift is that <a href="https://www.washingtonpost.com/world/national-security/trump-administration-seeks-to-cut-funding-to-united-nations/2017/01/25/4539d032-e349-11e6-a453-19ec4b3d09ba_story.html">the U.S. administration has proposed drastic cuts</a> to the United Nations, its agencies and global health programs on the front lines of fighting disease. Walking away from these investments not only hurts communities abroad,<a href="http://www.cnn.com/2017/01/27/opinions/cuts-to-united-nations-hurt-united-states-yeo-opinion/"> it puts the health of Americans at risk.</a> We need a fully funded U.N. so it can carry out its vital work in coordinating the response to pandemics, stopping preventable diseases and addressing global health emergencies.</p>
<p>A second move could further harm health in coastal communities, both in the U.S. and globally. A recent executive order proposes to roll back domestic efforts to combat climate change, even as its environmental and health impacts grow. The people of Miami, Florida are sadly aware of the <a href="http://www.miamiherald.com/news/local/community/miami-dade/miami-beach/article129284119.html">risk of rising sea levels</a> on their homes and businesses. Less understood is the major impact that climate change has on many diseases.</p>
<p>A <a href="https://www.ipcc.ch/report/ar5/syr/">recent report</a> from the U.N. Intergovernmental Panel on Climate Change found that weather extremes contribute to the risk of mosquito-borne illnesses. Our warming planet is exposing more and more people to disease-carrying mosquitoes, which are migrating to higher elevations as temperatures rise.</p>
<p>University of Miami Professor Douglas O. Fuller, an expert in remote sensing, is <a href="http://climate.miami.edu/impact-on-health/dangerous-migration/">documenting the alarming distribution patterns of mosquitoes across the globe</a>. He observes, “As climate changes and tropical bioclimatic zones shift upslope to replace temperate zones, a lot more people will be exposed to disease.” (You can read more about this global impact in the University’s <a href="http://climate.miami.edu">Climate Change Special Report</a>.)</p>
<h2>Diseases continue to cross borders</h2>
<p>The Americas are increasingly vulnerable. Risk for intense weather events is increasing, and with it, the possibility of a broader natural habitat for disease-spreading mosquitoes. </p>
<p>From 2015-2016, a particularly strong El Niño put <a href="http://www2.paho.org/hq/index.php?option=com_docman&task=doc_view&Itemid=270&gid=38146&lang=en">Colombia in peril</a>: malaria cases reached 83,356 during this period – almost twice as many as in 2014. In November 2016 <a href="https://community.apan.org/pfa/hurricanemathew/b/12_oct/posts/map-of-malaria-cases">Hurricane Matthew</a> struck Haiti, and malaria cases reached 21,430 – almost 20 percent more than in 2015. </p>
<p>This year, <a href="http://www.bbc.com/mundo/noticias-america-latina-39259721">El Niño Costero</a> hit Peru, flooding towns and putting over 672,000 people at risk of dengue, chikungunya, Zika and malaria.</p>
<h2>Together we can end malaria for good</h2>
<p>There is, however, reason for hope. We know that when the international community mobilizes, we see results. In the last 15 years, targeted investments have strengthened health systems for malaria prevention, control and elimination. </p>
<p>New strategies are now being developed as part of a Centers for Disease Control and Prevention-funded collaboration with four Florida universities, including the Univerity of Florida, the University of South Florida, Florida International University and the University of Miami. Led by the University of Florida, <a href="http://news.ufl.edu/articles/2016/12/four-state-universities-collaborate-on-10-million-center-to-address-zika-and-other-diseases.php">the Southeast Regional Center of Excellence in Vector-Borne Disease: The Gateway Program </a>will help prevent the spread of Zika and other vector-borne diseases in the U.S. and, ultimately, the globe. </p>
<p>Here at UM, Professor John Beier will lead UM’s component of the five-year project that will build on research to develop new <a href="http://climate.miami.edu/impact-on-health/battling-vector-borne-diseases/">mosquito control strategies</a> in Africa and Latin America.</p>
<p>From 2000-2014, the Americas reduced malaria cases by 67 percent and deaths by 79 percent. We are close to eliminating malaria in the region, but according to the <a href="http://www2.paho.org/hq/index.php?option=com_topics&view=article&id=33&Itemid=40757">Pan American Health Organization</a>, more than 132 million people remain at risk of mosquito-borne illnesses.</p>
<p>Worldwide, mosquito-borne illnesses such as malaria pose serious threats, with an estimated <a href="http://www.who.int/malaria/publications/world-malaria-report-2016/report/en/">222 million people infected</a> in 2015. </p>
<p>Malaria not only kills but also prevents economic growth. In endemic countries, malaria can account for as much as <a href="http://www.rollbackmalaria.org/files/files/aim/RBM_AIM_Advocacy_pull-out_EN-lores.pdf">40 percent</a> of budgets for public health. This leaves poor countries at continued risk for other debilitating and deadly diseases. </p>
<p>On <a href="http://www.rollbackmalaria.org/calendar-of-events/world-malaria-day">World Malaria Day</a>, it is important to know malaria’s reach – and to understand that the fight against this disease must reach across the borders of nations, just as the mosquitoes do.</p><img src="https://counter.theconversation.com/content/76556/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Julio Frenk serves on the board of directors of the United Nations Foundation.
</span></em></p>Malaria has long menaced the world, but gains have occurred. Those efforts could now be stymied by budget cuts, however. Here’s how a disease that knows no borders could widen its deadly reach.Julio Frenk, President, University of MiamiLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/674472016-10-27T00:51:27Z2016-10-27T00:51:27ZPitting mozzies against mozzies to stop the spread of disease<figure><img src="https://images.theconversation.com/files/142973/original/image-20161024-28420-1o2tc0l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Cages full of hand reared yellow fever mosquitoes await research (or possibly release)</span> <span class="attribution"><span class="source">Cameron Webb, NSW Health Pathology/University of Sydney</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Mosquitoes and the burden of disease they cause continue to weigh down many communities around the world. Despite their fragile appearance, mosquitoes continue to resist our best efforts to eliminate them. We’ve drained and polluted their wetland homes, and we’ve filled the skies with clouds of insecticides, but still they persist.</p>
<p>There is no reason why mosquito-borne disease won’t continue to spread in the decades ahead. While <a href="https://theconversation.com/is-climate-change-to-blame-for-outbreaks-of-mosquito-borne-disease-39176">climate change, urbanisation and globalisation</a> will all influence future mosquito-borne disease risks, some of our current control products are also losing their potency.</p>
<p>In many ways, our efforts to control mosquitoes have also been our undoing. We constantly underestimate the resilience of mosquitoes. The more insecticides we use to try and kill mosquitoes, the greater the likelihood they will <a href="http://onlinelibrary.wiley.com/doi/10.1111/aen.12186/full">develop resistance to these chemicals</a>. We need to look at alternative ways to control mosquitoes, and a new project pitting mosquitoes against mosquitoes is being trialled in Australia.</p>
<h2>Bugging the mosquito</h2>
<p>While there are thousands of mosquito species worldwide (<a href="http://www.publish.csiro.au/book/6391/">over 300 in Australia alone</a>), the yellow fever mosquito (<em>Aedes aegypti</em>) is of greatest concern when it comes to outbreaks of dengue, chikungunya and Zika viruses. Second on the list is the Asian tiger mosquito (<em>Aedes albopictus</em>), a severe pest that also transmits these viruses. These <a href="https://theconversation.com/new-mosquito-threats-shift-risks-from-our-swamps-to-our-suburbs-56350">two exotic mosquitoes</a> have proven great at invading the world, spreading outwards to live with us in our cities. And they do love biting people.</p>
<p>It is important to remember that only female mosquitoes bite in pursuit of blood. Male mosquitoes do not, feeding only on nectar.</p>
<p>New approaches using an insect-specific bacteria have been developed that can sabotage mosquito populations. This works by either disrupting their reproduction or blocking their ability to transmit pathogens.</p>
<p>Scientists have concentrated their research on a naturally occurring insect bacteria, <a href="http://onlinelibrary.wiley.com/doi/10.1111/aen.12068/full"><em>Wolbachia</em></a>.</p>
<p><em>Wolbachia</em> doesn’t naturally infect all mosquitoes. However, studies have shown female mosquitoes infected in a laboratory with <em>Wolbachia</em> pass the infection through to their eggs. Then when males infected with the bacteria mate with uninfected females, the female’s eggs do not hatch. The reasons for this <a href="https://www.scientificamerican.com/article/fighting-mosquitoes-with-mosquitoes/">are not yet fully understood</a> but is known as “cytoplasmic incompatibility”.</p>
<p>Male <em>Wolbachia</em>-infected mosquitoes reared in the laboratory can be released into the field. As females only mate once, each successful mating results in no eggs hatching in the next generation. Therefore, the mosquito population shrinks over time. </p>
<p>Given these frisky male mosquitoes are better at finding female mosquitoes than we are with our insecticides, this approach could be a winner. It avoids increasing the risks of insecticide resistance and reduces the risks of other species in the area being <a href="https://entomologytoday.org/2015/03/23/wolbachia-bacteria-can-control-mosquitoes-with-fewer-chemicals/">impacted by insecticides</a>.</p>
<h2>How would this beat disease?</h2>
<p>Trials that use males carrying this bacteria to suppress mosquito populations of the Asian tiger mosquito are now occurring in the <a href="http://www.nature.com/news/us-reviews-plan-to-infect-mosquitoes-with-bacteria-to-stop-disease-1.19967">USA</a> and <a href="https://www.theguardian.com/world/2015/may/24/sterile-mosquitoes-released-in-china-to-fight-dengue-fever">China</a>. Singapore recently began its first trials <a href="http://www.nea.gov.sg/public-health/environmental-public-health-research/wolbachia-technology/project-wolbachia-singapore">releasing bacteria-infected male yellow fever mosquitoes</a> throughout their high-rise apartments in an effort to study and remove mosquito populations that have proven tricky to control.</p>
<p>The <a href="http://www.eliminatedengue.com/program">Eliminate Dengue</a> group from Monash University is also using this type of bacteria for population replacement of the yellow fever mosquito. In their novel approach, once the bacteria is established in the population of mosquitoes, dengue, Zika and chikungunya viruses cannot infect the mosquito, making the insect population resistant to transmission. Releases of these mosquitoes have been underway in northern Australia for more than five years, and the <a href="http://www.abc.net.au/news/2016-10-27/zika-eliminate-dengue-project-to-expand-after-qld-success/7969038">results are very promising</a>. There are plans to expand the approach to <a href="https://www.theguardian.com/world/2016/oct/26/mosquitos-infected-wolbachia-bacteria-zika-virus">South America</a>. </p>
<h2>Where to from here?</h2>
<p>These new ways forward seem to offer a choice between using this common bacteria for either population suppression or replacement. The great benefit is that all these approaches use mosquitoes against mosquitoes.</p>
<p>While early successes of laboratory and field trials are already coming in, these small-scale and well-funded research projects may not reflect the reality of what is required in the long-term. How can we “scale up” these approaches to deploy them across the many major urban centres suffering from outbreaks of dengue and other mosquito-borne diseases?</p>
<p>This is where the <a href="https://blog.verily.com/2016/10/introducing-debug-project.html">Debug Project</a> comes in. A newly announced partnership between Verily (formerly <a href="http://bits.blogs.nytimes.com/2015/12/07/alphabets-life-sciences-business-has-a-new-name-verily/">Google Life Sciences</a>) and CSIRO, together with the University of Queensland and James Cook University, sets out to investigate how effective the release of <em>Wolbachia</em>-infected male mosquitoes is for mosquito control. Most importantly, the project will also be developing new technologies for the cost-effective mass rearing of mosquitoes. This is a critical step in being able to apply this approach to major cities impacted by mosquito-borne disease.</p>
<p>The early stages of the project will involve scientists releasing laboratory reared male mosquitoes and following them to see where and how far they fly, and how successfully they can track down and mate with local female mosquitoes. As well as demonstrating that this approach can actually reduce the overall mosquito population, the research will fill many of the gaps in our understanding of male mosquito biology. </p>
<p>The one thing we know is critical to upscaling any of these approaches is strong engagement with the local community. Without community support and participation, these projects are primed for failure. So, how would you feel about scientists releasing millions of “bacteria-infected male mosquitoes” in your neighbourhood? As the swathes of new non-biting males buzz around you and your house searching for females, please – don’t get out the bug spray.</p><img src="https://counter.theconversation.com/content/67447/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cameron Webb and the Department of Medical Entomology, NSW Health Pathology, have been engaged by a wide range of insect repellent and insecticide manufacturers to provide testing of products and provide expert advice on mosquito biology. Cameron has also received funding from local, state and federal agencies to undertake research into mosquito-borne disease surveillance and management</span></em></p><p class="fine-print"><em><span>Nigel Beebe works for University and the CSIRO and receives funding from state governments, (WA Health), national (NHMRC), and international (National Institutes of Health, USA and Verily) funding bodies to carry our research on mosquito biology and control.
</span></em></p>Upscaling the success of emerging mosquito control technologies relies on automating the rearing and release of millions of mosquitoes. Australia is to become the testing ground for a novel strategy.Cameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of SydneyNigel Beebe, Associate professor, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/643562016-09-01T05:58:00Z2016-09-01T05:58:00ZAre mosquitoes to blame for the spread of ‘flesh-eating’ bacteria?<figure><img src="https://images.theconversation.com/files/136161/original/image-20160831-30790-1e566fh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A common mosquito in coastal regions of Australia, Aedes vigilax. Could it be spreading the pathogen that causes Buruli ulcer?</span> <span class="attribution"><span class="source">Mr Stephen Doggett (NSW Health Pathology)</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Those who live and holiday on the coast are no strangers to mosquitoes. Our coastal wetlands are home to abundant mosquito populations. During summer, swarms of these nuisance, biting pests can make life quite unpleasant. They also pose a health risk.</p>
<p>Thousands of Australians fall ill following mosquito bites each year but it’s the suspected link between mosquito bites and an increasing incidence of mysterious “Buruli ulcers” that has <a href="https://www2.health.vic.gov.au/about/news-and-events/healthalerts/bairnsdale-buruli-ulcer">Victorian authorities on alert</a>.</p>
<h2>What is a Buruli ulcer?</h2>
<p>The Buruli ulcer, also known locally as the “Bairnsdale ulcer”, is caused by an environmental pathogen, <em>Mycobacterium ulcerans</em>. The bacterium is typically associated with many wetland areas but there is uncertainty about how individuals become infected. Is it contact with water, soil or plants? Perhaps it is insect bites?</p>
<p>Initially, infection with the bacterium does not cause serious problems but, over a period of <a href="http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0002463">many months</a>, can lead to a destructive skin ulcer. A toxin, mycolactone, produced by the bacterium causes much of the problem by inhibiting the body’s immune response.</p>
<p>With an early diagnosis, <a href="https://www.mja.com.au/journal/2014/200/5/treatment-and-prevention-mycobacterium-ulcerans-infection-buruli-ulcer-australia">treatment</a> is straight forward and serious tissue damage can be avoided. </p>
<p>In more serious cases, amputation is required. Antibiotics and surgery are typical treatments but scientists are now investigating the possibility that <a href="https://pozible.com/project/22449">maggot therapy</a> (where maggots eat away the dead tissue in order for new tissue to grow) could be a useful treatment too.</p>
<h2>Where in the world are Buruli ulcers found?</h2>
<p>Internationally, the <a href="http://www.who.int/buruli/en/">Buruli ulcer</a> is considered an important but neglected disease of tropical and sub-tropical regions, <a href="http://www.who.int/gho/neglected_diseases/buruli_ulcer/en/">particularly Africa</a>. While it has been detected in more than 30 countries and around 6,000 cases are reported each year, in many regions, the full extent of the problem is unknown.</p>
<p>The Buruli ulcer has been reported in Australia for decades. Since the first case was described in 1948, cases have occurred in <a href="https://www.mja.com.au/journal/2006/185/3/mycobacterium-ulcerans-infection-rediscovered-focus-capricorn-coast-region">Queensland</a>, <a href="https://www.mja.com.au/journal/2014/200/5/treatment-and-prevention-mycobacterium-ulcerans-infection-buruli-ulcer-australia?0=ip_login_no_cache%3D3d859d9d0d9a0810ee466da187156fd4">the Northern Territory</a>, <a href="http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0002463">Western Australia</a> and <a href="http://europepmc.org/abstract/med/17223764">New South Wales</a>. In recent years, numerous cases have been reported from coastal Victoria, particularly the Mornington Peninsula and Bellarine Peninsula, which has sparked concern. Buruli ulcers seems to be on the rise, with around 150 cases reported in Victoria over the past 18 months.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/136181/original/image-20160901-30772-1ku5hrw.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/136181/original/image-20160901-30772-1ku5hrw.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/136181/original/image-20160901-30772-1ku5hrw.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/136181/original/image-20160901-30772-1ku5hrw.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/136181/original/image-20160901-30772-1ku5hrw.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/136181/original/image-20160901-30772-1ku5hrw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=473&fit=crop&dpr=1 754w, https://images.theconversation.com/files/136181/original/image-20160901-30772-1ku5hrw.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=473&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/136181/original/image-20160901-30772-1ku5hrw.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=473&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Buruli ulcers can be treated with antibiotics, but left untreated can be much more severe.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Mycobacterium_ulcerans#/media/File:Buruli_ulcer_traveler.png">Wikimedia Commons</a></span>
</figcaption>
</figure>
<h2>Are mosquitoes responsible for the spread?</h2>
<p>Insects and other arthropods can spread pathogens in different ways. “Biological transmission” occurs when the insect itself is infected and passes on the pathogen when it bites. This is the case for <a href="http://theconversation.com/does-zika-virus-pose-a-threat-to-australia-53557">Zika virus</a>, which is transmitted in the saliva of an infected mosquito. </p>
<p>Diseases can also spread through “mechanical transmission”, in which a pathogen is carried on the body of the insect between infected hosts or other substances. This is how <a href="http://theconversation.com/should-i-throw-away-food-once-a-fly-has-landed-on-it-50895">flies move bacteria</a> between waste and our food preparation areas.</p>
<p>Given reports that ulcers appeared at what was first thought to be an insect bite, could mosquitoes be to blame? </p>
<p>There is no conclusive evidence mosquitoes are involved in the spread of the bacterium that causes the Buruli ulcer but there is growing evidence their role may be one of multiple pathways of infection.</p>
<p>A <a href="http://wwwnc.cdc.gov/eid/article/13/11/06-1369_article">small 2007 study</a> in Point Lonsdale, Victoria, detected <em>Mycobacterium ulcerans</em> among approximately 11,000 locally collected mosquitoes. </p>
<p>A <a href="http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0001305#s2">larger study</a> in the Bellarine Peninsula tested almost 42,000 mosquitoes collected between December 2004 and December 2009. It found that at some locations, up to four in every 1,000 mosquitoes tested positive for the presence of <em>Mycobacterium ulcerans</em>.</p>
<p>Are the mosquitoes spreading the pathogen? If they are, how is it being transmitted? Is the pathogen in the local environment and people simply pick up the infection through contact with soil or water containing the pathogen? Is it just a coincidence mosquitoes are infected?</p>
<p>A <a href="http://aem.asm.org/content/76/18/6215.short">recent study</a> demonstrated that when consumed by immature mosquitoes in local waterways, <em>Mycobacterium ulcerans</em> does not continue when the adult mosquitoes emerge. It appears unlikely the mosquitoes are injecting bacteria-infected spit when they bite but what about bacteria found on their bodies, particularly those that stick into us as they suck up our blood?</p>
<p>More laboratory studies are needed to confirm how mosquitoes may be transmitting the bacteria to people from the local environment or wildlife.</p>
<h2>What about local wildlife?</h2>
<p>There is <a href="http://link.springer.com/article/10.1007/s40588-015-0013-3">complexity underlying the transmission</a> of <em>Mycobacterium ulcerans</em>. Generally thought to be an environmental pathogen of slow-moving waterways, there is some evidence <a href="http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0000791">native wildlife</a> may also be involved, <a href="http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0002668">particularly possums</a>. </p>
<p>Perhaps the pathogen is being circulated between possums, mosquitoes and the local environment and somewhere along this cycle, humans are exposed.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/136182/original/image-20160901-30772-1inal1o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/136182/original/image-20160901-30772-1inal1o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/136182/original/image-20160901-30772-1inal1o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/136182/original/image-20160901-30772-1inal1o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/136182/original/image-20160901-30772-1inal1o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/136182/original/image-20160901-30772-1inal1o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/136182/original/image-20160901-30772-1inal1o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/136182/original/image-20160901-30772-1inal1o.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">Possums have also been implicated in the spread of Buruli ulcers.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/cskk/2268890574/">cskk/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>How can we protect ourselves?</h2>
<p>It will be tricky for authorities to provide effective advice on avoiding infection until the exact processes of transmission are understood.</p>
<p>If mosquitoes are playing a role, avoiding mosquito bites will be critical. Minimising time in areas where mosquitoes are most active (dawn and dusk close to coastal wetlands), covering up where possible, and <a href="http://theconversation.com/chemical-or-natural-whats-the-best-way-to-repel-mozzies-36879">wearing topical insect repellents</a> will help reduce the risks of the Buruli ulcer – and more common mosquito-borne diseases such as <a href="http://theconversation.com/explainer-what-is-ross-river-virus-24630">Ross River virus</a>.</p>
<p>Take care to minimise contact with water or soil around these regions too, particularly if you have cuts or abrasions.</p>
<p>The Buruli ulcer is a mysterious condition with numerous questions about its spread yet to be answered. We need to <a href="http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0000911">meet many challenges</a> before we fully understand this unusual pathogen and its relationship with the local environment and wildlife.</p><img src="https://counter.theconversation.com/content/64356/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cameron Webb and the Department of Medical Entomology, NSW Health Pathology and University of Sydney, have been engaged by a wide range of insect repellent and insecticide manufacturers to provide testing of products and provide expert advice on biting insect biology. Cameron has also received funding from local, state and federal agencies to undertake research into mosquito-borne disease surveillance and management.</span></em></p>A rise in cases of the mysterious “Bairnsdale ulcer” in coastal Victoria has health authorities on alert and scientists investigating the role of mosquitoes in the spread.Cameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/624062016-08-25T09:51:47Z2016-08-25T09:51:47ZUnderstanding mosquitoes can help us find better ways to kill them<p>Astronomer Royal Dr. Martin Rees <a href="http://web.calstatela.edu/faculty/kaniol/a360/Once-Future-Universe/Q302082C.pdf">wrote in 1999</a>: “What makes things baffling is their degree of complexity, not their sheer size… a star is simpler than an insect.” </p>
<p>You might not think an insect like a mosquito could be so complex, so I thought I would share some lesser-known facts about them. </p>
<p>I am a mosquito researcher who lives and works in Florida, and when I tell people what I do for a living, I get all sorts of questions. Not surprisingly, most of the questions I get from the general public have to do with blood feeding and mosquitoes’ disease-transmitting abilities. And like many researchers in my field, I’ve spent a lot of time studying mosquitoes to find better ways to control or eradicate them.</p>
<p>Headlines about <a href="http://www.nytimes.com/2016/08/24/health/florida-investigates-new-zika-cases-on-gulf-coast-and-in-miami.html">Zika</a>, <a href="https://www.bostonglobe.com/metro/2016/08/20/mosquitoes-test-positive-for-west-nile-virus-watertown/SQmTceajXMrz307ZZqGleO/story.html">West Nile</a> or any other mosquito-borne virus might have you looking at the mosquitoes buzzing around your backyard with some suspicion.</p>
<p>But did you know that many mosquito species can’t actually spread pathogens or parasites? And while no one likes getting bitten by mosquitoes, you might be surprised (and even a little fascinated) at the complex adaptions mosquitoes have developed to locate their favorite food sources. </p>
<h2>Blood meals are only for the ladies</h2>
<p>The females of most species of mosquito are blood feeders (a practice entomologists call hematophagy), because they use proteins in blood to make yolk for their eggs. They also consume plant nectar to fuel their activities to locate blood sources and lay eggs. Male mosquitoes, on the other hand, feed only on plant nectar.</p>
<p>And in a few species females can produce eggs without a blood meal, using nutrients carried over from their juvenile stage to make yolk and produce eggs. This is termed autogeny.</p>
<p>That mosquito you swat away when you are enjoying time outside has gone through a whole lot to find you.</p>
<p>Some blood-feeding insects, like lice and fleas, live on or near their hosts. But mosquitoes travel to locate hosts. While some have to travel long distances, other species are adapted to live in close quarters with their preferred blood source. </p>
<p>In fact, that is an important reason the <em><a href="https://theconversation.com/zika-aedes-aegypti-mosquitoes-love-biting-humans-and-thats-why-they-spread-viruses-so-well-54238">Aedes aegypti</a></em> mosquito is so effective at transmitting dengue and Zika viruses to humans. It thrives in environments close to humans. While some mosquito species feed at night, when their preferred hosts are not active and temperatures are cooler, others, like <em>Ae. aegypti</em>, are able to feed during the warmer daytime when humans are out and about.</p>
<p>Mosquitoes locate their hosts using receptors on their antennae and mouthparts that pick up on cues that hosts emit, such as CO2 and water vapor in our breath, and chemicals in our sweat such as lactic acid, butyric acid and fatty acids. </p>
<h2>Finding a nice spot for dinner</h2>
<p>Once a mosquito has landed on a host, it has to find the best location to take a blood meal. Mosquitoes that prefer to feed on humans, such as <em>Ae. aegypti,</em> tend to seek a blood meal on our feet, ankles and legs. These areas of our bodies are accessible and can be more “aromatic.” Blood feeding may also go undetected at those locations.</p>
<p>Chemoreceptors (“taste buds”) located on their mouthparts and antennae help the mosquito taste the skin for certain “flavors” and let them know if a patch of skin is a good spot for a blood meal. In addition, mosquitoes have “touch” receptors on their mouthparts to signal whether they are well-positioned to penetrate skin with their stylets, which pierce the skin and suck blood. </p>
<p>Even then, mosquitoes may find they have to probe multiple times to search for a blood vessel. If the search is successful, feeding begins. If not, the mosquito will withdraw its stylets and attempt to feed at another site. </p>
<p>The host’s body will try to stop the bleeding by constricting blood vessels and coagulating the blood to form a clot. These are all hemostatic (stopping blood loss) properties. </p>
<p>In response, the saliva from blood-feeding mosquitoes has evolved to contain various anti-hemostatic components to keep blood flowing, like anticoagulants to keep clots from forming and vasodilators to stop vessels from constricting. The saliva also has painkilling components. This means that host animals are sometimes unaware they are being fed upon. </p>
<h2>Mosquitoes don’t want to get infected with our germs</h2>
<p>While enjoying a blood meal, female mosquitoes may pick up a pathogen or parasite from their host and then transmit it to other hosts during subsequent feedings. That means the mosquito is infected by that bacteria or pathogen, even if it doesn’t make the mosquito sick.</p>
<p>However, like us, mosquitoes have defenses against infection. </p>
<p>First, the lining of mosquito midgut (equivalent of stomach and small intestine) has properties that can prevent the pathogen or parasite from getting out of the gut. </p>
<p>If the pathogen or parasite makes it through the gut barrier, it has to make its way through the mosquito’s blood-like fluid, called hemolymph, which contains circulating immune cells, called hemocytes, which are similar to our white blood cells. </p>
<p>If the pathogen or parasite gets by these immune cells, it may successfully invade the mosquito salivary glands. At that point, it is far more likely to be transmitted to another host during the mosquito’s next blood feeding.</p>
<p>So, any pathogen and parasite that can be transmitted by a mosquito has to make it through a lot of barriers. Even though there are about <a href="https://www.cdc.gov/malaria/about/biology/mosquitoes/">3,500</a> of mosquitoes worldwide, many aren’t capable of transmitting disease-causing pathogens or parasites to animals. And not all of the species that can carry pathogens actually bite humans.</p>
<p>So, what makes some mosquitoes vectors? The pathogens and parasites that certain mosquito species can transmit to humans, like Zika virus or <a href="http://dx.doi.org/10.3390/v6114479">dengue</a> or the parasite that <a href="http://dx.doi.org/10.1590/0074-0276130553">causes malaria</a>, for instance, have evolved to tolerate or evade the numerous immune barriers in those mosquitoes. A mosquito that carries a pathogen is considered a vector if it is able to pass it on to the source of their next blood meal.</p>
<h2>Why we study mosquitoes</h2>
<p>Researchers like me study mosquito biology because they are fascinating creatures. But we also study mosquito biology because understanding how mosquitoes eat, mate and defend themselves against infection can help us develop strategies to control or eradicate them. </p>
<p>For instance, researchers may figure out the vulnerability of a particular pest and come up with tools to exploit that. Researchers who study the <a href="https://theconversation.com/controlling-mosquito-sex-lives-is-one-way-to-fight-malaria-19668">mating and reproductive biology</a> of a pest may put that knowledge into use for a <a href="https://theconversation.com/to-fight-zika-lets-genetically-modify-mosquitoes-the-old-fashioned-way-57789">sterile insect program</a> to eradicate it. </p>
<p>Think about feeding patterns. Does the mosquito primarily feed on a nonhuman host but may opportunistically feed on humans? Does the mosquito feed primarily at dusk, during the night or during the day? Such data help inform the specific steps of vector control measures so that measures are efficient and effective. </p>
<p>The more we know about these fascinating creatures, the better we can defend ourselves against the one that can spread infection.</p><img src="https://counter.theconversation.com/content/62406/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Aparna Telang has previously received funding from NIAID/NIH. </span></em></p>While no one likes getting bitten by mosquitoes, you might be surprised (and even a little fascinated) at the complex adaptions mosquitoes have developed to locate their favorite food sources.Aparna Telang, Assistant Professor of Biology, University of South FloridaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/566922016-06-20T20:13:16Z2016-06-20T20:13:16ZHow we convinced people to trust a new innovative approach to eliminate dengue<figure><img src="https://images.theconversation.com/files/126887/original/image-20160616-19916-yyxgu4.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Community members visit our insectary and diagnostic laboratory to gain a better understanding about Aedes mosquitoes and Wolbachia. </span> <span class="attribution"><span class="license">Author provided</span></span></figcaption></figure><p>In recent years, scientists have found an alternative to significantly <a href="http://www.who.int/mediacentre/factsheets/fs117/en/">decrease dengue transmission by the mosquito <em>Aedes aegypti</em></a>. By transferring Wolbachia, a bacteria that stops the dengue virus from surviving in their mosquito hosts, into <em>Aedes aegypti</em> mosquitoes and then releasing them to the general population, scientists dream of <a href="http://www.nature.com/nature/journal/v476/n7361/full/nature10355.html">eliminating dengue</a> worldwide. </p>
<p>But releasing mosquitoes to communities requires a high amount of trust. How do we convince people that spreading mosquitoes can eliminate dengue when they have long came to understand that <em>Aedes</em> mosquitoes transmit dengue? </p>
<p>The answer? Careful preparation and community engagement.</p>
<p>I lead the Eliminate Dengue Project in Yogyakarta (EDP-Yogya), the first project to use Wolbachia to reduce dengue cases in Indonesia, the most dengue-vulnerable country in Asia. Funded by Tahija Foundation, EDP-Yogya works in collaboration with EDP-Global led by Professor Scott O'Neill, based at Monash University. </p>
<p>Two districts in Sleman, Yogyakarta became our release sites. For two years since 2011, while we prepared for the first small-scale release of Wolbachia infected mosquitoes, we carried out intensive community engagement. </p>
<h2>Community engagement</h2>
<p>We worked closely with the smallest community unit, called Rukun Tetangga (RT) to gain trust. An RT consists of about 20 to 30 households. We held face-to-face community meetings to educate the community on dengue-related subjects, both piggybacking on their existing meetings and arranging special meetings. </p>
<p>We formed community referral groups to be able to discuss key issues raised by the community as well as issues to be put to the community. As the project develops, members of this group are often called on as resource persons for other communities. </p>
<p>We also adopted the saying “seeing is believing”. Community members visit our insectary and diagnostic laboratory to gain a better understanding about Aedes mosquitoes and Wolbachia. These visits to our lab create a strong sense of transparency. We hide nothing from our community. </p>
<p>Two years into the preparatory phase, we built a stakeholder inquiry system (SIS) to capture any community concerns, opinions and complaints as the project moves closer to the mosquito release. We use various mediums from direct face-to-face conversation, short text messages, telephone and email. We monitor concerns daily and we develop protocols to address these concerns. </p>
<p>Finally, building trust also involves sharing information back to the community. Every two months, progress and activities in specific hamlets are communicated via newsletters (“Pawartos”), distributed to all households in the community. </p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/126889/original/image-20160616-19913-1y0q0gk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/126889/original/image-20160616-19913-1y0q0gk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/126889/original/image-20160616-19913-1y0q0gk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/126889/original/image-20160616-19913-1y0q0gk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/126889/original/image-20160616-19913-1y0q0gk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/126889/original/image-20160616-19913-1y0q0gk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/126889/original/image-20160616-19913-1y0q0gk.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">EDP staff distributing newsletters to the community.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Community consent</h2>
<p>Enhancing community understanding in a community-based project like EDP-Yogya is a prerequisite toward acceptance of the project. However, improved community understanding about dengue and Wolbachia intervention does not imply approval from the community. </p>
<p>Consent must be obtained from the research participants. We collaborate with EDP Global at Monash University, and for the first release in Sleman district, the Independent Review Board requests individual consent from each household member. We obtained approval from nearly 4,500 people.</p>
<p>From the Sleman trial, we learnt obtaining individual consent can generate conflicts in the community. Culturally, communities in these areas use collective decision-making process when dealing with community issues. The protocol protects the rights of people who refuse the release over those who approve. </p>
<p>Additionally, obtaining individual consent required tedious work. Although we managed to obtain more than 95% approval, this approach is impractical to do on a larger scale. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/126890/original/image-20160616-19925-1vkh2ye.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/126890/original/image-20160616-19925-1vkh2ye.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/126890/original/image-20160616-19925-1vkh2ye.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/126890/original/image-20160616-19925-1vkh2ye.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/126890/original/image-20160616-19925-1vkh2ye.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/126890/original/image-20160616-19925-1vkh2ye.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/126890/original/image-20160616-19925-1vkh2ye.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">Community leaders signing informed consent.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Finally, a low percentage of household members who rejected the intervention turned out to have influenced the release areas. When one household rejects the mosquito release, we do not release the mosquitoes in that household and its surrounding areas within the radius of 25-50 square meters. As a result, 5% of the population that doesn’t approve does not translate to 5% of the area not released, but somewhat larger. </p>
<p>Based on the experience in Sleman, for Bantul release we obtained community consent but still allowed individuals to reject. All RTs in Jomblangan and Singosaren (Bantul district) gave consent and no households refused the release. </p>
<p>We also changed the method to releasing young <em>Aedes</em> eggs instead of adult mosquitoes. We engaged the community to hatch Wolbachia-infected eggs, placed in buckets, in their households. Involving the community to hatch _Aedes _eggs in their own houses creates a higher sense of ownership. </p>
<h2>Result</h2>
<p>Weekly monitoring of the local <em>Aedes</em> mosquito found the bacteria spread through more than 80% of the local population. The mosquitoes have remained infected, showing that the establishment of Wolbachia in the population is sustainable. </p>
<p>Our observation on dengue cases in the community revealed that once most mosquitoes are infected by Wolbachia, there was no evidence of local dengue transmission. This means that those who have had dengue could have been infected from outside the release areas. </p>
<p>Without community involvement and consent, it would have been impossible to achieve this positive result. Our next step is to carry the successes in Sleman and Bantul to a larger population: the city of Yogyakarta with around 450,000 residents. By 2020, we hope Indonesia will adopt the use of Wolbachia in dengue-prevention nationwide.</p><img src="https://counter.theconversation.com/content/56692/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Adi Utarini works for the Eliminate Dengue Project in Yogyakarta in Faculty of Medicine Universitas Gadjah Mada, Yogyakarta, Indonesia. She receives funding from Tahija Foundation for this project. </span></em></p>How do we convince people that spreading Wolbachia-infected mosquitoes can eliminate dengue when they have long came to understand that mosquitoes transmit dengue?Adi Utarini, Professor in Public Health and Project Leader of Eliminate Dengue Project Yogyakarta, Faculty of Medicine, Universitas Gadjah Mada Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/578442016-04-28T10:53:27Z2016-04-28T10:53:27ZLyme disease: a ticking time bomb<figure><img src="https://images.theconversation.com/files/119664/original/image-20160421-27001-1itukb9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Ixodus ricinus tick, which spreads Lyme disease in Europe.</span> <span class="attribution"><span class="source">Richard Bartz </span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>On any ranked list of nasty diseases transmitted by mosquitoes, ticks and fleas in the Western world, <a href="http://www.cdc.gov/lyme/"><em>Borrelia burgdorferi</em></a>, would have to lie near the top. These bacteria cause Lyme disease, which was <a href="http://www.ncbi.nlm.nih.gov/pubmed/836338">first recognised</a> in the US in the early 1970s among patients in Lyme, Connecticut. However, the oldest known case was the <a href="http://www.ncbi.nlm.nih.gov/pubmed/22426219">Tyrolean Iceman</a>, a 5,300-year-old Copper-age mummified individual, discovered in the Italian Alps.</p>
<p>Lyme disease is one of the fastest growing vector-borne diseases in the Western world – the threat it poses has become increasingly apparent in recent years. Estimates suggest that more than <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3879353/">300,000 people</a> are diagnosed with the disease each year in the US and more than <a href="http://www.ncbi.nlm.nih.gov/pubmed/19367096">65,000 cases</a> a year are diagnosed in Europe. However, the true number of people affected is probably underestimated due to under-reporting and the <a href="http://www.lymediseaseaction.org.uk/about-lyme/tests/">limitations of current diagnostic tests</a>.</p>
<p><em>Borrelia burgdorferi</em> is a spirochete (corkscrew-shaped bacterium) that consists of more than 20 sub-species, five of which can cause disease in humans. <em>Borrelia</em> can flourish inside the tick, where they migrate from the gut to the saliva glands. In this way, they can penetrate human skin when a tick takes a blood meal and disseminate via the blood to multiple tissues. To survive and establish infection, <em>Borrelia</em> <a href="http://www.ncbi.nlm.nih.gov/pubmed/26747708">mutates</a> in a number of ways to become invisible to the host’s immune system.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/119838/original/image-20160422-17378-1wt2yy6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/119838/original/image-20160422-17378-1wt2yy6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=395&fit=crop&dpr=1 600w, https://images.theconversation.com/files/119838/original/image-20160422-17378-1wt2yy6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=395&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/119838/original/image-20160422-17378-1wt2yy6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=395&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/119838/original/image-20160422-17378-1wt2yy6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=497&fit=crop&dpr=1 754w, https://images.theconversation.com/files/119838/original/image-20160422-17378-1wt2yy6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=497&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/119838/original/image-20160422-17378-1wt2yy6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=497&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"><em>Borrelia burgdorferi</em>.</span>
<span class="attribution"><span class="source">Centers for Disease Control and Prevention's Public Health Image Library</span></span>
</figcaption>
</figure>
<p>The main vector for transmitting the bacteria in Europe is the deer tick, <em>Ixodes ricinus</em>, but other <em>Ixodes</em> species act as vectors in the US and in Asia. Humans can become infected after being bitten by an infected tick. However, as <em>Ixodes</em> ticks can also transmit other pathogenic bacteria and viruses, it can be hard to diagnose Lyme disease among the potentially large number of infections that may have been contracted as a result of the tick bite, meaning it often goes untreated. </p>
<p>But it’s not just ticks we have to worry about. Lice, fleas, and mosquitoes have also been found to contain <em>Borrelia</em>. Worrying, <em>Borrelia</em> bacteria may also be transmitted <a href="http://www.medicaldaily.com/lyme-disease-contagious-clues-hint-it-may-be-sexually-transmitted-disease-267964">from person to person</a> through saliva, organ transplants, <a href="http://www.ncbi.nlm.nih.gov/pubmed/8014507">blood transfusions</a>, <a href="https://www.lymedisease.org/lyme-sexual-transmission-2/">sexual contact</a> or breast milk. It has <a href="http://www.scientificamerican.com/article/mothers-may-pass-lyme-disease-to-children-in-the-womb/">also been suggested</a> that Lyme disease could be transferred to a foetus via the placenta, however this has yet to be proven.</p>
<h2>What <em>Borrelia</em> can do to people</h2>
<p>Some individuals develop a bull’s eye-like rash, called <a href="http://www.lymediseaseaction.org.uk/about-lyme/rashes/">Erythma migrans</a> at the site of the tick bite, three to 30 days after infection. As infection spreads, <em>Borrelia</em> can also affect other skin sites, the nervous system, the joints or the heart. Brain infection is a rare but potentially serious complication, arising in 15% of untreated Lyme patients who go on to be very ill. This can also cause permanent neurological injury.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/119665/original/image-20160421-27017-12gai7o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/119665/original/image-20160421-27017-12gai7o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/119665/original/image-20160421-27017-12gai7o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/119665/original/image-20160421-27017-12gai7o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/119665/original/image-20160421-27017-12gai7o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/119665/original/image-20160421-27017-12gai7o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/119665/original/image-20160421-27017-12gai7o.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">
<figcaption>
<span class="caption">Hitting the target.</span>
<span class="attribution"><span class="source">Hannah Garrison/wikimedia</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Because of this wide range of non-specific symptoms, patients often don’t get a clear diagnosis or treatment options. When Lyme disease is suspected, laboratory tests to detect specific antibodies against <em>Borrelia burgdorferi</em> can help confirm the diagnosis – although these are <a href="http://www.lymediseaseaction.org.uk/about-lyme/tests/">far from perfect</a>. Some patients, about 10-20%, can develop a debilitating chronic condition called <a href="http://www.cdc.gov/lyme/postlds/">post-treatment lyme disease syndrome</a>, with symptoms that include arthritis, fatigue, muscle pain and minor cognitive impairments such as headaches and sleep disturbances.</p>
<p>Unfortunately, there is currently no vaccine available against Lyme disease. However, there are measures that can mitigate the risk of infection, including avoiding tick-infested areas, wearing personal protective measures to reduce the risk of tick bites and the use of <a href="http://www.ncbi.nlm.nih.gov/pubmed/11450675">antimicrobial treatments</a> following a tick bite. </p>
<p>Timely treatment for Lyme disease is crucial to prevent illness and avoid long-lasting symptoms. Early stages of Lyme disease can be effectively treated with antibiotics, but patients with the chronic variant may require months or even years of treatment before it resolves. Unfortunately, some physicians still view antibiotics as the only solution to this disease but chronically infected patients require multidisciplinary care – addressing all simultaneous infections, providing immune support and management of any other health complications.</p>
<h2>Tackling the threat</h2>
<p>The effects of the disease on so many body systems, and the debilitating impact on the life of the affected patient, have triggered a crisis that has far-reaching implications for public health and policy. When people get diagnosed with Lyme, they make a shift to a life of increasing uncertainty, particularly from a lack of adequate and credible information.</p>
<p>It’s clear, given the rise in clinical cases across the world and the number of people who continue to suffer even after antimicrobial treatment, that Lyme disease is spreading rapidly. For example, in the US the number of annual reported Lyme cases <a href="http://www.ilads.org/lyme/lyme-quickfacts.php">has increased about 25-fold</a> since the national surveillance began in 1982. </p>
<p>Many aspects of the disease mechanisms, such as the chronic condition, remain controversial or evolving, due to the scarcity of robust evidence-based data. There is not even one consistent terminology that defines “chronic Lyme disease”. More measures are also needed to resolve the crippling uncertainty surrounding the infection. We need more research to help develop reliable diagnostic tests, identify sub-populations of patients who are most likely to benefit from antibiotic treatment, and ultimately to ensure that Lyme disease does not become a pandemic reality.</p><img src="https://counter.theconversation.com/content/57844/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Hany Elsheikha is affiliated with The European Scientific Counsel for Companion Animal Parasites (ESCCAP) of UK & Ireland. </span></em></p>How a microbe from the ice age could wreck your life – and how to protect yourself.Hany Elsheikha, Associate Professor of Parasitology, University of NottinghamLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/498382015-11-09T03:55:14Z2015-11-09T03:55:14ZThere’s a fly in the ointment of solar-powered LED lighting<figure><img src="https://images.theconversation.com/files/101029/original/image-20151106-16273-2wpa0k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Disase carrying insects are attracted to light bulbs – a constraint of domestic solar energy.</span> <span class="attribution"><span class="source">Jon Nazca/Reuters</span></span></figcaption></figure><p>Household air pollution is estimated to <a href="http://www.who.int/phe/health_topics/outdoorair/databases/HAP_BoD_results_March2014.pdf?ua=1">kill more than 500,000 people</a> in Africa each year. Through solar energy, people can stop using dirty and extremely polluting fuels like kerosene in their homes. But with domestic solar energy comes an unintended consequence. When the light bulbs are switched on, they can attract disease carrying bugs.</p>
<p>Given the health threats of kerosene and other indoor pollutants, a number of initiatives are driving the use of solar power for domestic uses. Organisations associated with the UN <a href="http://se4all.org/">Sustainable Energy For All</a> initiative are promoting various programmes. </p>
<p>And donors are also moving into this space. One example is the <a href="https://www.gov.uk/government/news/solar-boost-to-release-africas-untapped-energy-potential">EnergyAfrica</a> campaign being driven by UK’s Department for International Development, or DFID. Its focus is on domestic solar, providing individual householders with systems to power small electrical devices in the home. This mainly involves light bulbs.</p>
<p>The irradiation potential for sunshine to provide this form of clean energy in Africa is <a href="http://solargis.info/doc/_pics/freemaps/1000px/ghi/SolarGIS-Solar-map-Africa-and-Middle-East-en.png">substantial</a>. There will undoubtedly be enormous health benefits provided that people switch from kerosene and other so-called dirty fuels, instead of adding solar to the mix of energy types they use.</p>
<h2>So what’s the problem?</h2>
<p>Let’s temporarily set aside the potential problems of <a href="http://www.cgdev.org/blog/dfid-energy-africa-campaign-launch-three-facts-one-bad-idea-one-way-forward">financing</a> and sustainability for individual householders unused to looking after complete solar systems. There is one glaring issue with providing electrical light into otherwise non-improved residences like mud huts with corrugated iron roofs: flying insects.</p>
<p>Many different types of insects are attracted to light sources. This is either in search of a mate or after taking a meal. Many insects attracted to lights may be harmless, but key species are known vectors of disease that affect both humans and animals. These include:</p>
<ul>
<li><p>domestic flies, which carry the bacteria that cause blinding <a href="http://www.who.int/topics/trachoma/en/">trachoma</a>;</p></li>
<li><p>mosquitoes, which carry the parasites that cause <a href="http://www.who.int/topics/malaria/en/">malaria</a>, <a href="http://www.who.int/topics/filariasis/en/">filariasis</a>, <a href="http://www.who.int/topics/dengue/en/">dengue</a>; and</p></li>
<li><p><a href="http://www.parasitesandvectors.com/content/6/1/341">sandflies</a>, which carry the parasites that cause <a href="http://www.who.int/topics/leishmaniasis/en/">leishmaniasis</a>.</p></li>
</ul>
<p>Ironically, it is low-energy LED light bulbs that are the <a href="http://www.esajournals.org/doi/full/10.1890/14-0468.1">most attractive</a> due to the fact that they emit more blue light. This is such a major issue that attempts are underway to <a href="http://rstb.royalsocietypublishing.org/content/370/1667/20140125">tune LEDs</a> so that they attract a smaller number of flying insects.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/101031/original/image-20151106-16239-1y53v0s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/101031/original/image-20151106-16239-1y53v0s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/101031/original/image-20151106-16239-1y53v0s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/101031/original/image-20151106-16239-1y53v0s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/101031/original/image-20151106-16239-1y53v0s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/101031/original/image-20151106-16239-1y53v0s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/101031/original/image-20151106-16239-1y53v0s.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">
<figcaption>
<span class="caption">Blue light
that attracts vector carrying flying insects.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Artificial light + human odours + evolution = trouble</h2>
<p>Mosquitoes are not just attracted to light. They also seek out human skin due to the <a href="http://link.springer.com/article/10.1007%2Fs10886-014-0542-x">CO2</a> released by our bodies when we breathe, and are attracted to <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0015829">chemicals</a> released by skin bacteria. </p>
<p>Historically, this may not have been a major issue because mosquitoes tend to feed after midnight. But mosquito populations may have evolved to seek blood-meals <a href="http://www.sciencedirect.com/science/article/pii/S0001706X15300577">earlier in the night</a> due to the selective pressure of bed nets. In addition, the <a href="http://www.ncbi.nlm.nih.gov/pubmed/25597498">efficiency</a> of transmission from humans to mosquitoes may have increased over recent decades. This again is due to the pressure of control measures against the parasite.</p>
<p>So what might happen if the introduction of artificial light, using low-energy LEDs, is combined with other interventions?</p>
<p>Research is still at an early stage. On the one hand, <a href="http://www.malariajournal.com/content/14/1/209">modern housing</a> may reduce the risk of malaria. But there is already some epidemiological evidence that electrification of community buildings and neighbourhoods may accidentally <a href="http://trstmh.oxfordjournals.org/content/104/1/61.long">increase the risk of malaria</a> and <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2974685/">other diseases</a>. </p>
<p>Some of these effects may be directly as a result of lights attracting vectors of disease to places where humans are present. Alternatively, the vectors may not be attracted to light itself but to humans who are undertaking domestic and economic activities near to a source of artificial light. This may be happening even as the harmful effects of particulates from kerosene lamps are reduced. </p>
<h2>Joining the dots</h2>
<p>To find solutions to this double-edged sword we can first turn to the field of <a href="http://www.biomedcentral.com/1741-7015/11/116">Evolutionary Medicine</a>. This considers how evolutionary processes shape our ability to combat disease. Research in this field can be combined with an integrated approach involving <a href="https://theconversation.com/an-integrated-sustainable-fix-is-key-to-solving-africas-energy-woes-48256">sustainable buildings</a>, and <a href="http://www.sciencedirect.com/science/article/pii/S2214629614001431">sociotechnical</a> research to tackle both energy and health issues simultaneously. </p>
<p>At the heart of that idea is the fact that solar power, when integrated into modern, energy-efficient buildings, can be used entirely off grid to bring electricity to <a href="http://app-cdn.acwupload.co.uk/wp-content/uploads/2015/06/APP_REPORT_2015_FINAL_low1.pdf">hundreds of millions</a> of people in Africa who lack access to energy. Many of these people live in areas where vector borne diseases are common.</p>
<p>Such an integrated approach needs careful planning and will not provide solutions at the same pace as providing small-scale solar systems to individual householders. This is probably why DFID is now behind small-scale solar. The technology has overcome historic barriers of affordability, availability and energy storage and can be installed into otherwise unimproved residences.</p>
<p>DFID is keen to open up the market to businesses in the solar sector. I am keen to ensure that the evidence base keeps on building so that the public, private and civil sectors are informed about the consequences and impact of their activities. </p>
<p>More generally, forewarned is forearmed, and by conducting research and examining the evidence ahead of wide-scale implementation, we can generate testable hypotheses and combine basic, applied, operational and implementation research to greater effect.</p><img src="https://counter.theconversation.com/content/49838/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mark Booth 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>Solar is a vital piece of the energy puzzle for Africa, but there is an insect problem that comes with the light from solar.Mark Booth, Senior Lecturer in Epidemiology, Durham UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/240722014-04-30T20:29:54Z2014-04-30T20:29:54ZBites and parasites: vector-borne diseases and the bugs spreading them<figure><img src="https://images.theconversation.com/files/46970/original/yxcr4sn4-1398315659.jpg?ixlib=rb-1.1.0&rect=0%2C57%2C640%2C371&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Vector-borne diseases are responsible for 17% of all infectious diseases.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/agder/2783124139/in/photolist-6LcRcD-ftZoHn-5eWeQX-JsZYL-nCeRX-hKEnK5-xsPhW-4YRM2y-wLTWG-nCeRT-fQnZtM-fkFDMt-mAtMwr-5W2ABv-7ks3oF-2XnV3-g62PA-kETfQK-fpNBZL-7iZSB-fSS2Qr-fSS3v5-6aZn7R-kUTd1-vMPGS-fQnZng-6APinT-5vZWe-3crN6x-6TaLXN-e5znsu-dL2Wn-5f7FGA-g4EaCh-gTXJFu-8roaxA-gakv7b-tJYHw-dY2U27-7Jo2qm-fQnYZz-bVjH82-bupt7S-7uEr1b-6dh4k6-7RY1TQ-rnzy9-93T2e4-dfFvP-jEboS">dr_relling/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>The term “vector-borne” refers to the way diseases are passed on from one person to another. Instead of through the air or directly by human contact, these pathogens need to hitch a ride for transmission. Vectors are any organisms that carry disease-causing pathogens from host to host.</p>
<p>Vector-borne diseases are responsible for 17% of all infectious diseases; they cause a staggering one billion deaths each year.</p>
<h2>Mosquitoes, ticks and parasites</h2>
<p>The most obvious vectors are mosquitoes. These “shared syringes of the natural world” can transmit diseases such as <a href="https://theconversation.com/explainer-what-is-ross-river-virus-24630">Ross River fever</a>, <a href="http://www.who.int/mediacentre/factsheets/fs094/en/">malaria</a> or <a href="https://theconversation.com/explainer-what-is-dengue-fever-8571">dengue</a>. </p>
<p>But menace doesn’t just lurk in the air; other nasties are involved as well. </p>
<p>Many people will have heard of <a href="http://en.wikipedia.org/wiki/Lyme_disease">Lyme disease</a> being transmitted by ticks. Some ticks in Africa, the Middle East and the Caucasus can also transmit a virus that causes an often deadly haemorrhagic fever, known as the <a href="http://www.who.int/mediacentre/factsheets/fs208/en/">Crimean-Congo haemorrhagic fever</a>.</p>
<p>In parts of Africa and some regions in Asia and South America, contact with water can mean infection with parasitic worms that cause the disease <a href="http://www.who.int/mediacentre/factsheets/fs115/en/">schistosomiasis</a>. This chronic infection kills an estimated 200,000 people a year and has a great impact on affected economies. </p>
<p>The vectors of <em>Schistosoma</em> worms are aquatic snails. When someone is infected with the worm, her stool will contain worm eggs. And when sewage comes into contact with freshwater, the eggs will develop into larvae and multiply inside snails, changing their form. The changed larvae are extremely infective to humans. They escape from the snails into the water and if you happen to wade through this particular pool, the larvae will attach and bore through your skin.</p>
<p>In the Americas, triatomine bugs carry the parasite causing <a href="http://www.who.int/mediacentre/factsheets/fs340/en/">Chagas disease</a>. These “kissing bugs” live in crevices of the wall and roofs of houses. At night, they suck blood from sleeping humans, preferring the face (the “kiss” of the bug). </p>
<p>The parasites in the bug’s faeces are left on the skin when the bug defecates after a blood meal. Scratching of the bite during the next days allows the parasites to enter the wound. </p>
<p>Chronic Chagas disease can lead to life-threatening heart and digestive disorders. There is a theory that even Charles Darwin himself suffered from this unpleasant souvenir of his travels.</p>
<p>In terms of deadliness, there’s one vector-borne disease that stands out. Malaria causes an estimated 660,000 deaths every year; most of those killed are African children under five years of age. The economic impact of the disease is enormous. </p>
<p>Malaria parasites are especially known for their ability to become immune against drugs. <a href="https://theconversation.com/parasite-resistance-imperils-our-last-effective-malaria-drug-21685">Drug-resistant malaria</a> strains are a major worry for global health. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/46446/original/hkm677cq-1397543383.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/46446/original/hkm677cq-1397543383.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/46446/original/hkm677cq-1397543383.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=485&fit=crop&dpr=1 600w, https://images.theconversation.com/files/46446/original/hkm677cq-1397543383.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=485&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/46446/original/hkm677cq-1397543383.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=485&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/46446/original/hkm677cq-1397543383.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=609&fit=crop&dpr=1 754w, https://images.theconversation.com/files/46446/original/hkm677cq-1397543383.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=609&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/46446/original/hkm677cq-1397543383.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=609&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>
</figcaption>
</figure>
<h2>Deadly but neglected</h2>
<p>Many vector-borne diseases fall into the category of illnesses called <a href="https://theconversation.com/neglected-diseases-stunt-progress-as-well-as-the-body-23271">neglected tropical diseases</a>. They have a major impact on the lives of millions of people. </p>
<p>But since these people live in the usually poor, tropical regions of our planet, we don’t hear very much about it. Lack of awareness and a low market value also mean there’s only very little funding for research into those diseases.</p>
<p>And there’s another complication. With the changes in our climate, the distributions of vectors around the world are shifting. </p>
<p>A <a href="http://www.independent.co.uk/news/science/climate-change-is-increasing-the-risk-of-malaria-for-people-living-in-mountainous-regions-in-the-tropics-9174448.html">recent study</a> on malaria in Ethiopia and Colombia showed malaria infections are moving to higher altitudes. </p>
<p>Disease-transmitting ticks in Europe are now found further north than previously. Lower winter temperatures lead to <a href="http://www.sciencedirect.com/science/article/pii/S1438422108000295">ticks being active during winter</a> instead of lying dormant, waiting for spring.</p>
<p>At the same time, new vectors are appearing and spreading. Aedes albopictus, the vector for dengue and <a href="https://theconversation.com/explainer-the-chikungunya-virus-and-its-risk-to-australia-16968">chikungunya</a>, was <a href="http://www.ecdc.europa.eu/en/publications/publications/0905_ter_development_of_aedes_albopictus_risk_maps.pdf">accidentally imported to Italy in 1990</a>. The larvae were hiding in tiny remnants of water inside old tyres. Those mosquitoes have now spread through most of the Mediterranean region and have been even found as far north as the Netherlands. </p>
<p>Milder winters allow this subtropical insect to remain in Europe. So far dengue and chikungunya are still rare there and are only linked to disease imported from other countries. But the risk of the mosquito spreading and getting established is high, and the situation is being carefully watched.</p>
<p>Other changes in the environment are also playing a role. Deforestation and loss of monkey habitat has been suggested as one of the reasons why <a href="http://www.nimr.mrc.ac.uk/mill-hill-essays/plasmodium-knowlesi-malaria-infections-in-malaysia-the-last-parasite-standi">infections with monkey malaria in Asia</a> are now more common.</p>
<p>So what can be done?</p>
<p>Even though funding is poor, there is research into these diseases and some new drugs are being tested. Many not-for-profit initiatives such as the <a href="http://www.gatesfoundation.org/">Bill & Melinda Gates Foundation</a>, <a href="http://www.end7.org/">End7</a> and <a href="http://www.mmv.org/">Medicines for Malaria Venture</a> are seeking to raise awareness for diseases and to effectively link academic research with industry to develop the best drugs.</p>
<p>The most efficient way of combating vector-borne diseases is targeting their vectors. The United States managed to eradicate malaria 50 years ago by following through with widespread campaigns of mosquito eradication. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/y68F8YwLWdg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Disney’s seven dwarves help malaria eradication efforts.</span></figcaption>
</figure>
<p>Even Disney’s seven dwarfs helped out, though I wouldn’t recommend their approach of just adding oil to swamps today.</p>
<p>Insecticide-treated bed nets protect people during the night and are being distributed to even the poorest areas. And better sanitation in developing countries is important to help stop the spread of diseases. </p>
<p>If you are planning on travelling to the subtropical or tropical regions of this planet, make sure you take the available prophylaxis and vaccines against any diseases in that region. And while at home, be aware of mosquito-borne diseases and use <a href="https://theconversation.com/aussies-vs-mozzies-a-users-guide-to-repellents-10964">mosquito repellent</a>. </p><img src="https://counter.theconversation.com/content/24072/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Simona John von Freyend 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 term “vector-borne” refers to the way diseases are passed on from one person to another. Instead of through the air or directly by human contact, these pathogens need to hitch a ride for transmission…Simona John von Freyend, Research Fellow, Malaria biochemistry, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.