tag:theconversation.com,2011:/au/topics/chikungunya-7134/articlesChikungunya – The Conversation2024-03-19T12:23:24Ztag:theconversation.com,2011:article/2237062024-03-19T12:23:24Z2024-03-19T12:23:24ZFemale mosquitoes rely on one another to choose the best breeding sites − and with the arrival of spring, they’re already on the hunt<figure><img src="https://images.theconversation.com/files/582309/original/file-20240315-26-7bf0sq.jpg?ixlib=rb-1.1.0&rect=30%2C0%2C6789%2C4468&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">_Aedes aegypti_, found across much of the U.S., spread Zika, dengue, chikungunya and other viruses.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/aedes-aegypti-mosquito-pernilongo-with-white-spots-royalty-free-image/1282216815">Mailson Pignata/iStock via Getty Images</a></span></figcaption></figure><p><em>Aedes aegypti</em> mosquitoes, one of the <a href="https://www.cdc.gov/mosquitoes/mosquito-control/professionals/range.html">most common species in the U.S.</a>, love everything about humans. They love our <a href="http://dx.doi.org/10.1126/science.adi8213">body heat and odors</a>, which enable them to find us. They love to feed on our blood to make their eggs mature. They even love all the standing water that we create. Uncovered containers, old tires and junk piles collect water and are perfect for breeding. </p>
<p>And with the advent of warm weather across the southern U.S., <a href="https://www.mosquitomagnet.com/articles/mosquito-season">mosquito breeding season is already underway</a>.</p>
<p>Given all the options that <em>Aedes</em> females have in urban areas, how do these cosmopolitan mosquitoes find the perfect site to lay their eggs? Scientists previously thought this was a solitary act, but now research shows that female <em>Aedes aegypti</em> mosquitoes – the main vector in the U.S. for diseases such as <a href="https://theconversation.com/explainer-where-did-zika-virus-come-from-and-why-is-it-a-problem-in-brazil-53425">Zika, dengue, chikungunya</a> and other viruses – can rely on one another for good reviews of breeding sites. </p>
<p>Our <a href="https://www.degennarolab.org/">Laboratory of Tropical Genetics</a> at Florida International University discovered a new behavior in which these mosquitoes <a href="https://doi.org/10.1038/s42003-024-05830-5">work together to find suitable egg-laying sites</a>. These findings, recently published in Communications Biology, show that mosquitoes regulate their own population density at breeding sites – an insight that could inform future mosquito control efforts.</p>
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<a href="https://images.theconversation.com/files/581972/original/file-20240314-30-jxgzpm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A half-dozen mosquitoes spread along the inside of a container." src="https://images.theconversation.com/files/581972/original/file-20240314-30-jxgzpm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/581972/original/file-20240314-30-jxgzpm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=750&fit=crop&dpr=1 600w, https://images.theconversation.com/files/581972/original/file-20240314-30-jxgzpm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=750&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/581972/original/file-20240314-30-jxgzpm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=750&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/581972/original/file-20240314-30-jxgzpm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=943&fit=crop&dpr=1 754w, https://images.theconversation.com/files/581972/original/file-20240314-30-jxgzpm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=943&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/581972/original/file-20240314-30-jxgzpm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=943&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"><em>Aedes aegypti</em> female mosquitoes laying their eggs in a laboratory breeding container.</span>
<span class="attribution"><span class="source">Kaylee Marrero</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<h2>Where and why female mosquitoes cluster</h2>
<p>Scientists know that female mosquitoes can be picky when it comes to where they lay their eggs. <em>Aedes aegypti</em> look for human-made breeding sites with relatively clean water, such as birdbaths, tires or even water-filled trash. But given two equal choices, you might expect them to spread evenly between the two. </p>
<p>On the contrary, when we released females in a two-choice test where both breeding site options were equivalent, we repeatedly found more mosquitoes in one chamber than in the other. Furthermore, this occurred irrespective of where the preferred chamber was positioned, whether the mosquitoes could touch water or whether mosquito eggs were already present at the breeding sites. </p>
<p>Female mosquitoes clearly were following one another in small groups to one breeding site rather than another – a newly discovered behavior in <em>Aedes aegypti</em> that we call aggregation. </p>
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<a href="https://images.theconversation.com/files/581971/original/file-20240314-26-70qvqk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two ramekins, one with a few black spots in it, the other with many spots." src="https://images.theconversation.com/files/581971/original/file-20240314-26-70qvqk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/581971/original/file-20240314-26-70qvqk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=319&fit=crop&dpr=1 600w, https://images.theconversation.com/files/581971/original/file-20240314-26-70qvqk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=319&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/581971/original/file-20240314-26-70qvqk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=319&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/581971/original/file-20240314-26-70qvqk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=401&fit=crop&dpr=1 754w, https://images.theconversation.com/files/581971/original/file-20240314-26-70qvqk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=401&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/581971/original/file-20240314-26-70qvqk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=401&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">The black spots in the container on the right indicate that <em>Aedes aegypti</em> females have chosen it as a place to lay their eggs over the identical site on the left.</span>
<span class="attribution"><span class="source">Kaylee Marrero</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>The insects evidently preferred not to lay their eggs alone. When we tested 30 mosquitoes in our trials, they chose one site over another by a 2-to-1 margin. However, this changed as the test population increased beyond 30 mosquitoes. When we tested 60 or 90 females, the aggregation disappeared.</p>
<p>This tells us that females can regulate their own density at breeding sites – a response that likely is a mechanism to limit larval competition.</p>
<h2>Mosquitoes are smelling each other</h2>
<p>Mosquitoes largely sense the world through smell, using three families of <a href="https://www.britannica.com/science/olfactory-receptor">olfactory receptors</a>. These receptors detect odors when females are choosing where to lay eggs. But how do females sense each other to regulate their densities at breeding sites? </p>
<p>We explored this question by first placing 15 mosquitoes at one of our two test breeding sites. Other females seeking a place to lay preferred the unoccupied site over the one that was already occupied, even though we had already observed that the mosquitoes preferred not to lay their eggs alone. Something was directing them away from the occupied breeding site; we speculated that it might be carbon dioxide, which is an important cue for mosquitoes in all stages of their life cycle. </p>
<p>When female mosquitoes are looking for a blood meal, they fly toward the odor of CO₂, which all vertebrate animals <a href="https://theconversation.com/why-are-some-people-mosquito-magnets-and-others-unbothered-a-medical-entomologist-points-to-metabolism-body-odor-and-mindset-187957">exhale and release through their skin</a>. After feeding, they fly away from it, likely to avoid the risk of being killed by the host. </p>
<p>Mosquitoes also emit CO₂, and normally other mosquitoes can smell it, thanks to a receptor component called Gr3 in their olfactory organs. But when we released mutant females that lacked a functional Gr3 receptor to seek a place to lay eggs in our two-site test, we found that these insects, which could not detect CO₂, were willing to lay their eggs at preoccupied breeding sites. This suggested that normal mosquitoes might be avoiding the preoccupied laying site because they smelled CO₂ emitted by mosquitoes that were already there.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/EUrOcquy8IU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Female mosquitoes lay eggs on or near still bodies of water.</span></figcaption>
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<p>To confirm this, we offered two unoccupied breeding sites to females seeking a place to lay. However, we increased CO₂ levels around one of the sites to between 600 and 750 parts per million, compared with the normal level of about 450 to 500 ppm at the other site. We found that <em>Aedes aegypti</em> females avoided the unoccupied sites with elevated CO₂. This behavior appears designed to keep occupied breeding sites from becoming too crowded. </p>
<p>Overall, we found that two families of receptors play a role in the interactions between <em>Aedes aegypti</em> females when they seek breeding sites. Odorant receptors detect an unknown odor, which draws females toward a site; gustatory receptors detect CO₂, which deters females from breeding sites when the carbon dioxide level is high. The balance between these attractive and repellent odors will ultimately determine whether a female chooses or avoids a particular site. </p>
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<a href="https://images.theconversation.com/files/582583/original/file-20240318-20-i9yyck.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Graphic showing common mosquito breeding sites around home, including gutters and pet dishes." src="https://images.theconversation.com/files/582583/original/file-20240318-20-i9yyck.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/582583/original/file-20240318-20-i9yyck.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/582583/original/file-20240318-20-i9yyck.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/582583/original/file-20240318-20-i9yyck.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/582583/original/file-20240318-20-i9yyck.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/582583/original/file-20240318-20-i9yyck.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/582583/original/file-20240318-20-i9yyck.jpeg?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>
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<span class="caption">Mosquitoes breed in many wet spots, large and small.</span>
<span class="attribution"><a class="source" href="https://www.cabq.gov/environmentalhealth/urban-biology/mosquitoes">City of Albuquerque</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<h2>Implications for mosquito control</h2>
<p>Suppressing mosquito populations in urban areas using <a href="https://www.cdc.gov/mosquitoes/mosquito-control/community/larvicides.html">biolarvicides</a> – pesticides made from live bacteria that are toxic to mosquito larvae – is a primary control strategy to limit the spread of deadly diseases such as West Nile virus and Zika virus. This is especially true for <em>Aedes aegypti</em>, which is the most common urban mosquito species that reproduces in artificial breeding sites that humans create. Other control tactics, such as <a href="https://undark.org/2019/10/25/when-residents-say-no-to-aerial-mosquito-spraying/">spraying pesticides over large areas</a>, target beneficial insects as well as mosquitoes and can be controversial. </p>
<p>Knowing that female <em>Aedes aegypti</em> use social cues to pick the best breeding grounds for their young and will move on from a breeding site when it becomes too crowded could lead to new control measures. Interrupting the female mosquito reproductive cycle would reduce the spread of mosquitoes and the spread of diseases that these insects carry.</p><img src="https://counter.theconversation.com/content/223706/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kaylee Marrero receives funding from the National Institutes of Health.</span></em></p><p class="fine-print"><em><span>Andre Luis Costa-da-Silva receives funding from the Centers for Disease Control and Prevention, the Southeastern Center of Excellence in Vector-borne Disease and the National Institutes of Health. Views expressed in this article are his own. </span></em></p><p class="fine-print"><em><span>Matthew DeGennaro receives funding from the Centers for Disease Control and Prevention (CDC), the Southeastern Center of Excellence in Vector-borne Disease and the National Institutes of Health. Views expressed in this article are his own.</span></em></p>Female mosquitoes don’t want to lay their eggs alone, but they don’t want sites that are too crowded either. Understanding what guides their choice could inform new control strategies.Kaylee Marrero, Ph.D. Student and Transdisiplinary Biomolecular and Biomedical Sciences Fellow, Florida International UniversityAndre Luis da Costa da Silva, Research Assistant Professor of Biological Sciences, Florida International UniversityMatthew DeGennaro, Associate Professor of Biological Sciences, Florida International UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2221272024-01-29T13:09:18Z2024-01-29T13:09:18ZNeglected tropical diseases persist in the world’s poorest places: four reads about hurdles and progress<p>It’s sobering to reflect that “neglected tropical diseases” are referred to as “neglected” because they persist in the poorest, most marginalised communities even after being wiped out in more developed parts of the world.</p>
<p>A variety of pathogens, including viruses, bacteria, parasites, fungi and toxins, cause neglected tropical diseases, which include dengue, chikungunya, leprosy, lymphatic filariasis and yaws.</p>
<p>They inflict tremendous suffering because of their disfiguring, debilitating and sometimes deadly impact. Patients often experience stigma, social exclusion and superstition. </p>
<p>The good news is that there is reason for hope as some African countries have made significant progress in eradicating these diseases. </p>
<p>We have put together some essential reads from The Conversation Africa over the past year highlighting a scourge that still affects more than <a href="https://www.who.int/news-room/questions-and-answers/item/neglected-tropical-diseases#:%7E:text=It%20is%20estimated%20that%20NTDs,often%20related%20to%20environmental%20conditions.">1 billion people </a> today. </p>
<h2>Patients’ beliefs about illness matter</h2>
<p>Would you take medication for an illness you didn’t believe you had? Or if you disagreed with healthcare workers about the cause of your condition?</p>
<p>This is the dilemma of many people who live in rural areas of Ghana where a mosquito-borne disease called lymphatic filariasis, often referred to as elephantiasis, continues to spread. Researchers found that only 18% of respondents understood lymphatic filariasis as a disease. Fewer than 7% believed it to be a disease spread by mosquitoes.</p>
<p>Instead, people held a range of alternative beliefs attributing the condition to spiritual causes (curses, witchcraft, evil spirits), cold or rainy weather, and other illnesses.</p>
<p>The team of experts, that carried out the research, suggest that understanding patients’ belief systems would help healthcare workers treat patients more effectively. </p>
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Read more:
<a href="https://theconversation.com/patients-beliefs-about-illness-matter-the-case-of-elephantiasis-in-rural-ghana-216838">Patients' beliefs about illness matter: the case of elephantiasis in rural Ghana</a>
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<h2>100 million Nigerians are at risk</h2>
<p>A quarter of the people affected by neglected tropical diseases in Africa live in Nigeria. An estimated 100 million Nigerians are at risk for at least one of these diseases and there are several million cases of people being infected with more than one of them.</p>
<p>There has been progress, writes Uwem Friday Ekpo. By January 2023 the country had eradicated Guinea worm disease and two states had eliminated onchocerciasis. </p>
<p>One of the interventions was door-to-door visits by volunteers to administer medicines. Teachers also played a similar role when medicines were distributed in schools. </p>
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Read more:
<a href="https://theconversation.com/100-million-nigerians-are-at-risk-of-neglected-tropical-diseases-what-the-country-is-doing-about-it-198320">100 million Nigerians are at risk of neglected tropical diseases: what the country is doing about it</a>
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<h2>Leprosy, scabies and yaws: Togo’s neglected skin diseases</h2>
<p>Skin conditions caused by some bacteria, viruses, mosquitoes or mites are common neglected tropical diseases. </p>
<p>Research in schools and rural areas in Togo, west Africa, found a large number of these infections including scabies, leprosy, yaws and Buruli ulcer.</p>
<p>These are stigmatised and can be difficult to diagnose. There are typically few, if any, dermatologists in areas where they are common. Children with these diseases often refuse to go to school. </p>
<p>Michael Head, Bayaki Saka and Palokinam Pitche suggest authorities make the treatment of these diseases free of charge. Health promotion and education are also critical.</p>
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Read more:
<a href="https://theconversation.com/leprosy-scabies-and-yaws-togos-neglected-tropical-skin-diseases-need-attention-201301">Leprosy, scabies and yaws - Togo's neglected tropical skin diseases need attention</a>
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<h2>Reasons for hope</h2>
<p>Togo did have reason to celebrate though. In 2022 it became the first country in the world to have eliminated four neglected tropical diseases. The country stamped out Guinea worm disease in 2011, lymphatic filariasis in 2017, sleeping sickness in 2020 and trachoma in 2022.</p>
<p>It achieved its milestone through a combination of measures. These included door-to-door mass drug administration, training of healthcare staff, sustained financing and strong political support.</p>
<p>Other African countries also made significant progress in tackling neglected tropical diseases in 2022. Benin, Rwanda and Uganda managed to eliminate sleeping sickness. Malawi eliminated trachoma and the Democratic Republic of Congo eliminated Guinea worm disease.</p>
<p>But the global health community and African governments cannot rest on their laurels. There is still a long way to go, writes Monique Wasunna. </p>
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Read more:
<a href="https://theconversation.com/eliminating-neglected-diseases-in-africa-there-are-good-reasons-for-hope-198543">Eliminating neglected diseases in Africa: there are good reasons for hope</a>
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Neglected tropical diseases are often associated with social exclusion as well as physical suffering. One billion people around the world suffer from these diseases.Nadine Dreyer, Health & Medicine EditorLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1391292020-05-26T14:17:09Z2020-05-26T14:17:09ZLockdown and flooding raise the risk of a spike in mosquito-borne diseases in Kenya<figure><img src="https://images.theconversation.com/files/336741/original/file-20200521-102632-3fbfz3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A family sitting under a treated mosquito net.</span> <span class="attribution"><span class="source">GettyImages</span></span></figcaption></figure><p>As soon as the first case of COVID-19 was confirmed in Kenya, the government banned public gatherings of more than 15 people. Schools, colleges and universities were <a href="https://www.aljazeera.com/news/2020/03/kenya-bans-public-events-case-coronavirus-200313101019200.html">closed </a>. Within two weeks, the whole country was placed under a <a href="https://www.theeastafrican.co.ke/news/ea/Kenya-goes-into-dusk-to-dawn-curfew/4552908-5506824-9plkom/index.html">dusk to dawn curfew</a>. Movement in and out of the cities of Mombasa and Nairobi was restricted. Those not in essential services were encouraged to <a href="https://www.aljazeera.com/news/2020/04/covid-19-kenya-bans-travel-nairobi-areas-200406163601579.html">work from home</a> and international flights were <a href="https://www.nation.co.ke/news/Covid-19--State-extends-ban-on-international-flights/1056-5515262-i22m9y/index.html">banned</a>. </p>
<p>Many of these measures could affect the country’s ability to keep mosquito-borne diseases under control. And the restrictions have coincided with the long rainy season in Kenya. Rain increases mosquito breeding sites, vector density and thus transmission of mosquito-borne diseases. Some of the regions currently experiencing high rainfall are the same ones that are prone to mosquito-borne diseases. </p>
<p>For example, areas around Lake Victoria are endemic for <em>Anopheles sp</em> transmitted malaria, which usually spikes in the rainy season. The semi-arid counties like Pokot and Baringo are known for malaria spikes as well as outbreaks of Rift Valley fever, which is transmitted by flood water mosquitoes. </p>
<p>At the coast, outbreaks of dengue and chikungunya fevers transmitted by <em>Aedes aegypti</em> are also associated with the rainy season. Parts of Mombasa county, a malaria endemic zone that also recorded <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5082659/">dengue outbreaks</a> in recent years, are under lockdown, like the <a href="https://www.nation.co.ke/counties/mombasa/Old-Town-now-locked-down/1954178-5544852-kyqx4l/index.html">Old Town area</a>. </p>
<p>There is particular concern about the confluence of these factors on malaria. The World Health Organisation’s modelling and simulations <a href="https://www.who.int/publications-detail/the-potential-impact-of-health-service-disruptions-on-the-burden-of-malaria">show</a> that COVID-19 is likely to affect the fight against the disease. In a worst case scenario, of 75% disruption in the use of insecticide treated bed nets and <a href="https://www.who.int/publications-detail/the-potential-impact-of-health-service-disruptions-on-the-burden-of-malaria">access to treatment</a>, more than 769,000 deaths could be reported in sub-Saharan Africa in 2020. This is double the number of deaths due to malaria in this region in <a href="https://www.who.int/news-room/feature-stories/detail/world-malaria-report-2019">2018</a>. </p>
<h2>Increased risks</h2>
<p>A number of factors related to the lockdown in the country combined with the floods are likely to contribute to a spike in malaria cases.</p>
<p>For example, people are being restricted to particular geographic areas. On top of this, <a href="https://www.kenyanews.go.ke/13300-displaced-in-flood-hit-parts-of-kisumu-county/">flood victims</a> have been converging in localised areas such as primary schools. The restriction of movement and the convergence of people from different areas into a localised place is likely to lead to high transmission of malaria.</p>
<p>A further danger is that COVID-19 could take up precious resources in the healthcare system, reducing the efficacy in handling mosquito-borne diseases like malaria. Unfortunately, the more the number of carriers in the environment, the higher the likelihood of <a href="https://unfoundation.org/blog/post/malaria-and-covid-19-why-we-must-fight-both/">spikes and outbreaks</a>. </p>
<p>Likewise, there might be a reduction in measures – such as cleaning and draining of stagnant bodies of water and larvicide application in breeding sites – that are commonly taken to fight outbreaks of mosquito-borne diseases. This would obviously lead to a high density of vectors and thus extensive transmission. </p>
<p>In addition, there have been reports of people <a href="https://www.kenyanews.go.ke/residents-urged-not-to-shun-hospitals-because-of-coronavirus/">shunning health facilities</a> for fear of getting infected with COVID-19. This may also lead to increases in malaria cases as people avoid seeking treatment. Such a scenario was reported in West and Central Africa during the <a href="https://unfoundation.org/blog/post/malaria-and-covid-19-why-we-must-fight-both/">Ebola epidemic</a>. </p>
<h2>What can be done</h2>
<p>The best strategies to control mosquito-borne epidemics are to reduce the mosquito population and for people to avoid mosquito bites. </p>
<p>Modelling and simulation <a href="https://www.academia.edu/42685010/Lockdowns_to_Contain_COVID-19_Increase_Risk_and_Severity_of_Mosquito-Borne_Disease_Outbreaks?auto=download&campaign=weekly_digest">reports</a> have shown that the most effective mosquito-borne disease control methods during lockdowns are those aimed at protecting localised population densities, like the use of insecticide-treated nets and indoor residual spraying. </p>
<p>This means that Kenya’s national and county governments should double their efforts in encouraging the use of insecticide-treated nets in mosquito-borne disease endemic zones. This should be combined with the distribution of free mosquito nets to homes and camps where displaced people have gathered. </p>
<p>The government should also spray homes and camps. </p>
<p>Additionally, the policy-makers could encourage people to be more proactive in using mosquito repellent creams, liquids, coils and mats in addition to mosquito nets to avoid mosquito bites.</p>
<p>The government must also ensure that malaria drugs are available and easily accessible as they encourage people to seek care for fever and suspected malaria. </p>
<p>Finally, the Kenyan government should seek additional funding. It could do this, for example, by calling on the Roll Back Malaria partners like the Global Fund to Fight AIDS, Tuberculosis and Malaria. These partners halved their 2018–2020 donations towards malaria programmes in <a href="https://www.who.int/en/news-room/feature-stories/detail/in-kenya-the-path-to-elimination-of-malaria-is-lined-with-good-preventions">Kenya</a>.</p><img src="https://counter.theconversation.com/content/139129/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Eunice Anyango Owino receives funding from the National Research Fund (NRF), Kenya.</span></em></p>The pandemic coincides with the long rainy season in Kenya. Rain increases mosquito breeding sites, vector density and thus transmission of mosquito-borne diseases.Eunice Anyango Owino, Medical Entomologist at the School of Biological Sciences, University of NairobiLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1300762020-01-22T14:16:09Z2020-01-22T14:16:09ZHeavy rains put Kenya at risk of mosquito-borne diseases<figure><img src="https://images.theconversation.com/files/310667/original/file-20200117-118327-ga9jvu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mosquito eggs can remain viable for years even in dry conditions and hatch after heavy persistent rains.
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Kenya experienced above-average rainfall since <a href="https://www.standardmedia.co.ke/article/2001351552/rains-to-continue-till-end-year">October 2019</a>, causing <a href="https://citizentv.co.ke/news/kenya-floods-death-toll-hits-132-306249/">landslides</a> and <a href="https://citizentv.co.ke/news/kenya-floods-death-toll-hits-132-306249/">deaths</a>. Some rivers burst their banks and <a href="https://mobile.nation.co.ke/news/Uhuru-Dam-bursts-its-banks/1950946-5373852-t2mq1l/index.html">dams overflowed</a> for the first time in years. </p>
<p>The rains have subsided but the danger isn’t over. There is a likelihood of outbreaks of various mosquito-borne diseases such as <a href="https://www.ncbi.nlm.nih.gov/pubmed/3879206">Rift Valley fever</a>, malaria, dengue and chikungunya fever. Prolonged rains increase the amount of stagnant water in the environment – in which mosquitoes breed. </p>
<p>The meteorological department <a href="https://www.standardmedia.co.ke/article/2001351552/rains-to-continue-till-end-year">attributed</a> the heavy rains experienced in most parts of the country to unusual sea surface temperatures in the Indian, Atlantic and Pacific Oceans. Rains like these were previously associated with <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2913499/">outbreaks</a> of <a href="https://www.ncbi.nlm.nih.gov/pubmed/10411500">Rift Valley fever</a> more than any other disease.</p>
<p>Knowing how mosquito-borne diseases are transmitted to animals and humans can help countries to prevent and cope with outbreaks.</p>
<h2>Rift Valley fever</h2>
<p>Cases of the disease were first reported in the Rift Valley province of Kenya in <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/path.1700340418">1930</a>. It is caused by a virus that infects both livestock and humans. Outbreaks are usually associated with unusually heavy rainfall, extensive flooding of low-lying grassland depressions called dambos and mass emergence of <a href="https://www.ncbi.nlm.nih.gov/pubmed/3879206"><em>Aedes</em> mosquitoes</a>. The mosquitoes deposit their eggs in soil. The eggs can remain viable for years even in dry conditions and hatch after heavy persistent rains. Emerging infected adult female mosquitoes transmit the virus to nearby animals, including sheep, goats, cattle and camels. These in turn infect more mosquitoes. Another group of insects, mainly from the <em>Culex</em>, <em>Anopheles</em> and <em>Mansonia</em> species, may then take over the breeding sites and pass the <a href="https://www.ncbi.nlm.nih.gov/pubmed/28212379">virus</a> to more animals and humans. </p>
<p><a href="https://www.who.int/news-room/fact-sheets/detail/rift-valley-fever">Rift Valley fever</a> causes livestock to abort or die at birth. In humans it causes flu-like illness – and sometimes encephalitis, retinitis and generalised hemorrhagic syndrome. Mosquitoes can transmit Rift Valley fever to humans through bites. But <a href="https://www.who.int/news-room/fact-sheets/detail/rift-valley-fever">studies</a> suggest that severe human infections are a result of direct or indirect contact with blood, secretions or tissue of infected animals. </p>
<p>During the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2913501/">2006-2007</a> outbreak, Kenya suffered losses of $32 million from animal deaths, vaccination costs and impact on trade. More than 150 people died and over 700 were hospitalised. This put a strain on the already overstretched <a href="https://www.ncbi.nlm.nih.gov/pubmed/20682900">public health resources</a>. The <a href="https://www.cdc.gov/mmwr/preview/mmwrhtml/00051976.htm">1997–1998</a> outbreak in East Africa (Kenya, Somalia, and Tanzania) affected over 100,000 people and caused 170 deaths in Kenya. Outbreaks have also been reported in other African and Middle Eastern countries.</p>
<p>In <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2913499/">2006</a>, satellite measurements of global and regional sea surface temperature, elevated rainfall data and the difference in vegetation index data were used to predict the outbreak <a href="https://earthobservatory.nasa.gov/images/37025/predicting-rift-valley-fever">three months</a> before cases were confirmed. Such early warning systems should enable authorities to take action to avert epidemics.</p>
<p>Other measures include controlling mosquito larvae at breeding sites.</p>
<p>Animals can be immunised. Rift Valley fever infection is usually <a href="http://www.ajtmh.org/content/journals/10.4269/ajtmh.2010.09-0292">reported in livestock</a> before humans as animals mainly get infected by mosquito bites while humans get the virus mainly from infected animals. It would help to have an active surveillance system to detect new cases in animals. Livestock movement should be restricted in an outbreak.</p>
<p>Public health education should focus on reducing the risk of transmission from animals to people. This is done by practising hand hygiene and wearing gloves and other protective equipment when handling sick animals. It’s not safe to consume fresh blood, raw milk or animal tissue – these products should be thoroughly cooked first. It’s also advisable to use mosquito nets and insect repellent.</p>
<p>Healthcare workers should be careful when handling patients and their specimens even if a case of Rift Valley fever is not yet confirmed.</p>
<h2>Malaria</h2>
<p>Malaria is a risk to <a href="https://www.who.int/news-room/feature-stories/detail/in-kenya-the-path-to-elimination-of-malaria-is-lined-with-good-preventions">70%</a> of Kenya’s 47.5 million people, especially communities around Lake Victoria and off the coast. In Kenya, it’s mainly caused by the protozoan <em>Plasmodium falciparum</em> transmitted by the <em>Anopheles</em> <a href="https://parasitesandvectors.biomedcentral.com/articles/10.1186/s13071-015-0860-z">species mosquitoes</a>, which breed in swamps that develop during the rainy seasons. But during prolonged rains even areas at higher altitudes are at risk. Malaria outbreaks can be more severe in <a href="https://parasitesandvectors.biomedcentral.com/articles/10.1186/s13071-015-0860-z">highlands</a> because people have not developed immunity against the disease, or aren’t familiar with the symptoms and may go to hospital too late.</p>
<p>To avoid malaria, people need to use mosquito nets and insecticides. Local hospitals should be sure to have stocks of anti-malarial drugs and supplementary food for children under five, who are the most <a href="http://repository.eac.int/bitstream/handle/11671/598/Malaria%20Treatment%20Guidelines.pdf?sequence=1&isAllowed=y">severely affected</a>. </p>
<h2>Dengue and chikungunya fever</h2>
<p>Kenya is one of several countries around the world experiencing unprecedented outbreaks of chikungunya and <a href="http://www.who.int/mediacentre/factsheets/fs117/en/">dengue</a> fever viruses transmitted to humans by the <a href="https://www.ncbi.nlm.nih.gov/pubmed/23701618"><em>Aedes</em> species mosquitoes</a>. The diseases are mainly <a href="https://www.who.int/docs/default-source/searo/myanmar/prevent-dengue-and-chikungunya.pdf?sfvrsn=9b1b3069_0">characterised</a> by fever and severe joint pain.</p>
<p>Regions at highest risks are the coastline, especially the city of <a href="https://www.nation.co.ke/counties/mombasa/Dengue-fever-outbreak-hits-153-in-Mombasa/1954178-3917332-j1c2sj/index.html">Mombasa</a> and the <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0198556">north eastern regions</a> that have reported recurrent outbreaks in recent years.</p>
<p>These two <a href="https://www.ncbi.nlm.nih.gov/pubmed/29360072">viruses</a> have no vaccines or treatment. The only way to prevent and control an outbreak is by controlling mosquitoes. </p>
<p><a href="https://www.ncbi.nlm.nih.gov/pubmed/29284522">Recent research</a> on the <em>Aedes aegypti</em> has shown that it often breeds in garbage (like abandoned car tyres, plastic containers and tins), water containers and shaded areas. Now is a good time to <a href="https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0006570">spray indoors</a> against these mosquitoes and to get rid of garbage that provides breeding sites. People can also drain stagnant water, clear bushes and empty water storage tanks. </p>
<p>As the rains in Kenya subside, it’s important that national and county authorities are well prepared and equipped to prevent illness and deaths that might result from outbreaks of these mosquito borne diseases.</p><img src="https://counter.theconversation.com/content/130076/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Eunice Anyango Owino receives funding from the National Research Fund (NRF) and works at the University of Nairobi.</span></em></p>Prolonged rains increase the amount of stagnant water in the environment in which mosquitoes breed. This increases the risk of mosquito-borne diseases.Eunice Anyango Owino, Medical Entomologist at the School of Biological Sciences, University of NairobiLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1234032019-09-16T08:17:33Z2019-09-16T08:17:33ZEthiopia must do more to stop recurring chikungunya outbreaks<figure><img src="https://images.theconversation.com/files/292215/original/file-20190912-190016-1intkd2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A female Aedes albopictus mosquito feeding on a human host.</span> <span class="attribution"><a class="source" href="https://phil.cdc.gov/Details.aspx?pid=4488">James Gathany/CDC </a></span></figcaption></figure><p><em>Ethiopia’s second largest city, Dire Dawa, is dealing with a chikungunya fever outbreak. Around <a href="http://outbreaknewstoday.com/ethiopia-chikungunya-outbreak-reaches-20000-cases-76416/">20,000</a> cases of the mosquito-borne viral infection have been reported since the outbreak started in <a href="https://7dnews.com/news/ethiopia-announces-outbreak-of-chikungunya-in-afar-state">March 2019</a>. This is the second recorded outbreak of the disease in the country; the first was in <a href="https://academic.oup.com/ve/article/5/Supplement_1/vez002.034/5552916">2016</a>. Eunice Anyango Owino spoke to The Conversation Africa about the disease and the burden it places on public health.</em></p>
<p><strong>What is chikungunya?</strong></p>
<p>Chikungunya was first discovered in <a href="https://www.who.int/news-room/fact-sheets/detail/chikungunya">1952</a> along the border between Mozambique and Tanzania. The disease is caused by the <a href="https://www.microbiologyresearch.org/content/journal/jgv/10.1099/0022-1317-81-2-471">chikungunya</a> virus, which is transmitted mainly by mosquitoes in the <em>Aedes</em> family.</p>
<p>Infection can cause severe illness especially in young children, the elderly and people whose immunity has been compromised because they’re suffering from or recovering from other illnesses. <a href="https://www.cdc.gov/chikungunya/symptoms/index.html">Symptoms</a> include joint and muscle pain, fever, headache, fatigue and rash. </p>
<p>While most infections are not life-threatening, cases of mother-to-child transmission of the virus were reported following the <a href="https://insights.ovid.com/crossref?an=00006454-200709000-00008">2006</a> outbreak on Réunion Island. And this is life threatening since babies are among the high risk groups. Some people also died during that outbreak, and deaths have been <a href="http://www.ajtmh.org/docserver/fulltext/14761645/77/4/0770727.pdf?expires=1568185152&id=id&accname=guest&checksum=4C3A941F01ECD65D89646180BDAB1AF8">reported</a> in previous outbreaks in East Africa. </p>
<p>Currently, there is no licensed vaccine or treatment. The only thing that can be done is to relieve the symptoms. This means vector control – getting rid of the mosquitoes that carry the virus – is the main method to deal with outbreaks.</p>
<p><strong>What’s being done to handle the situation in Ethiopia?</strong></p>
<p>An <a href="https://www.ezega.com/News/NewsDetails/7201/Chikungunya-Outbreak-Sweeps-Dire-Dawa-City-in-Ethiopia">indoor residual spray</a> campaign is currently underway in Dire Dawa, the epicentre of the epidemic.</p>
<p>The government is distributing bed nets that have been treated with insecticide and encouraging people to drain open stored rain water as mosquitoes lay their eggs in stagnant water. <em>Aedes aegypti</em> particularly breeds in containers that hold water, especially in developing countries where sanitation and hygiene is not adequate. Previous <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4576013/">studies</a> in the city of Dire Dawa showed that high populations of <em>Ae. aegypti</em> are maintained throughout the year by artificial breeding sites provided by used tyres and containers that hold water, like barrels, plastic drums and jerrycans. </p>
<p>The public has also been advised to be alert and to visit health facilities when symptoms occur. </p>
<p><strong>Do you think this is enough? Should the government be doing more?</strong></p>
<p>The problem with the spraying campaign is that it’s reactive. That makes it less effective than proactive, preventative campaigns would be. For spraying to be effective, it should happen throughout the year, whether there is an outbreak or not.</p>
<p>Authorities also need to intensify awareness campaigns. Perhaps regular health promotion messages could be delivered on local television and radio channels, to reach more people.</p>
<p>Affected communities should be mobilised to institute control measures. That includes covering water collection containers, proper waste disposal and improved environmental sanitation. Similarly, residents should be advised to put on clothing that minimises the exposure of their skin during the day. Repellents could be applied to exposed skin or to clothing.</p>
<p>These are short-term plans the Ethiopian government can put in place to control the spread of the current outbreaks. But long–term plans are also necessary to prevent future outbreaks.</p>
<p><strong>What might those plans look like?</strong></p>
<p>Most Dire Dawa residents store tap and rain water in containers for domestic use. The government needs to supply adequate clean tap water so that this sort of storage isn’t necessary.</p>
<p>In fact, the government must invest more broadly in proper city planning. Urbanisation and population growth are two of the factors that play a role in the increase of outbreaks of arboviral diseases in developing countries; these are viral diseases that spread to people through the bite of infected insects such as mosquitoes or ticks. Ethiopia’s current city infrastructure and facilities are overwhelmed with swelling populations. </p>
<p>Authorities should initiate cross-border surveillance and prevention efforts to avoid the risk of importation. The first chikungunya outbreak in Ethiopia in <a href="https://www.researchgate.net/publication/328412296_The_First_Laboratory_Confirmation_of_Chikungunya_Outbreak_in_Ethiopia">2016</a> is believed to have been imported from the neighbouring Mandera county in Kenya. This, in turn, was imported from Somalia’s Bulahawa region. </p>
<p>Another really important approach is to invest in broad surveillance. Surveillance data can help in preparedness, especially if vector control methods like indoor residual spraying are to be effectively applied, in the right places and at the right time of year.</p><img src="https://counter.theconversation.com/content/123403/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Eunice Anyango Owino receives funding from the National Research Fund, Kenya (NRF). She is affiliated with the University of Nairobi. </span></em></p>While no deaths have been reported in Ethiopia so far, outbreaks of the mosquito-borne disease spread rapidly and have severe impacts on public health.Eunice Anyango Owino, Medical Entomologist at the School of Biological Sciences, University of NairobiLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/947472018-07-03T01:45:46Z2018-07-03T01:45:46ZHumans are to blame for the rise in dangerous viral infections<p>Today, we hear about dangerous viral infections around the world on a regular basis. Social media and internet access may be an obvious explanation for their seeming increase.</p>
<p>But it doesn’t just seem this way. The number of viruses and the infections they cause are truly increasing. Scientific advances, the way humans live today and virus biology all contribute to the rise of viruses.</p>
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<a href="https://theconversation.com/health-check-when-are-we-most-likely-to-catch-viral-diseases-36555">Health Check: when are we most likely to catch viral diseases?</a>
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<h2>New viruses, all the time</h2>
<p>It seems viral infections are everywhere these days. Starting from January 2018, Nigeria has been experiencing an unusually large outbreak of haemorrhagic fever caused by <a href="http://www.who.int/csr/don/20-april-2018-lassa-fever-nigeria/en/">Lassa virus</a>. There have been more than 400 confirmed infections and 100 deaths to date. </p>
<p>The southern Indian state of Kerala is battling an outbreak of the rare <a href="http://www.who.int/news-room/fact-sheets/detail/nipah-virus">Nipah virus</a>, which causes severe inflammation of the brain and claimed the <a href="https://indianexpress.com/article/india/nipah-death-toll-rises-to-14-in-kerala-two-more-cases-confirmed-5193201/">lives of 14 people</a> in May. </p>
<p>The Brazilian outbreak of viral <a href="http://www.who.int/csr/don/09-march-2018-yellow-fever-brazil/en/">yellow fever</a> that began in late 2017 has moved into highly populated areas near São Paulo and Rio de Janeiro. One-third of the 723 people with confirmed infections have so far died from the illness.</p>
<p>We’re no doubt more aware of such serious diseases after the unprecedented 2014-2016 <a href="https://www.bmj.com/content/352/bmj.i243">Ebola outbreak</a> in West Africa that claimed more than 11,000 lives. And then the 2015-2017 <a href="http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0006007">Zika virus</a> outbreak that closely followed during which 3,500 babies were born with nervous system or eye damage. </p>
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<a href="https://theconversation.com/zika-dengue-yellow-fever-what-are-flaviviruses-53969">Zika, dengue, yellow fever: what are flaviviruses?</a>
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<p>The <a href="http://rstb.royalsocietypublishing.org/content/367/1604/2864">first report</a> of human virus infection was <a href="https://www.wiki.sanitarc.si/1901-walter-reed-proved-finlay-s-theory-yellow-fever-transmitted-aedes-aegypti-mosquito/">yellow fever</a> in the US army at the turn of the 20th century. And now, estimates suggest three to four new species of human viruses are <a href="http://rspb.royalsocietypublishing.org/content/275/1647/2111">found each year</a> and around 250 human virus species are yet to be discovered.</p>
<p>Discovery of a new virus today is complex and requires many steps. Typically, it involves describing its complete genetic code with a combination of intensive molecular sequencing work in the laboratory and computational analyses using enormous reference databases. </p>
<p>Medical epidemiological studies (that look at the distribution of disease) and biological experiments are then needed to understand any virus as a dangerous human pathogen. It may then take some time to link a virus with a particular human disease. </p>
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<a href="https://images.theconversation.com/files/225269/original/file-20180628-112611-10ee357.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/225269/original/file-20180628-112611-10ee357.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/225269/original/file-20180628-112611-10ee357.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/225269/original/file-20180628-112611-10ee357.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/225269/original/file-20180628-112611-10ee357.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/225269/original/file-20180628-112611-10ee357.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/225269/original/file-20180628-112611-10ee357.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/225269/original/file-20180628-112611-10ee357.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>
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<span class="caption">Human parechoviruses were only discovered in the 1950s.</span>
<span class="attribution"><span class="source">from shutterstock.com</span></span>
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<p>For instance, <a href="http://www.health.nsw.gov.au/infectious/factsheets/pages/parechovirus.aspx">human parechoviruses</a> (which can cause severe disease in young children) were discovered in the 1950s. But they were <a href="https://www.ncbi.nlm.nih.gov/pubmed/14769896">only identified</a> as a cause of disease in young children in 2004. And relatively <a href="https://wwwnc.cdc.gov/eid/article/21/7/14-1149_article">large Australian epidemics</a> since 2013 have highlighted their link to a serious sepsis-like illness and potential for developmental complications.</p>
<h2>How humans contribute</h2>
<p>Modern humans contribute to the success of dangerous viruses. A virus replicates only when inside the cell of a living being, and spreads most efficiently when there is contact between two individuals. </p>
<p>The United Nations measures current <a href="https://esa.un.org/unpd/wpp/publications/Files/WPP2017_KeyFindings.pdf">world population growth</a> at more than 1% per year. From the virus’ perspective, potential incubators are increasing. The world’s population is also <a href="https://esa.un.org/unpd/wup/publications/Files/WUP2018-KeyFacts.pdf">urbanising</a>, which means people living in closer proximity, which is conducive to spread of a virus. </p>
<p>Domestic and international mass transport permit viruses to move between regional populations.</p>
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<p>Many dangerous virus infections are zoonoses, which are diseases transmitted to humans from other animals. Bats are a common culprit – one theory is that a <a href="https://www.ncbi.nlm.nih.gov/pubmed/29421321">unique low-grade immune system</a> allows them to carry a relatively high number of viruses without developing disease. Epidemics caused by severe acute respiratory syndrome (SARS) coronavirus probably began through bat-human contact. </p>
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Read more:
<a href="https://theconversation.com/why-bats-dont-get-get-sick-from-the-deadly-diseases-they-carry-55012">Why bats don't get get sick from the deadly diseases they carry</a>
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<p>Expanding settlement towards wilderness areas provides more opportunities for viruses to meet people. Domesticated livestock may carry viruses that infect humans, and the growing human population dictates increasing and more compact livestock production. </p>
<p>Influenza virus infects pigs, cattle and poultry as well as humans. The <a href="https://www.cdc.gov/flu/avianflu/h7n9-virus.htm">H7N9 strain</a> that has infected more than 1,500 people in China and resulted in the death of one-third since 2013, first moved to humans from diseased poultry.</p>
<p>When it comes to numbers though, the most <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(12)61151-9/abstract">important viral transporter</a> is the mosquito. The bite of certain Aedes mosquitoes, for instance, is the primary route for infection with dengue, <a href="https://theconversation.com/explainer-where-did-zika-virus-come-from-and-why-is-it-a-problem-in-brazil-53425">Zika</a> and chikungunya viruses. Queensland is home to these mosquitoes, so outbreaks of dengue <a href="https://www.health.qld.gov.au/__data/assets/pdf_file/0022/444433/dengue-mgt-plan.pdf">occur annually</a>, usually due to an infected traveller arriving from an endemic region. </p>
<p>Research conducted in the Amazon has linked expansion of the mosquito range in endemic areas to <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(12)61151-9/abstract">deforestation and low re-vegetation</a>. Resistance to the relatively few available insecticides may also contribute to their population growth.</p>
<h2>Why viruses are sneaky</h2>
<p>The basic biology of viruses contributes to their capacity to cause disease. Most human viruses replicate almost instantaneously and in huge numbers. As a result, mutations arise at a high rate in the genetic code of a virus. This allows the virus to adapt quickly to an adverse environment, such as the human immune system or drugs. It may also allow a virus to jump from an animal host to humans.</p>
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Read more:
<a href="https://theconversation.com/new-mosquito-threats-shift-risks-from-our-swamps-to-our-suburbs-56350">New mosquito threats shift risks from our swamps to our suburbs</a>
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<p>Some viruses establish a chronic infection, which extends the potential for transmission. After acute illness, Ebola virus hides for many months in parts of the body that generate weak inflammatory responses, such as the <a href="http://www.who.int/reproductivehealth/topics/rtis/ebola-virus-semen/en/">sexual organs</a>, the <a href="https://www.ncbi.nlm.nih.gov/pubmed/28721309">brain and/or the eye</a>.</p>
<p>And although human immunodeficiency virus (HIV) may cause an acute illness, there is usually a long delay between infection and the onset of any disease. Consequently infected people may pass on HIV for years before being aware that they carry the virus.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/225271/original/file-20180628-112604-1nqaooe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/225271/original/file-20180628-112604-1nqaooe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/225271/original/file-20180628-112604-1nqaooe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/225271/original/file-20180628-112604-1nqaooe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/225271/original/file-20180628-112604-1nqaooe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/225271/original/file-20180628-112604-1nqaooe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/225271/original/file-20180628-112604-1nqaooe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/225271/original/file-20180628-112604-1nqaooe.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">Mosquitoes are responsible for the most viral transmissions.</span>
<span class="attribution"><span class="source">from shutterstock.com</span></span>
</figcaption>
</figure>
<p>There are no specific drugs for most dangerous human viruses. This is in part because viruses are a fast growing and diverse group, with no common drug targets to exploit, as has been possible with antibiotics for bacteria. </p>
<p>But another challenge relates to the viral life cycle, which uses the infected person’s cell machinery. Drugs that target the growth of viruses therefore have effects on the person’s cell, which may result in drug side effects. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/hiv-latency-a-high-stakes-game-of-hide-and-seek-49665">HIV latency: a high-stakes game of hide and seek</a>
</strong>
</em>
</p>
<hr>
<p>Also, the capacity of a virus to adapt implies the potential to develop resistance to a drug. Drug treatment for HIV infection involves a <a href="https://aidsinfo.nih.gov/understanding-hiv-aids/fact-sheets/21/56/drug-resistance#">combination of drugs</a> with different actions to address this problem.</p>
<p>Despite the many challenges associated with dangerous viruses, research continues to yield even more innovative solutions. The <a href="https://www.worldmosquitoprogram.org/">World Mosquito Program</a>, run out of Monash University, is one example. This program is based on the discovery that a safe and natural bacteria, <em>Wolbachia</em>, stops viral growth in the mosquito. Insects in regions endemic with mosquito-borne diseases are being infected with <em>Wolbachia</em> to break the transmission cycle. </p>
<p>Ultimately, the cunning strategies used by dangerous viruses are no match for the wide breadth of human ingenuity.</p><img src="https://counter.theconversation.com/content/94747/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Justine R. Smith receives funding from the National Health & Medical Research Council (NHMRC), the Australian Research Council (ARC) and the Rebecca L. Cooper Medical Research Foundation. She is a Science & Technology Australia Superstar of STEM.</span></em></p><p class="fine-print"><em><span>Jill Carr receives funding from the National Health and Medical Research Council (NHMRC). </span></em></p>It doesn’t just seem like the world is experiencing more viral infections than before – it’s a reality. And the way humans live today helps viruses thrive.Justine R. Smith, Professor of Eye & Vision Health, Flinders UniversityJill Carr, Associate Professor, Flinders UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/950762018-04-17T19:43:47Z2018-04-17T19:43:47ZEmerging infectious diseases in India: the scourge that could boost urban development<p>Human societies have seen a significant decrease in mortality from infectious diseases over the past century. However, we must still struggle with ongoing pathologies we once thought were under control (cholera, tuberculosis, plague, etc.) as well as the new ones that have emerged over the last 30 years (HIV/AIDS, Ebola, dengue, <a href="http://www.who.int/mediacentre/factsheets/fs354/en/">West Nile virus</a>, H1N1, etc.). The vast scale of the global epidemics provoked by these viruses forces us to look more closely at the territories where they emerge.</p>
<p>In India, there has been an accelerated spread of dengue and chikungunya, both transmitted by the Aedes mosquito, which is particularly well adapted to urbanised areas. For example, the annual number of new dengue cases is estimated at <a href="https://www.nature.com/articles/nature12060">more than 30 million</a>, while the number of chikungunya cases is believed to have increased by <a href="http://www.nvbdcp.gov.in/chik-cd.html">390% over the last three years</a>. Recent estimates indicate that India is the country with the highest prevalence of these two diseases.</p>
<h2>Cities, and disease, on the rise</h2>
<p>The rise of these infectious diseases is often described in terms of biological processes, but they cannot be reduced to just this dimension. A range of factors play a role, in particular <a href="https://www.springer.com/gp/book/9788132236146">increasing urbanisation and human mobility</a>. The trains connecting Mumbai to its periphery move more than 7 million travellers a day, and New Delhi’s metro system caters to 2.5 million daily commuters.</p>
<p>The growing attention paid to the epidemiology of these viruses can hence be clearly seen as a direct result of the urban transition taking place in India over the last 30 years.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Ty-cnbsV7sg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Daily life for millions of Mumbai’s inhabitants.</span></figcaption>
</figure>
<p>Collaborative studies conducted by the CNRS, the Institut Pasteur and the National Institute of Malaria Research show that nearly <a href="https://www.ncbi.nlm.nih.gov/pubmed/26433076">40% of the population of New Delhi</a> have been infected by the dengue virus at least once in their lifetime. In addition, we were able to highlight an epidemiology of the virus. Because all parts of the city are now hyper-connected, emerging diseases such as dengue affect both privileged and <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0146539">more deprived areas</a>, be they in the centre or peripheral or rural zones.</p>
<p>The social and spatial ubiquity of the disease demands a reevaluation of the geographical models that we use to understand public health problems, as no one knows how, or even where, to counter these diseases that affect not just countries such as India, but the entire planet.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/209875/original/file-20180312-30969-1v7gdg5.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/209875/original/file-20180312-30969-1v7gdg5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/209875/original/file-20180312-30969-1v7gdg5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=204&fit=crop&dpr=1 600w, https://images.theconversation.com/files/209875/original/file-20180312-30969-1v7gdg5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=204&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/209875/original/file-20180312-30969-1v7gdg5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=204&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/209875/original/file-20180312-30969-1v7gdg5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=257&fit=crop&dpr=1 754w, https://images.theconversation.com/files/209875/original/file-20180312-30969-1v7gdg5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=257&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/209875/original/file-20180312-30969-1v7gdg5.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=257&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Density of dengue cases recorded in New Delhi in 2008, 2009 and 2010 (Telle et al., 2016).</span>
<span class="attribution"><span class="source">Olivier Telle</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>While urban development is the matrix for emerging infectious diseases, one also expects these territories to be resilient to these new viruses, with better communication, sanitation and health care, among other attributes. But they do not seem to have been able to adapt: not only do the pathogens continue to spread, but they also emerge and spread more quickly.</p>
<h2>How to tackle an invisible disease</h2>
<p>The problem of managing these diseases arises along with the practices that have led to this lack of resilience. What we mainly find is an inequality in disease management, particularly in large cities and the zones between them.</p>
<p>In New Delhi, more than <a href="https://www.credihealth.com/hospitals/delhi-ncr/malaria">35 hospitals</a> record the number of patients suffering from dengue or chikungunya. Based on the data compiled, New Delhi is officially the most affected city in India due to higher numbers of hospitals that register the diseases. Because of the careful record-keeping, the numbers are seven times higher than in Mumbai or Chennai, which – officially at least – are little affected.</p>
<p>New Delhi’s monitoring network functions most efficiently at the city’s core, and thus infectious diseases are far better managed there than in peripheral municipalities, which are nonetheless an integral part of the metropolitan fabric. Despite the fact that 40% of the urban population lives in towns with fewer than 100,000 inhabitants, small- and medium-size towns are excluded from this monitoring system.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/209900/original/file-20180312-30958-oxqjuw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/209900/original/file-20180312-30958-oxqjuw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/209900/original/file-20180312-30958-oxqjuw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/209900/original/file-20180312-30958-oxqjuw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/209900/original/file-20180312-30958-oxqjuw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=423&fit=crop&dpr=1 754w, https://images.theconversation.com/files/209900/original/file-20180312-30958-oxqjuw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=423&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/209900/original/file-20180312-30958-oxqjuw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=423&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Dr. Santanu Sen, CDC Global, interviewing inhabitants of Jharkhand in 2013 The population of this region, in central eastern India, is mainly tribal and malaria epidemics are frequent there.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/cdcglobal/17192148880/in/photolist-5ZvdHG-4RLiBD-7AqPWo-kh6DAs-scdfU1-dZiUm-hAx6De-hAvAn2-hAvLC3-6fV1VZ-JyvgDZ-hAx658-WZMfH5-6fV1W2-5nWbdr-hAvKvo-hAx7Uv-4eVCHg-dTpdYP-eQZL1L">Santanu Sen</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Territories and infectious diseases are thus caught in a sort of <a href="http://journals.openedition.org/confins/90#tocto2n8">“local globalisation”</a> that requires us to question the concepts of borders, mobility and a spread of the specific urban model.</p>
<p>This process works against an effective management of epidemics: the more widespread diseases become, the more fragmented their management, and the greater their dependence on national, regional and urban health policies.</p>
<h2>Adaptability and a reduction of inequalities</h2>
<p>At present, the question of the management of infectious diseases is relatively absent in health/urban studies, all the more so when they are approached from a municipal perspective.</p>
<p>While local municipalities are at the forefront of efforts to contain the spread of infectious diseases, they are largely ignored by scientists and international organisations when it comes to adopting effective solutions.</p>
<p>While the emergence of these new diseases is the result of complex phenomena – including the rise in local and international mobility, accelerating climate change and the emergence of new viruses – the resilience of the territories lies precisely in their ability to maintain a measure of spatial and social equity.</p>
<p>Indeed, dispersed management efforts inexorably lead to these viruses spreading locally, regionally and internationally, even in what should be less-vulnerable spaces. The main challenge for India, and all the countries that face these risks, is thus to make the diseases that are currently invisible more visible where they exist. At the international level, the only way to do this is through sustainable cooperation.</p>
<h2>Innovating with the cities</h2>
<p>The other challenge is scientific. After having studied all the factors that affect the disease – from a pluridisciplinary perspective, necessarily – methods to contain them need to be developed that take into account the complexity of the cities. In particular, it is impossible to act everywhere in megalopolises.</p>
<p>In India, an emerging project associating virologists, entomologists, geographers and political scientists, supported by the CNRS, the Centre for Policy Research and NIMR proposes a twofold action plan.</p>
<ul>
<li><p>First, suggest and develop innovative methods to control mosquitoes that can be implemented by municipalities.</p></li>
<li><p>Second, using big data, analyse the mobility patterns of millions of citizens and comparing them with the spread of viruses, and thus identify the spaces that need to be monitored. By closely targeting such systems, they may well have an impact beyond the local level. Nonetheless, containment only seems viable in the short term.</p></li>
</ul>
<p>To control these diseases in a more sustainable manner, the health of the inhabitants has to become a key factor of urban development. This involves reforming the management of diseases, and hence of urban centres, developing more equitable urban infrastructures, and most of all, developing inclusive cities. In short, investments are required. However, if the task is important, new approaches and new programmes – for example, smart cities or sustainable towns – may be a means of better containing these epidemics. </p>
<p>It is essential to ensure that these programmes do not remain concentrated in the most privileged areas, as they will have only a limited impact. These epidemics are a scourge, but also an opportunity: in a context where these infectious diseases do not recognise administrative frontiers, much less social ones, they may finally have a positive impact on urban development and encourage the development of more inclusive cities.</p><img src="https://counter.theconversation.com/content/95076/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Olivier Telle a reçu des financements de l'Agence National de la Recherche, de l'Institut Pasteur et du CNRS (PICS Urb-India) </span></em></p>The spread of infectious diseases such as chikungunya is closely linked to urban mobility, yet small Indian cities could play a crucial role in the resilience process.Olivier Telle, Research scientist at CSH, Centre national de la recherche scientifique (CNRS)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/914202018-04-11T14:14:12Z2018-04-11T14:14:12ZWhy Kenya needs policies to tackle dengue and chikungunya viruses<figure><img src="https://images.theconversation.com/files/214267/original/file-20180411-577-1osrtcj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Kenya is one of several countries across the world experiencing an unprecedented outbreak of the <a href="https://www.cdc.gov/chikungunya/symptoms/index.html">chikungunya</a> and <a href="http://www.who.int/mediacentre/factsheets/fs117/en/">dengue</a> viruses. </p>
<p>Dengue fever and chikungunya are two of several arboviral diseases – which are spread to people when they’re bitten by an infected mosquito or tick. </p>
<p>Globally there’s been an <a href="http://www.who.int/mediacentre/factsheets/fs117/en/">increase in the emergence</a> and recurrence of these diseases. </p>
<p>Outbreaks have been reported in Europe – in <a href="http://www.who.int/csr/don/2012_10_17/en/">Portugal</a> in particular – as well as <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3578748/">South East Asia</a> and the <a href="https://vector.amsa.org.au/2017/10/26/441/">Pacific Island countries</a>. Reports of <a href="https://www.japantimes.co.jp/news/2014/09/29/national/another-type-of-dengue-virus-found-in-japan/#.Ws39sn--nIU">dengue fever in Japan</a> have arisen after a lapse of more than 70 years. </p>
<p>And in Africa, Burkina-Faso has also seen <a href="http://www.who.int/csr/don/6-november-2017-dengue-burkina-faso/en/">recurrent dengue outbreaks</a> in the last two years. In <a href="http://outbreaknewstoday.com/dengue-cases-rise-in-brazil-as-does-dengue-spending-90861/">Brazil</a> more than 1.4 million people were infected with dengue in 2016 and have suffered serious after effects. </p>
<p>Kenya’s caseload has seen more than 100 people infected with chikungunya in Mombasa since January 2018 after another 100 were infected with dengue in the seaside town last year.</p>
<p>These are not the first incidents. In the last five years, there have been several outbreak reports of the same diseases in the North Eastern part of Kenya. According to <a href="http://www.who.int/csr/don/09-august-2016-chikungunya-kenya/en/">World Health Organisation records</a>, the town of Mandera in the north east of the country recorded 1700 positive cases of chikungunya in May 2016.</p>
<p>The challenge with these two viruses are that they have no vaccines or treatment. Controlling the vector is the only way to prevent and control these diseases so that outbreaks don’t get out of control. </p>
<p>But part of the problem is that the Kenyan government has not instituted any policies that could regulate the control of these diseases. The government has done this with malaria by instituting several policies in the <a href="http://ghdx.healthdata.org/organizations/national-malaria-control-program-nmcp-kenya">national malaria control programme </a> that has helped control the spread of the disease.</p>
<p>Unless the government establishes policies to deal with dengue fever and chikungunya, like it did for malaria, it will have challenges managing the spread. </p>
<h2>Malaria vector control</h2>
<p>Policies that prevent the spread of malaria in Kenya have been in place for over a decade. There are two main methods: <a href="https://www.malariaconsortium.org/media-downloads/802/Malaria%20prevention%20through%20insecticide%20treated%20nets">insecticide treated bednets</a> and <a href="https://www.malariaconsortium.org/pages/107.htm">indoor spraying of homes</a>. In parts of the country, these methods have resulted in the disease’s caseload <a href="https://malariajournal.biomedcentral.com/articles/10.1186/s12936-017-2119-y">decreasing by over 70%</a>. </p>
<p>But these measures would do little to contain the vector that spreads dengue and chikungunya. </p>
<p>This is because unlike for the malaria vectors that bite at night and can be controlled by sleeping under bed nets, <a href="https://www.ncbi.nlm.nih.gov/pubmed/5301574"><em>Aedes aegypti</em></a> – the main vector that spreads dengue fever and chikungunya – bites during the day. Sleeping under bed nets would therefore have minimal impact in the control of the diseases. </p>
<p>The spraying of insecticides is not advocated because it targets unintended organisms and has a detrimental effect on the environment. In addition, there is the challenge of insecticide resistance. </p>
<h2>A few suggestions</h2>
<p>There are two approaches that the national and county governments could try: urban planning policies as well as policies that target land use. Some of these could be simple and easy to achieve. </p>
<p><a href="https://www.ncbi.nlm.nih.gov/pubmed/29284522">Recent research</a> on the <em>Aedes aegypti</em> – also known as the black mosquito – has shown that the mosquito prefers breeding in:</p>
<ul>
<li><p>garbage like abandoned car tyres, plastic containers and tins,</p></li>
<li><p>water tanks and pots, and </p></li>
<li><p>shady areas </p></li>
</ul>
<p>Urban planning policies that tackle these three areas could reduce the transmission risks of dengue and chikungunya. </p>
<p>One example is a policy that encourages a cleaner environment and for people to dispose their solid waste properly. This would rid urban centres of garbage lying around that provides artificial man-made habitats for the black mosquito.</p>
<p>Another would be for government to provide enough tap water to residents so that water is not stored in pots and tanks. These should be accompanied by education campaigns which sensitise citizens about the importance of covering, emptying and cleaning their domestic water storage containers weekly.</p>
<p>And a third policy could be improved environmental management. This includes better drainage systems around residential areas, and clearing bushes and shady areas. This would help destroy the breeding sites for these mosquitoes. </p>
<p>In terms of land use, <a href="https://www.ncbi.nlm.nih.gov/pubmed/26711512">novel research</a> suggests that attempts to <a href="https://parasitesandvectors.biomedcentral.com/track/pdf/10.1186/s13071-016-1675-2?site=parasitesandvectors.biomedcentral.com">intensify agricultural production</a> could be linked to a high prevalence of dengue fever and chikungunya. In Kenya this could be caused by plants that have been imported into Kenya bringing in invasive weeds like <a href="https://keys.lucidcentral.org/keys/v3/eafrinet/weeds/key/weeds/Media/Html/Parthenium_hysterophorus_(Parthenium_Weed).htm">parthenium hysterophorous</a>. This weed is the <a href="https://www.ncbi.nlm.nih.gov/pubmed/2441221">preferred source of sugar</a> for mosquitoes. Similarly to the protein mosquitoes get from blood, sugar is important for the biology and ecology of mosquitoes. For male mosquitoes, it’s the main source of energy. </p>
<p>There could be a benefit for government to turn vast areas of agricultural land into conservancies.</p>
<p>It’s clear that with proper policies and planning, dengue and chikungunya can be controlled but the government must take the first steps.</p><img src="https://counter.theconversation.com/content/91420/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Eunice Anyango Owino is a medical entomologist and works for the University of Nairobi. She consults with the International Centre of Insect Physiology and Ecology and has received funding from the International Foundation for Sciences (IFS), the National Commission For Science, Technology & Innovation, Kenya. </span></em></p>Kenya must establish policies to tackle dengue fever and chikungunya, like it did for malaria.Eunice Anyango Owino, Medical Entomologist at the School of Biological Sciences, University of NairobiLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/914192018-02-25T07:34:53Z2018-02-25T07:34:53ZHow we pinned down what attracts mosquitos that carry dengue fever<figure><img src="https://images.theconversation.com/files/206221/original/file-20180213-44639-paf95e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Flickr/AFPMB</span></span></figcaption></figure><p>Kenya has seen a rapid <a href="http://www.who.int/csr/don/09-august-2016-chikungunya-kenya/en/">increase</a> in <a href="https://theconversation.com/delhi-has-been-hit-by-a-chikungunya-epidemic-what-is-this-disease-65592">chikungunya</a> and <a href="https://theconversation.com/explainer-what-is-dengue-fever-8571">dengue viruses</a> outbreaks since 2016. Both are mosquito-borne viral infections that lead to debilitating joint and muscle pain.</p>
<p>The two sister diseases are transmitted by the <a href="https://www.ncbi.nlm.nih.gov/pubmed/5301574">Aedes aegypti</a> – a black mosquito with white spots that only bites during the day. The viruses are <a href="http://www.who.int/mediacentre/factsheets/fs327/en/">spread</a> by the female mosquito when she searches for blood as a source of protein and iron which she needs to <a href="https://www.cabdirect.org/cabdirect/abstract/19900596879">form mosquito eggs</a>. </p>
<p>The outbreaks in Kenya have been in areas normally associated with the diseases, such as the coastal city of Mombasa, as well as new areas such as the North Eastern part of the country. </p>
<p>Compared with the large amount of research that’s been done on the vectors that carry malaria, not many studies have been done on those that spread dengue and chikungunya. The main reason for this is that malaria continues to kill one million people each year while dengue and chikungunya claim less than <a href="http://www.eliminatedengue.com/our-research/dengue-fever">25 000 lives a year</a>.</p>
<p>As a result only a limited number of methods have been developed to manage the Aedes aegypti.</p>
<p>We wanted to understand what attracts the black mosquito to its hosts. To do this, we compared commercially available bait traps that contained bait made from natural body odours to see which were more attractive to mosquitoes in their natural environments. Our <a href="https://www.ncbi.nlm.nih.gov/pubmed/25246030">study</a> found that body odour lured the mosquitoes better. We went further and narrowed the attraction down to <a href="https://parasitesandvectors.biomedcentral.com/articles/10.1186/s13071-015-0866-6">four groups of chemical compounds</a> in body odour. </p>
<p>Our findings provide the first evidence of how chemical compounds found in body odour can be used to develop effective bait traps to control dengue and chikungunya. </p>
<h2>Finding the perfect host</h2>
<p>Studies have shown that the <a href="https://www.ncbi.nlm.nih.gov/pubmed/1983456">lure of carbon dioxide</a> in the human breathe help mosquitoes detect a host. Several additional pieces of research have gone further, showing that mosquitoes are attracted to several different stimuli including physical, visual and olfactory. Physical cues include heat and moisture while visual stimuli include light, colour and form.</p>
<p>One study, for example showed that <a href="https://www.ncbi.nlm.nih.gov/pubmed/2230769">mosquitoes were attracted</a> to objects that had been heated and covered in body odour. In another, researchers established that a <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3162918/">combination</a> of heat, moisture and body odour was even more <a href="https://www.nature.com/scientificamerican/journal/v233/n1/pdf/scientificamerican0775-104.pdf">potent</a>. </p>
<p>And in yet <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4983048/">another study</a>, where light traps were baited with carbon dioxide, researchers were able to establish that one of the three mosquitoes that spread malaria – the anopheles gambiae mosquito – bites their hosts at night.</p>
<h2>All about the smell</h2>
<p>Efforts to understand what attracts the Aedes aegypti mosquitoes has been researched in ernest over the past 12 years. </p>
<p>The challenge with many previous studies is that most were conducted on samples in laboratories and not in the field. We set about conducting our tests in the field. In addition, we wanted to test the entire body odour and not just the breathe. </p>
<p>We did two studies. In the first, we used samples of body odour from used socks and worn t-shirts in bait traps in the field. When we compared them to the commercial versions of the traps, we found that the mosquitoes were more attracted to the body odour traps. </p>
<p>Once we established this, we then analysed the body odour and identified most potent chemical compounds. These were from four major chemical groups: the aldehydes, fatty acids, ketones and alcohols. </p>
<p>Aldehydes and fatty acids dominate human odour profiles. But each person has a unique chemical compound profile, with different ratios of the four groups of compounds. This means that different people offer different levels of attractiveness to a mosquito. </p>
<p>The chemical compound profile also changes at different points of the body of an individual. This makes certain parts of the body more or less attractive to the mosquito. </p>
<p>Our second study took these compounds into baited traps. We found that when the compounds were combined with carbon dioxide, they sharpened the body odours that mosquitoes were able to pick up using their antennae.</p>
<p>Our results suggest that there are additional chemical compound candidates that could be commercialised to attract mosquitoes, particularly Aedes aegypti. </p>
<h2>Trap bait</h2>
<p>Ultimately, our findings could lead to a technology made from compounds that come from human body odours to lure and kill mosquitoes that spread the dengue and chikungunya viruses. </p>
<p>For now our next steps are to identify the other compounds in body odour that could also attract mosquitoes. Once these are identified they will need to be tested to see if they are also capable of being used as super bait for mosquitoes.</p><img src="https://counter.theconversation.com/content/91419/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Eunice Anyango Owino is a medical entomologist and works as a lecturer at the University of Nairobi. Funding for the reported findings was from the Swedish International Development Cooperation Agency, SIDA and the research was based at the Behavioural and Chemical Ecology Unit, icipe. </span></em></p>In the future, traps for mosquito that spread the dengue and chikungunya virus could be made from the carbon dioxide in human breathe as well as body odour.Eunice Anyango Owino, Medical Entomologist at the School of Biological Sciences, University of NairobiLicensed 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>
</figcaption>
</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>
<figure class="align-center zoomable">
<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>
</figcaption>
</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>
<figure class="align-center zoomable">
<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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</figure>
<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/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/651632016-09-20T08:12:45Z2016-09-20T08:12:45ZCommon Australian mosquitoes can’t spread Zika<figure><img src="https://images.theconversation.com/files/137304/original/image-20160911-13367-12e344o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The outbreak of Zika virus in Brazil had Australian travellers on alert but transmission is only possible in tropical Queensland.</span> <span class="attribution"><span class="source">Cameron Webb</span>, <span class="license">Author provided</span></span></figcaption></figure><p><a href="http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0004959">New research</a> from Australian scientists shows common local mosquitoes aren’t able to spread Zika virus. This means Australia is unlikely to see a major outbreak of the disease. But a risk remains in northern Queensland.</p>
<p>Since the World Health Organisation’s declaration of a <a href="http://www.who.int/emergencies/zika-virus/en/">Public Health Emergency of International Concern</a> in February, due to the effects of Zika on pregnant women, authorities have been on high alert.</p>
<p>The concern was not just for travellers heading to regions experiencing outbreaks but for the potential for local mosquitoes to spread the disease when those travellers returned home. </p>
<iframe src="https://datawrapper.dwcdn.net/rpAIj/3/" frameborder="0" allowtransparency="true" allowfullscreen="allowfullscreen" webkitallowfullscreen="webkitallowfullscreen" mozallowfullscreen="mozallowfullscreen" oallowfullscreen="oallowfullscreen" msallowfullscreen="msallowfullscreen" width="100%" height="420"></iframe>
<h2>How do mosquitoes spread viruses?</h2>
<p>Mosquitoes are not like dirty syringes, spreading viruses in droplets of blood from person to person. When a mosquito bites, <a href="https://theconversation.com/are-itchier-insect-bites-more-likely-to-make-us-sick-61422">she injects saliva to assist blood-sucking</a>. Unfortunately, mixed in with that spit can be a virus.</p>
<p>For the saliva to become infected, the mosquito must first bite a person or animal infected with a virus. As the mosquito becomes infected, the virus spreads throughout the body of the mosquito; from the legs to the head. </p>
<p>Inside the head are the mosquito’s salivary glands. When they become infected, they can pass on the virus to the next unsuspecting host. </p>
<p>From acquiring to passing on the virus, the process can take anywhere from a few days to a couple of weeks.</p>
<p>Working out which mosquitoes spread which viruses is critical to developing strategic responses to outbreaks of disease.</p>
<h2>Which mosquitoes currently spread Zika virus?</h2>
<p>Back in Uganda, <a href="http://wwwnc.cdc.gov/eid/article/15/9/09-0442_article">where Zika virus was first discovered</a>, it was spread by African forest-dwelling mosquitoes such as <em>Aedes africanus</em>. </p>
<p>Decades later, when the first substantial outbreak was reported on <a href="http://www.nejm.org/doi/full/10.1056/NEJMoa0805715">Yap Island in the Federated States of Micronesia</a>, it was <em>Aedes hensilii</em>.</p>
<p>The relationship between mosquitoes and Zika virus hasn’t been well studied but there is general consensus that, internationally, the mosquito of greatest concern is likely <em>Aedes aegypti</em>. </p>
<p><em>Aedes aegypti</em> is the cockroach of the mosquito world. It loves water-filled containers around the home and it spreads yellow fever, dengue and chikungunya among others. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/137319/original/image-20160912-3763-sq1es2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/137319/original/image-20160912-3763-sq1es2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/137319/original/image-20160912-3763-sq1es2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/137319/original/image-20160912-3763-sq1es2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/137319/original/image-20160912-3763-sq1es2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/137319/original/image-20160912-3763-sq1es2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/137319/original/image-20160912-3763-sq1es2.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">The <em>Aedes aegypti</em> loves to bite.</span>
<span class="attribution"><span class="source">Stephen Doggett</span></span>
</figcaption>
</figure>
<p>It <a href="http://jme.oxfordjournals.org/content/38/3/411.abstract">loves biting people</a> – <a href="http://jme.oxfordjournals.org/content/30/1/94?ijkey=8fb3f2ab4cf539f1e3bec6808a1a4bab3a63ca7f&keytype2=tf_ipsecsha">lots of people</a>. Wherever <em>Aedes aegypti</em> is found, outbreaks of disease keep popping up.</p>
<p>Of the <a href="http://www.publish.csiro.au/pid/6391.htm">300 or so mosquitoes found in Australia</a>, only <em>Aedes aegypti</em> <a href="http://www.sciencedirect.com/science/article/pii/S1286457910000109">can spread exotic viruses</a> and it was considered the most likely to possibly spread Zika virus locally.</p>
<h2>Testing Aussie mozzies</h2>
<p>Australian mosquitoes have been tested against a range of exotic viruses including <a href="http://jme.oxfordjournals.org/content/36/4/508.abstract">dengue</a>, <a href="http://online.liebertpub.com/doi/abs/10.1089/vbz.2009.0106">chikungunya</a>, <a href="http://online.liebertpub.com/doi/abs/10.1089/vbz.2008.0037">West Nile</a>, <a href="http://jme.oxfordjournals.org/content/35/2/132.abstract">Rift Valley fever</a>, <a href="http://jme.oxfordjournals.org/content/40/1/82.abstract">Japanese encephalitis</a> and <a href="http://www.ajtmh.org/content/85/3/446.short">yellow fever</a> viruses.</p>
<p>But no-one had tested the ability of local mosquitoes to spread Zika virus – until now. </p>
<p>Scientists from Queensland Health, the University of Queensland and James Cook University studied the potential for Australian mosquitoes to spread Zika virus and found <em>Aedes aegypti</em> does indeed pose the greatest risk. The results are published today in the journal <a href="http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0004959">PLoS Neglected Tropical Diseases</a>.</p>
<p>The study tested seven types of mosquito implicated in the spread of disease in Australia, including <em>Aedes notoscriptus</em>, <em>Aedes vigilax</em>, <em>Culex annulirostris</em>, <em>Culex quinquefasciatus</em> and <em>Aedes aegypti</em>. These mosquitoes are frequent biters, are found close to local suburbs and have been shown to transmit other pathogens. </p>
<p>The researchers exposed groups of mosquitoes in the laboratory to blood infected with one of two strains of Zika virus: one originating from a traveller returning to Australia from the Pacific; another derived from the original strain isolated in Uganda.</p>
<p>Once the mosquitoes fed on the blood and virus mixture, they were tested to see if they become infected with the virus and, most importantly, whether the virus was being transmitted in their spit.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/138413/original/image-20160920-11103-10dnymd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/138413/original/image-20160920-11103-10dnymd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/138413/original/image-20160920-11103-10dnymd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/138413/original/image-20160920-11103-10dnymd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/138413/original/image-20160920-11103-10dnymd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/138413/original/image-20160920-11103-10dnymd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/138413/original/image-20160920-11103-10dnymd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Mosquito-control efforts should remain focused on <em>Aedes aegypti</em>.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-436043980/stock-photo-girl-with-blond-hair-sitting-with-his-back-turned-and-scratching-bitten-red-swollen-neck-skin-from-mosquito-bites-in-the-summer-in-the-forest-close-up-up-of-visible-insect-bites-irri.html?src=ugB6hK17vaGv0tjJn7RqDA-1-51">dimid_86/Shuterstock</a></span>
</figcaption>
</figure>
<p>The only mosquito found to transmit Zika virus was, unsurprisingly, <em>Aedes aegypti</em>. </p>
<p>However, what was surprising was the relatively low rate of transmission. Fourteen days after taking a Zika virus-infected blood meal, only 67% of infected mosquitoes were found with virus in their saliva. Based on other mosquito-borne viruses, such as <a href="http://jvi.asm.org/content/88/11/6294.short">chikungunya</a>, it would be expected to be much higher. The result, however, echoes the results of <a href="http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0004543">another study from the United States</a>.</p>
<p><em>Aedes aegypti</em> is playing an important role in outbreaks of Zika virus but perhaps it is due to more than just their ability to transmit the virus. They have a propensity to bite humans, and to bite many different people. </p>
<p>Mosquito-control efforts <a href="http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0004993">should therefore remain focused</a> on <em>Aedes aegypti</em>.</p>
<h2>Is Australia safe from Zika?</h2>
<p>These results have important implications for predicting where in Australia we may see an outbreak of Zika virus.</p>
<p><em>Aedes aegypti</em> is generally only found in <a href="https://www.mja.com.au/journal/2009/190/5/dengue-and-climate-change-australia-predictions-future-should-incorporate?inline=true">tropical regions of Queensland</a>. The mosquito isn’t in the major urban area of Southeast Queensland such as Brisbane, Sunshine Coast or Gold Coast. The areas at <a href="https://www.health.qld.gov.au/publications/clinical-practice/guidelines-procedures/diseases-infection/governance/dengue-mgt-plan.pdf">greatest risk</a> are likely to be those around Cairns, Townsville as well as the Torres Strait. There is a moderate risk around Rockhampton and Gladstone. </p>
<p>The absence of <em>Aedes aegypti</em> from any of our major metropolitan regions means the risk of a major outbreak is extremely low. </p>
<p>But there is a risk of a minor disease outbreak where the <em>Aedes aegypti</em> is present. Every year, there are small local outbreaks of dengue in tropical Queensland; there’s a chance we’ll see similar outbreaks of Zika.</p>
<p>The good news is that authorities in tropical Queensland are well-equipped to deal with outbreaks of mosquito-borne disease. They have been <a href="https://www.health.qld.gov.au/publications/clinical-practice/guidelines-procedures/diseases-infection/governance/dengue-mgt-plan.pdf">responding to local outbreaks of dengue</a> for decades and are <a href="https://www.health.qld.gov.au/publications/clinical-practice/guidelines-procedures/diseases-infection/governance/chikungunya-management-plan.pdf">prepared for potential outbreaks of chikungunya</a>. The response to the threat of Zika virus remains essentially the same.</p>
<p>The potential for human to human sexual transmission of Zika virus remains a small but not insignificant risk for all regions of Australia. As <a href="http://apps.who.int/iris/bitstream/10665/204421/1/WHO_ZIKV_MOC_16.1_eng.pdf">international health authorities recommend</a>, travellers returning from countries experiencing outbreaks of Zika virus must use condoms or abstain from sex for six months. </p>
<p>If you’re planning to travel to a Zika-affected area, consult the <a href="http://smartraveller.gov.au/Pages/default.aspx">Smart Traveller website</a> for the most up-to-date information about the best ways to avoid mosquito bites.</p><img src="https://counter.theconversation.com/content/65163/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>Andrew Francis van den Hurk works for Queensland Health, which funded the research. </span></em></p>New research shows common local mosquitoes aren’t able to spread Zika. This means Australia is unlikely to see a major outbreak of the disease. But a risk remains in northern Queensland.Cameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/655922016-09-19T14:45:09Z2016-09-19T14:45:09ZDelhi has been hit by a chikungunya epidemic – what is this disease?<figure><img src="https://images.theconversation.com/files/138244/original/image-20160919-11120-hvpobq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Newborn aedes albopictus mosquito.</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-396424921/stock-photo-close-up-newborn-aedes-albopictus-mosquito-pest-animal-contagion.html?src=6x_puCu1_IKkg6hiHyp79A-1-10">Smith1972/Shutterstock.com</a></span></figcaption></figure><p>Chikungunya is not a name that rolls easily off the tongue. It is a Swahili word meaning “that which bends up”. It describes the symptoms of this crippling arthritic disease, a disease which is <a href="http://www.bbc.co.uk/news/world-asia-india-37370582">currently gripping Delhi</a> in India.</p>
<p><a href="http://www.who.int/mediacentre/factsheets/fs327/en/">Chikungunya</a> is a viral disease that is transmitted by mosquitoes. People who are unlucky enough to contract the disease tend to suffer from a fever and severe joint pain, causing them to have a painful and contorted posture. Other symptoms include headaches, nausea, fatigue, rash, swollen joints and muscle pain. These are similar symptoms to those infected with dengue virus which, although historically attributed to higher mortality rates, is said to be less painful and shorter lived than chikungunya infections. </p>
<p>Symptoms usually begin around three to seven days following a bite from an infected mosquito. As with other mosquito-borne viruses, chikungunya is classed as an <a href="https://theconversation.com/why-are-emerging-viruses-here-and-why-now-29311">emerging or re-emerging pathogen</a> in many countries. Epidemics occur in cycles which can have many intervening years. However, the past couple of decades have seen an increase in the number of large <a href="http://www.who.int/mediacentre/factsheets/fs327/en/">outbreaks</a>.</p>
<p>The <a href="https://www.arcgis.com/home/item.html?id=ec0fa39273364d5eb53f628dacc82056">widening geographical scope</a> of the virus is due to the expanding range of the mosquitoes that carry it. Increasing global temperatures, international travel and population densities all contribute to allowing mosquitoes to take up residence in previously unoccupied areas. </p>
<h2>Avoiding mosquitoes is the best defence</h2>
<p>There is no cure for chikunguya infections, so medical treatment involves relieving symptoms. Most sufferers are expected to make a full recovery, although this may take up to a year or more. There is also no vaccine for preventing infections either, so the best defence is to avoid mosquito bites. </p>
<p>Unlike the mosquitoes that transmit malaria, which are active at night, chikungunya is <a href="http://www.oxitec.com/five-facts-need-know-aedes-aegypti/">spread by species</a> that feed during the day – which makes bite prevention more challenging. This requires measures in addition to sleeping under mosquito nets. For instance wearing long-sleeve clothing, and the use of mosquito repellents and deterrents. The virus persists in the blood for five to seven days so it is also important to prevent mosquitoes feeding on an infected person during this time to reduce the risk of human to mosquito transmission.</p>
<p>Virus carrying mosquitoes are found across tropical and subtropical regions. They have adapted well to living in <a href="http://ecdc.europa.eu/en/healthtopics/vectors/mosquitoes/pages/aedes-aegypti.aspx">populated areas</a> and can breed in small pools of stagnant water. Small amounts of water in <a href="http://www.dengue.gov.sg/subject.asp?id=100">discarded tyres, flowerpots and food containers</a> can be used by female mosquitoes to lay batches of around 200 eggs. Preventing access to these water sources is essential for reducing disease transmission through population control. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/138249/original/image-20160919-11117-1osuuvq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/138249/original/image-20160919-11117-1osuuvq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/138249/original/image-20160919-11117-1osuuvq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/138249/original/image-20160919-11117-1osuuvq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/138249/original/image-20160919-11117-1osuuvq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/138249/original/image-20160919-11117-1osuuvq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/138249/original/image-20160919-11117-1osuuvq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Mosquitoes breed in small pools of stagnant water.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-146952131/stock-photo-a-discarded-old-tyre-in-a-puddle-of-contaminated-water.html?src=MMx8RPEBfZPwCfDvWAEXQg-1-10">Steve Buckley/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>Chikunguya, dengue and Zika viruses are spread by the same mosquito species and exist in the same areas. Due to the similarity of the symptoms of all three infections, many historical epidemics that were <a href="https://www.biomedcentral.com/about/press-centre/science-press-releases/03-03-2016">reported as dengue virus</a> could have been caused by chikunguya. Similarly, the number of Zika infections early in the current epidemic could have been <a href="https://www.romper.com/p/can-zika-be-misdiagnosed-the-virus-shares-similar-markers-with-dengue-fever-10172">under reported</a> and attributed to dengue or chikungunya viruses. </p>
<p>Originally recorded in Tanzania in 1952, minor outbreaks of chikungunya virus were documented in Asia from the<a href="http://www.searo.who.int/entity/emerging_diseases/topics/Chikungunya/en/"> early 1960s</a>. The first major epidemic <a href="http://www.who.int/csr/don/09-august-2016-chikungunya-kenya/en/">was in 2004</a> on the coast of Kenya after which <a href="http://www.who.int/denguecontrol/arbo-viral/other_arboviral_chikungunya/en/">the virus spread</a> to many islands of the Indian Ocean, India and South-East Asia. Recently other Asian, European and North American countries have recorded imported cases. A few of these countries have developed virus transmission in local mosquito populations.</p>
<p>The continuation of human, viral and environmental factors which promote the emergence and spread of chikungunya and other mosquito-borne diseases suggest that the <a href="https://publichealthmatters.blog.gov.uk/2016/01/08/mosquito-borne-diseases-in-the-21st-century/">pattern of outbreaks</a> is likely to continue for some time. As the virus spreads, population immunity will eventually reduce the frequency and range of these outbreaks since humans develop <a href="http://www.paho.org/hq/index.php?option=com_content&view=article&id=9724%3A2014-chikungunya-un-nuevo-virus-en-la-region-de-las-americas&catid=1443%3Aweb-bulletins&Itemid=135&lang=en">lifelong immunity</a> following infection. Isolated populations, such as some Pacific and Caribbean islands, are able to successfully reduce the rate of infection after a couple of transmission cycles. But in areas of large population densities, such as Delhi, this may take significantly longer.</p><img src="https://counter.theconversation.com/content/65592/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Claire Donald receives funding from the Medical Research Council of the UK. </span></em></p>A virologist gives the low-down on chikungunya.Claire Donald, Post-doctoral Research Assistant, University of GlasgowLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/618612016-08-03T05:38:22Z2016-08-03T05:38:22ZZika, or dengue and Chikungunya: what should you be worried about at the Rio Olympics?<figure><img src="https://images.theconversation.com/files/132906/original/image-20160803-12234-z2i7mp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">_Aedes aegypti_: bringing you Zika, dengue and Chikungunya. </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/jacobs_ian/9549802367/">Ian Jacobs/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>A number of <a href="http://www.telegraph.co.uk/sport/0/rio-olympics-which-athletes-have-withdrawn-over-zika-fears/">athletes have pulled out</a> of the Rio 2016 Olympics due to concerns about the Zika virus and the widening list of birth defects associated with infections during pregnancy. But <a href="http://www.reuters.com/article/us-olympics-zika-brazil-minister-idUSKCN0YT0QM">Brazilian authorities have said</a> there’ll be “close to zero” cases of Zika recorded during the Olympic Games. </p>
<p>Last year’s dengue outbreak in Brazil certainly supports the idea that mosquito-borne infections dwindle in the cooler winter months, but they hardly “returned to zero”. Dengue reached 35,000 probable cases in the state of Rio by the end of May 2015, then dropped to 1,600 new cases per fortnight throughout August.</p>
<p>Zika had already reached 46,000 probable cases by the end of May 2016 and is transmitted by the same <em>Aedes aegypti</em> mosquito as dengue. Should we then expect to have at least 1,600 cases in Rio during the Olympic Games? </p>
<h2>Good and bad news</h2>
<p>This is hard to predict but it’s still possible to approximate. The good news is that Rio de Janeiro’s disease surveillance authorities have detected a decrease in Zika virus infections in the city. </p>
<p>This is due in part – like the fall in dengue cases – to winter season, when mosquitoes are less active. But it’s also because the number of susceptible individuals has decreased, as many people have already had the disease. </p>
<p>The bad news is that the <em>Aedes aegypti</em> mosquito is very urbanised and prefers to stay indoors rather than outdoors. So transmission can continue during the winter months.</p>
<p>The official number of Zika cases is also a significant underestimation of the true number of infections. A <a href="http://www.ncbi.nlm.nih.gov/pubmed/26403318">study in French Polynesia</a>, where the virus was emerging in 2013 before it moved to Brazil during a canoeing competition in August 2014, suggested that <a href="http://www.nejm.org/doi/full/10.1056/NEJMoa0805715#t=article">80% of Zika cases are asymptomatic</a> and so go undetected. </p>
<h2>Insidious nature</h2>
<p>Factoring in the expected number of asymptomatic infections is crucial, since the birth defects associated with Zika infections in pregnancy have been identified even in pregnancies <a href="http://www.nejm.org/doi/full/10.1056/NEJMoa1604037#t=article">where Zika symptoms were not apparent</a>.</p>
<p>The projected numbers above also don’t account for potential sexual transmission of Zika. The virus has been shown to lurk in the <a href="http://www.ncbi.nlm.nih.gov/pubmed/27088817">sperm of infected men</a> for up to 60 days, and this contribution to Zika transmission rates is not well understood. Female-to-male sexual transmission has also <a href="http://www.cdc.gov/mmwr/volumes/65/wr/mm6528e2.htm">been identified</a> recently. </p>
<p>Several studies have indicated that the disease disproportionately affects women, with <a href="http://biorxiv.org/content/early/2016/05/26/055459">at least 60% more reported</a> infections compared to men. In this regard, the insidious nature of the virus is scary: men may inadvertently infect a pregnant partner without even realising they’re carrying the disease.</p>
<h2>And the numbers</h2>
<p>After the influx of the expected 500,000 athletes and spectators to Rio, an estimated 64 detected mosquito transmissions, 256 asymptomatic infections and 96 sexually infected women can be expected from the projection above. That would mean 416 Zika infections in Rio travellers (0.0832%). </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/132907/original/image-20160803-12230-1jh1r0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/132907/original/image-20160803-12230-1jh1r0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/132907/original/image-20160803-12230-1jh1r0a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/132907/original/image-20160803-12230-1jh1r0a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/132907/original/image-20160803-12230-1jh1r0a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/132907/original/image-20160803-12230-1jh1r0a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/132907/original/image-20160803-12230-1jh1r0a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Not-so-cute babies.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/iaea_imagebank/25277276699/in/photolist-pEfttE-E3PjtE-oHp58p-oHp2YW-hFbZoE-ngndLa-nEJrfL-Gbke76-DbNk78-GhR9Yi-nAppjT-ne5WzM-nGHuH4-nxzkqY-FtrjJT-5JPq2r-Fkoksm-FkyJ2D-EPpm2y-zeHNxv-DGYeey-yXcTGt-DKhGPp-DGYfro-ETEhpQ-yX7P2q-CMTRsk-ETEhpu-DiaXvy-EvEDHv-zeHNdH-yX6WBj-rJLsnZ-uGy4Mr-rGTVSK-uGMWuD-tKxcZE-upYo5s-tKxcBf-upY6rs-AbcuLo-vFz3FA-vrp112-vHSHT6-uM1P36-uLSiyU-vHhWsj-vFz2NU-vroWSZ-v7FC84">IAEA Imagebank</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>These numbers are <a href="http://www.ncbi.nlm.nih.gov/pubmed/27040593">higher than previous estimates</a> of about one traveller infected, which was modelled on <em>Aedes aegypti</em> biting rates from a 2008 dengue epidemic, and which didn’t consider the 2013 Rio dengue data. </p>
<p>Similarly, the chief medical officer of the 2016 Rio Olympics, João Grangeiro, <a href="https://www.rio2016.com/en/news/why-the-rio-2016-olympic-games-will-be-completely-safe-for-athletes-participants-and-spectators-zika">reported no infections</a> in the 17,000 people already involved in preliminary games test events.</p>
<p>This is somewhat surprising and is perhaps a testament to the excellent resources applied to protecting the participants thorough mosquito control measures. It optimistically suggests Zika transmission may be largely occurring in areas outside where most travellers will be staying. </p>
<h2>Two large elephants</h2>
<p>But the elephant(s) in the room are the dengue and Chikungunya viruses – both of which are also endemic to Rio at the moment. These diseases immediately make travellers much more ill than the mild fever and rash experienced during Zika infection. </p>
<p>Dengue sends people to bed with a raging fever and Chikungunya produces a cripplingly painful arthritis. Dengue has been rampaging through Rio with a ferocity greater than the Zika virus, reaching 63,000 probable cases by the end of May, as well as seven deaths. </p>
<p>Using the same projections, 88 cases of dengue might be expected in Rio travellers, as well as six cases of Chikungunya. In total, the 500,000 Rio visitors might end up having up to 510 combined infections of dengue, Zika or Chikungunya (0.103%). </p>
<p>These numbers aren’t exactly “close to zero”. Travellers should follow their countries’ advisories in taking precautions. Importantly, men and women planning families in the next six months should not travel to affected regions. </p>
<h2>The biggest threat</h2>
<p>Those not planning a family should not let arboviruses forestall their visit when infections are completely preventable, even without a vaccine on offer. But don’t forget to get your yellow fever and influenza vaccines before you go. </p>
<p>As per the <a href="http://www.who.int/csr/disease/zika/information-for-travelers/en/">World Health Organisation’s advice</a>, travellers should wear light-coloured long clothing, since mosquitoes are attracted to dark colours. They should also wear mosquito repellent on their skin and clothing. This is particularly important as the <em>Aedes aegypti</em> mosquito tends to approach from behind and bite the ankles, meaning many will not even be aware they’ve been bitten. </p>
<p>Repellents should contain WHO-approved ingredients such as DEET (diethyltoluamide) or IR 3535 or Icaridin. Sleeping places should be inspected and mosquitoes removed – or nets used if this is not possible. </p>
<p>The biggest threat to travellers’ health is actually complacency. It’s hard to be over-anxious in a crowd of people who seemingly don’t care, and the social science behind convincing people to protect themselves is perhaps the biggest hurdle yet to preventing infections.</p><img src="https://counter.theconversation.com/content/61861/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Joanne Macdonald recently started the spin-out company BioCifer Pty. Ltd. to assist in commercialising diagnostics technology. She is a shareholder of the company.</span></em></p><p class="fine-print"><em><span>Davis Fernandes Ferrera receives funding from FAPERJ and CNPq (Brazil). </span></em></p>Zika had already reached 46,000 probable cases by the end of May 2016 and is transmitted by the same mosquito species as dengue and Chikungunya.Joanne Macdonald, Senior Lecturer, Molecular Engineering, University of the Sunshine CoastDavis Fernandes Ferreira, Professor of Microbiology, Universidade Federal do Rio de Janeiro (UFRJ)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/612492016-06-21T16:02:52Z2016-06-21T16:02:52ZMosquito bite research: could slapping on some cream help stop Zika?<figure><img src="https://images.theconversation.com/files/127192/original/image-20160619-11112-mgyi26.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There's something in the bite.</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&autocomplete_id=&searchterm=mosquito%20bite&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=278964704"> chakkrachai nicharat/Shutterstock.com</a></span></figcaption></figure><p>It’s well known that viruses are spread by mosquito bites. The details of how these pathogens initially take hold in their human host has not been clear, until now. Researchers at the universities of Leeds and Glasgow have <a href="http://bit.ly/28LAltb">discovered</a> that it’s the body’s inflammatory response that actually helps viruses invade and multiply. And preventing this inflammatory response may just halt the virus in its tracks. </p>
<p>With the rapid spread of <a href="http://www.who.int/mediacentre/factsheets/zika/en/">Zika</a> in the Americas, attention has been drawn to this group of neglected mosquito-borne <a href="http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0000247">viral</a> <a href="http://www.who.int/neglected_diseases/diseases/en/">infections</a>. The Zika virus is not alone in causing problems, others such as <a href="http://www.who.int/topics/dengue/en/">dengue</a> and <a href="http://www.who.int/mediacentre/factsheets/fs327/en/">chikungunya</a> viruses are infecting millions of people each year. Yet there’s little doctors can do to help people who get sick. </p>
<p>In the new research, published in the journal Immunity, we used mice to study the bites of the <em>Aedes aegypti</em> mosquito. This is one of the most dangerous species of mosquito. It spreads infections such as Zika, dengue and chikungunya. When a mosquito bites you it triggers an immune response, in which immune cells called neutrophils and macrophages rush to the site. These immune cells are normally responsible for defending the body against infection and repairing the damage done by biting insects. But instead of helping, some of these cells get infected and unintentionally replicate the virus, our research found.</p>
<p>The macrophage cells inadvertently became infected at bites and start producing lots of new virus. More replication means more virus, which then allows it to spread round the body. This was surprising as this family of viruses are not known for infecting macrophage cells. However, when we prevented these cells from moving into mosquito bite sites, the bite did not enhance the infection anymore. So it looks as though some of the body’s own immune defence cells are unwittingly the key to the virus’s success. </p>
<h2>A silver bullet?</h2>
<p>Despite the enormous disease burden of mosquito-borne viral infections – they are responsible for hundreds of millions of cases across the world – there are few specific medicines or vaccines to prevent or treat these diseases. To makes things worse, climate change and globalisation are helping these mosquitoes spread to new parts of world.</p>
<p>We now want to look at whether medications such as anti-inflammatory creams can suppress bite inflammation. We predict this might stop the virus establishing an infection if used quickly enough after a bite appears. <em>Aedes</em> mosquitoes only bite during the day, so a bite is something people would notice. </p>
<p>We’re now hoping that this research could be the first step in using commonly available anti-inflammatory drugs to treat bite inflammation before any symptoms set in. It might be possible that a single cream could act as an effective way to stop these viruses before they can spread round the body to cause disease. What’s particularly exciting about this approach is that it could work against a multitude of other mosquito transmitted viruses. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/127198/original/image-20160619-11110-iq5dgb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/127198/original/image-20160619-11110-iq5dgb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=367&fit=crop&dpr=1 600w, https://images.theconversation.com/files/127198/original/image-20160619-11110-iq5dgb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=367&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/127198/original/image-20160619-11110-iq5dgb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=367&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/127198/original/image-20160619-11110-iq5dgb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=461&fit=crop&dpr=1 754w, https://images.theconversation.com/files/127198/original/image-20160619-11110-iq5dgb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=461&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/127198/original/image-20160619-11110-iq5dgb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=461&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Putting anti-inflammatory cream on the bite might stop the virus spreading.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/s/mosquitoe+bite/search.html?page=2&thumb_size=mosaic&inline=436509421">dimid_86/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>Nobody anticipated the Zika outbreak and, before that, nobody anticipated chikungunya. This means it’s hard for governments and drug companies to justify the costs associated with developing medicines. Medicines take years to develop and cost vast amounts of money. Most of these infections occur in poor parts of world, so it’s unlikely these medicines will be made for each virus “just in case”. There are estimated to be hundreds of other mosquito-borne viruses out there and it’s hard to predict what’s going to start the next outbreak. But bite inflammation is a common aspect of all these infections, so targeting it makes sense.</p>
<p>It’s best not to get bitten in the first place, but for those who do get bitten, future research will hopefully show that slapping on an anti-inflammatory cream could stop you getting sick.</p><img src="https://counter.theconversation.com/content/61249/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Clive McKimmie receives funding from the Medical Research Council and the Wellcome Trust. </span></em></p><p class="fine-print"><em><span>Marieke Pingen 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>Inflammation caused by mosquito bites helps viruses to infect the body.Clive McKimmie, University academic fellow, University of LeedsMarieke Pingen, Postdoctoral research fellow, University of LeedsLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/606462016-06-19T14:55:13Z2016-06-19T14:55:13ZChikungunya epidemic casts its pall: what you should know<figure><img src="https://images.theconversation.com/files/125522/original/image-20160607-15021-1fv0im2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A patient with symptoms of the Chikungunya virus in a Dominican hospital. Outbreaks have been reported in Africa, Asia, Europe, and the Indian and Pacific Oceans</span> <span class="attribution"><span class="source">Reuters/Ricardo Rojas </span></span></figcaption></figure><p><em>Parts of Northern Kenya have been struck by an epidemic of chikungunya, a mosquito borne viral infection. Half of the population <a href="http://www.ipsnews.net/2016/06/stepping-up-the-fight-to-end-cholera-and-chikungunya-outbreaks-in-mandera-county-kenya/">in one Kenyan county</a> which borders Ethiopia and Somalia has come down with the infection. There’s real risk of travellers spreading it to new areas. Professor Collins Ouma from the <a href="https://www.afidep.org/">African Institute for Development Policy</a> in Nairobi answers some important questions about the outbreak.</em></p>
<p><strong>What is chikungunya? What are its common symptoms?</strong></p>
<p>Chikungunya virus is transmitted to humans through mosquito bites. The most common symptoms of the chikungunya virus infection are fever and joint pain. Other symptoms include headaches, muscle pain, joint swelling or a rash. In addition, other people develop sudden fever, chills, nausea and vomiting. </p>
<p>In Kiswahili, “chikungunya” means “that which contorts or bends up”. This refers to the contorted or stooped posture of patients who are afflicted with the severe joint pain (arthritis). This is one of the disease’s most common features.</p>
<p>Symptoms usually show between three and seven days after someone is bitten by an infected mosquito. There is no vaccine to prevent or medicine to treat the chikungunya virus infection. The only available method of prevention is through shielding from mosquito bites. Travellers visiting countries where there are cases of chikungunya virus should use insect repellent, wear long sleeves and pants and stay in places with air conditioning or that use window and door screens. </p>
<p><strong>Where is it likely to occur and why?</strong></p>
<p>There have been documented outbreaks in Africa, Asia, Europe, and the Indian and Pacific Oceans. There is an anticipated risk that the virus will be imported to new areas by infected travellers. By 2013, local transmission had been identified in 45 countries or territories throughout the Americas with more than 1.7 million suspected cases reported to the <a href="http://www.who.int/denguecontrol/arbo-viral/other_arboviral_chikungunya/en/">Pan American Health Organisation</a> from affected areas.</p>
<p>The mosquito vectors associated with large outbreaks of chikungunya are <a href="http://www.cdc.gov/dengue/resources/30jan2012/comparisondenguevectors.pdf">Aedes aegypti</a>, which is also associated with yellow fever, and <a href="http://www.cdc.gov/dengue/resources/30jan2012/comparisondenguevectors.pdf">Aedes albopictus</a>. Both are associated with dengue fever as well. Aedes aegypti is confined to the tropics and sub-tropics while the Aedes albopictus mainly live in temperate and even in colder regions. In recent times, Aedes albopictus has spread from Asia to areas in Africa, Europe and the Americas.</p>
<p>Typical of mosquito vectors, the Aedes albopictus thrives in a wider range of water-filled breeding sites than Aedes aegypti. This explains the abundance of Aedes albopictus in rural, peri-urban and shady areas. Aedes aegypti is more closely associated with human habitation and uses indoor breeding sites as well as the same artificial outdoor habitats as Aedes albopictus.</p>
<p>In Africa, several other mosquito vectors have also been implicated in disease transmission. There is also accumulating evidence that some animals such as non-primates, rodents, birds and small mammals may act as reservoirs to the <a href="http://www.who.int/mediacentre/factsheets/fs327/en/">disease</a>. </p>
<p><strong>What similarities or differences are there when compared to its now better known cousin <a href="https://theconversation.com/africa/topics/zika-virus">Zika</a>?</strong></p>
<p>Similar to chikungunya, the Zika virus is also primarily transmitted by biting Aedes aegypti female mosquitoes. It also has no preventive vaccines or medications and the only available treatment is supportive care of symptoms.</p>
<p><strong>What is the global response to chikungunya?</strong></p>
<p>The current responses to chikungunya are outlined by the <a href="http://www.who.int/mediacentre/factsheets/fs327/en/">World Health Organisation</a>. The response has several focus areas. These include:</p>
<ul>
<li><p>formulating evidence-based outbreak management plans, </p></li>
<li><p>providing technical support and guidance to manage cases and outbreaks in countries effectively, </p></li>
<li><p>supporting countries to improve their reporting systems, </p></li>
<li><p>providing training on clinical management, diagnosis and vector control at the local and regional level, and </p></li>
<li><p>publishing guidelines and handbooks on case management and vector control for World Health Organisation member states. </p></li>
</ul>
<p>There has been a heightened urgency to encourage affected countries to develop and maintain the capacity to detect and confirm cases, manage patients and implement social communication strategies to reduce the presence of the mosquito vectors. </p>
<p>Integrated vector control has mainly been through methods to reduce the source by eliminating all potential vector breeding places near the domestic or peri-domestic areas. Authorities have used larvicides to eliminate larvae and biological control. This is by, for instance, introducing fish that feed on the larvae in water tanks and other water sources.</p>
<p><strong>Has Kenya been able to meet these guidelines and deal with the epidemic?</strong> </p>
<p>The Kenyan government has responded quickly to prevent the spread of chikungunya. One of its approaches has been to strengthen health systems, especially those associated with a well-functioning surveillance. This ensures responses to disease outbreaks are versatile and resilient. </p>
<p>The government has also emphasised building the capacity of health staff, using community-driven prevention measures. These prepare the local systems for quick response before external support is mobilised. In addition, there are also enhanced public-private partnerships and cross-border collaborations to curb the spread of the virus before it becomes an epidemic. </p>
<p>The government has realised that to effectively control the virus, health institutions must be adequately equipped. They need to detect early signs of unusual disease patterns, track and investigate cases, and must be able to diagnose and confirm outbreaks promptly. </p>
<p>These approaches present an all-inclusive paradigm in health systems development that not only combat chikungunya but also other infectious diseases in Kenya and beyond.</p><img src="https://counter.theconversation.com/content/60646/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Collins Ouma 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>There is no vaccine to prevent or medicine to treat the chikungunya virus infection. The only available method of prevention is through shielding people from mosquito bites.Collins Ouma, Head of Research and Knowledge Translation at the African Institute for Development Policy and Professor, Maseno UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/577892016-04-29T10:04:45Z2016-04-29T10:04:45ZTo fight Zika, let’s genetically modify mosquitoes – the old-fashioned way<p>The near <a href="http://www.who.int/emergencies/zika-virus/en/">panic caused by the rapid spread</a> of the <a href="http://www.who.int/mediacentre/factsheets/zika/en/">Zika virus</a> has brought new urgency to the question of how best to control mosquitoes that transmit human diseases. <em>Aedes aegypti</em> mosquitoes bite people across the globe, spreading three viral diseases: <a href="http://www.cdc.gov/dengue/">dengue</a>, <a href="http://www.cdc.gov/chikungunya/">chikungunya</a> and <a href="http://www.cdc.gov/zika/">Zika</a>. There are no proven effective vaccines or specific medications to treat patients after contracting these viruses.</p>
<p><a href="http://www.nytimes.com/aponline/2016/04/19/world/americas/ap-lt-zika-war-on-mosquito.html">Mosquito control</a> is the only way, at present, to limit them. But that’s no easy task. Classical methods of control such as insecticides are <a href="http://doi.org/10.3390/insects7010002">falling out of favor</a> – they can have adverse environmental effects as well as <a href="http://doi.org/10.1371/journal.ppat.1001000">increase insecticide resistance</a> in remaining mosquito populations. New <a href="http://www.thelancet.com/journals/langlo/article/PIIS2214-109X(16)00048-6/abstract">mosquito control methods are needed</a> – now.</p>
<p>The time is ripe, therefore, to explore a long-held dream of <a href="https://www.sciencedaily.com/terms/vector_(biology).htm">vector biologists</a>, including me: to use genetics to stop or limit the spread of mosquito-borne diseases. While gene editing technologies have advanced dramatically in the last few decades, it is my belief that we’ve overlooked older, tried and true methods that could work just as well on these insects. We can accomplish the goal of producing mosquitoes incapable of transmitting human pathogens using the same kinds of selective breeding techniques people have been using for centuries on other animals and plants.</p>
<h2>Techniques on the table</h2>
<p>One classic strategy for reducing insect populations has been to <a href="http://doi.org/10.1007/1-4020-4051-2">flood populations with sterile males</a> – usually produced using irradiation. When females in the target population mate with these males, they produce no viable offspring – hopefully crashing population numbers.</p>
<p>The modern twist on this method has been to generate transgenic males that carry a dominant lethal gene that essentially makes them sterile; offspring sired by these males die late in the larval stage, eliminating future generations. This method has been promulgated by the <a href="http://www.oxitec.com/ridl-science/">biotech company Oxitec</a> and is currently <a href="http://dx.doi.org/10.1371/journal.pntd.0003864">used in Brazil</a>.</p>
<p>Rather than just killing mosquitoes, a more effective and lasting strategy would be to genetically change them so they can no longer transmit a disease-causing microbe.</p>
<p>The powerful new CRISPR gene editing technique could be used to make transgenes (genetic material from another species) take over a wild population. This method <a href="http://dx.doi.org/10.1016/j.celrep.2015.03.009">works well in mosquitoes</a> and is potentially a way to <a href="http://doi.org/10.1534/genetics.115.177592">“drive” transgenes into populations</a>. CRISPR could help quickly spread a gene that confers resistance to transmission of a virus – what scientists call refractoriness.</p>
<p>But CRISPR has been controversial, especially as applied to human beings, because the transgenes it inserts into an individual can be passed on to its offspring. No doubt using CRISPR to create and release genetically modified mosquitoes into nature would stir up controversy. The U.S. Director of National Intelligence, James Clapper, has gone so far as to <a href="https://www.technologyreview.com/s/600774/top-us-intelligence-official-calls-gene-editing-a-wmd-threat/">dub CRISPR a potential weapon of mass destruction</a>.</p>
<p>But are transgenic technologies necessary to genetically modify mosquito populations?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/119663/original/image-20160421-27019-1jtncvf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/119663/original/image-20160421-27019-1jtncvf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/119663/original/image-20160421-27019-1jtncvf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/119663/original/image-20160421-27019-1jtncvf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/119663/original/image-20160421-27019-1jtncvf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/119663/original/image-20160421-27019-1jtncvf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/119663/original/image-20160421-27019-1jtncvf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/119663/original/image-20160421-27019-1jtncvf.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">Examples of successful artificial selection of various traits through the years. In the center is a cartoon of the ‘block’ scientists would like to select for in mosquitoes so they can’t pass on the virus.</span>
<span class="attribution"><span class="source">Jeff Powell</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Selective breeding the old-fashioned way</h2>
<p>Genetic modification of populations has been going on for centuries with great success. This has occurred for almost all commercially useful plants and animals that people use for food or other products, including cotton and wool. Selective breeding can produce immense changes in populations based on naturally occurring variation within the species.</p>
<p>Artificial selection using this natural variation has proven effective over and over again, especially in the agricultural world. By choosing parents with desirable traits (chickens with increased egg production, sheep with softer wool) for several consecutive generations, a “true breeding” strain can be produced that will always have the desired traits. These may look very different from the ancestor – think of all the breeds of dogs derived from an ancestor wolf.</p>
<p>To date, only limited work of this sort has been <a href="http://www.ncbi.nlm.nih.gov/pubmed/3834805">done on mosquitoes</a>. But it does show that it’s possible to select for mosquitoes with reduced ability to transmit human pathogens. So rather than introducing transgenes from other species, why not use the genetic variation naturally present in mosquito populations?</p>
<p>Deriving strains of mosquitoes through artificial selection has several advantages over transgenic approaches.</p>
<ul>
<li>All the controversy and potential risks surrounding transgenic organisms (GMOs) are avoided. We’re only talking about increasing the prevalence in the population of the naturally occurring mosquito genes we like.</li>
<li>Selected mosquitoes derived directly from the target population would likely be more competitive when released back to their corner of the wild. Because the new refractory strain that can’t transmit the virus carries only genes from the target population, it would be specifically adapted to the local environment. Laboratory manipulations to produce transgenic mosquitoes are known to <a href="http://doi.org/10.1073/pnas.0305511101">lower their fitness</a>.</li>
<li>By starting with the local mosquito population, scientists could select specifically for refractoriness to the virus strain infecting people at the moment in that locality. For example, there are four different “varieties” of the dengue virus called serotypes. To control the disease, the selected mosquitoes would need to be refractory to the serotype active in that place at that time.</li>
<li>It may be possible to select for strains of mosquitoes that are unable to transmit multiple viruses. Because the same <em>Aedes aegypti</em> mosquito species transmits dengue, chikungunya and Zika, people living in places that have this mosquito are simultaneously at risk for all three diseases. While it has not yet been demonstrated, there is no reason to think that careful, well-designed selective breeding couldn’t develop mosquitoes unable to spread all medically relevant viruses.</li>
</ul>
<p>Fortunately, <em>Ae. aegypti</em> is the easiest mosquito to rear in captivity and has a generation time of about 2.5 weeks. So unlike classical plant and animal breeders dealing with organisms with generations in years, 10 generations of selection of this mosquito would take only months.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/119469/original/image-20160420-25634-1e0x116.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/119469/original/image-20160420-25634-1e0x116.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/119469/original/image-20160420-25634-1e0x116.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/119469/original/image-20160420-25634-1e0x116.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/119469/original/image-20160420-25634-1e0x116.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/119469/original/image-20160420-25634-1e0x116.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/119469/original/image-20160420-25634-1e0x116.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/119469/original/image-20160420-25634-1e0x116.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 are working out mass rearing techniques for Aedes mosquitoes – their generation time is only 2.5 weeks.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/iaea_imagebank/25015286483">IAEA Imagebank</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>This is not to imply there may not be obstacles in using this approach. Perhaps the most important is that the genes that make it hard for these insects to transmit disease may also make individual insects weaker or less healthy than the target natural population. Eventually the lab-bred mosquitoes and their offspring could be out-competed and fade from the wild population. We might need to continuously release refractory mosquitoes – that is, the ones that aren’t good at transmitting the disease in question – to overcome selection against the desirable refractory genes.</p>
<p>And mosquito-borne pathogens themselves evolve. Viruses may mutate to evade any genetically modified mosquito’s block. Any plan to genetically modify mosquito populations needs to have contingency plans in place for when viruses or other pathogens evolve. New strains of mosquitoes can be quickly selected to combat the new version of the virus – no costly transgenic techniques necessary.</p>
<p>Today, plant and animal breeders are increasingly using new gene manipulation techniques to further improve economically important species. But this is only after traditional artificial selection has been taken about as far as it can to improve breeds. Many mosquito biologists are proposing to go directly to the newest fancy transgenic methodologies that have never been shown to actually work in natural populations of mosquitoes. They are skipping over a proven, cheaper and less controversial approach that should at least be given a shot.</p><img src="https://counter.theconversation.com/content/57789/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jeff Powell receives funding from the US National Institutes of Health </span></em></p>Look beyond transgenic techniques that add new genes to a species. People have used selective breeding techniques to change plants and animals for millennia – why not try them on mosquitoes?Jeffrey Powell, Professor, Yale UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/540052016-02-02T14:06:28Z2016-02-02T14:06:28ZWhy don’t we wipe mosquitoes off the face of the Earth?<figure><img src="https://images.theconversation.com/files/109955/original/image-20160202-32251-1pdmam9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> </figcaption></figure><p>A blood-sucking, disease-spreading, whining creature is always going to be a hard sell, even to nature lovers. And the dreaded mosquito is now the prime suspect behind the sudden <a href="https://theconversation.com/uk/topics/zika">arrival and explosive spread of Zika virus</a> in Central and South America. Zika is transmitted by a mosquito vector <em><a href="http://www.bbc.co.uk/news/health-35427491">Aedes aegypti</a></em>, a pan-global tropical species already well known for spreading diseases such as yellow and dengue fever. </p>
<p>There are only around <a href="http://mosquito-taxonomic-inventory.info/valid-species-list">3,500 species of mosquito</a>, which is modest for a family of insects – but their impact on human health and welfare is catastrophic. Female <em>Anopheles</em> mosquitoes carry the parasite that causes <a href="http://www.who.int/mediacentre/factsheets/fs094/en/">up to 500m cases of malaria a year</a> while the Asian Tiger Mosquito, <em><a href="http://www.cdc.gov/dengue/resources/30Jan2012/albopictusfactsheet.pdf">Ades albopictus</a></em>, spreads dengue fever and the <a href="http://www.cdc.gov/chikungunya/">chikugunya</a> virus. Mosquitoes have been ready vectors for emergent diseases such as <a href="http://www.cdc.gov/westnile/">West Nile virus</a> and now Zika. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/109960/original/image-20160202-32227-1w07nnz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/109960/original/image-20160202-32227-1w07nnz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/109960/original/image-20160202-32227-1w07nnz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=391&fit=crop&dpr=1 600w, https://images.theconversation.com/files/109960/original/image-20160202-32227-1w07nnz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=391&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/109960/original/image-20160202-32227-1w07nnz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=391&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/109960/original/image-20160202-32227-1w07nnz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=492&fit=crop&dpr=1 754w, https://images.theconversation.com/files/109960/original/image-20160202-32227-1w07nnz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=492&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/109960/original/image-20160202-32227-1w07nnz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=492&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 Aedes aegypti mosquito spreads the Zika virus.</span>
<span class="attribution"><span class="source">mrfiza</span></span>
</figcaption>
</figure>
<p>Mosquitoes are credited with causing more misery and loss to humanity than any other organism (with the obvious exception of ourselves). Mosquitoes are unlovely creatures, all twitchy legged and whining, their larvae infesting miasmas and dismal swamps. And <a href="http://www.independent.co.uk/environment/climate-change/climate-change-could-see-deadly-tropical-diseases-spread-to-the-uk-10126458.html">under the right conditions</a> they are mobile and expansionist pioneers, perfectly at home in the disrupted habitats we create.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/109965/original/image-20160202-32251-1jwq54s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/109965/original/image-20160202-32251-1jwq54s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/109965/original/image-20160202-32251-1jwq54s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/109965/original/image-20160202-32251-1jwq54s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/109965/original/image-20160202-32251-1jwq54s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/109965/original/image-20160202-32251-1jwq54s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/109965/original/image-20160202-32251-1jwq54s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/109965/original/image-20160202-32251-1jwq54s.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">Aedes albopictus: spreads dengue fever and chikugunya.</span>
<span class="attribution"><span class="source">Centers for Disease Control and Prevention</span></span>
</figcaption>
</figure>
<p>Which begs the question: what good do they do – and if we could wipe them from the face of the Earth should we?</p>
<p>As pointed out by ecologist Sarah Fang, the consensus is that mosquitoes <a href="http://www.nature.com/news/2010/100721/full/466432a.html">do not do any unique or particular good</a> that would be missed. If you judge them according to ecologist Charles Elton’s gentle but evocative idea of <a href="http://www.lancaster.ac.uk/users/philosophy/awaymave/onlineresources/animal%20community.pdf">each creature having a niche</a> – much as every English village has a cast of characters who have their place such as butcher, baker and policeman – then mosquitoes seem to have no special purpose on the face of it. So one wouldn’t miss them, surely?</p>
<h2>Mozzie lovers could argue…</h2>
<p>Arguments in favour of mosquitoes fall into two broad categories. First that their sheer numbers are an essential link in some food webs, notably the Arctic tundras where, for a few brief weeks in summer they hatch in extraordinary numbers, creating visible clouds of adults and a <a href="http://www.mosquitoreviews.com/mosquitoes-purpose.html">very rich food supply to migratory birds</a> that have come north to exploit this bounty. </p>
<p>Fang also suggests that the mosquitoes’ assaults may be ferocious enough to divert the migration lines of caribou with possible consequences at a landscape scale as the herds’ grazing and trampling shift location. In an unusually exact link between mosquitoes and their predators, a study of foraging Little Forest Bats, <em><a href="http://bie.ala.org.au/species/Vespadelus+vulturnus">Vespadelus vultuernus</a></em>, in eastern Australia revealed a very heavy reliance on adults of the mosquito <a href="http://medent.usyd.edu.au/arbovirus/mosquit/aedesvigilax.htm"><em>Aedes vigilax</em></a>. So, that <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0064081">Little Forest Bats need mossies</a> may be as good a case as mosquitoes can muster.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/109963/original/image-20160202-32237-u442zr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/109963/original/image-20160202-32237-u442zr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/109963/original/image-20160202-32237-u442zr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/109963/original/image-20160202-32237-u442zr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/109963/original/image-20160202-32237-u442zr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/109963/original/image-20160202-32237-u442zr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/109963/original/image-20160202-32237-u442zr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/109963/original/image-20160202-32237-u442zr.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"></a>
<figcaption>
<span class="caption">Little Forest Bat: about the only thing that would miss mosquitoes.</span>
<span class="attribution"><span class="source">Doug Beckers</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Juvenile mosquitoes are also important in some freshwater foodwebs, including as prey to specialists such as the mosquito fish, <em><a href="http://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=846">Gambusia affinis</a></em> or in the tiny pools of water held in the leaf bases of pitcher plants and bromeliads high in the rainforest canopy. In among the canopy trees a miniature fauna of vividly coloured poison dart frogs and crabs thrive in the bromeliad pools, called <a href="http://entnemdept.ufl.edu/frank/bromeliadbiota/bromfit.htm">phytotelmata</a>, feeding off the bodies of drowned juvenile mosquitoes. But despite poison dart frogs and bats having their own fan club among ecologists and nature enthusiasts, they are unlikely to sway the majority of people in favour of mosquitoes.</p>
<p>The second argument is that mosquitoes have a more general role providing ecosystem services such as pollination by adults or driving the release of nutrients as their young feed on organic detritus. But although <a href="http://www.mosquitoreviews.com/mosquitoes-niche-pollinate.html">mosquitoes can act as pollinators</a> for orchids and golden rods, among other plants, they don’t have a monopoly – they are not especially suited to this role and there are plenty of other pollinators to take their place. </p>
<p>While the <a href="http://www.globalresearch.ca/death-and-extinction-of-the-bees/5375684">decline of the honey bee</a> is a prominent example of an ecosystem service at peril, mosquitoes are just another one of the many pollination bit-part players, an unloved understudy that can be written out of the part. Their significance has always been to menace. </p>
<h2>… but then again</h2>
<p>As the Portuguese explorer João de Barras <a href="https://books.google.co.uk/books?id=5KKNCgAAQBAJ&pg=PA139&lpg=PA139&dq=tropics+God+has+placed+a+striking+angel+with+a+flaming+sword+of+deadly+fevers&source=bl&ots=pPcEY6EmB2&sig=r55TaRH3Jj1y1bZNIXtZiRQGwLk&hl=en&sa=X&ved=0ahUKEwjg36iF19jKAhUBXRQKHaaVBrAQ6AEIKDAD#v=onepage&q=tropics%20God%20has%20placed%20a%20striking%20angel%20with%20a%20flaming%20sword%20of%20deadly%20fevers&f=false">said of the tropics</a>:</p>
<blockquote>
<p>God has placed a striking angel with a flaming sword of deadly fevers, who prevents us from penetrating into the interior to the springs of this garden.</p>
</blockquote>
<p>So there seems no great reason to defend mosquitoes. Their destruction would lift a terrible curse from humanity. Except for one nagging doubt …</p>
<p>All that warm, nutritious blood suddenly available. There are plenty of other midges and mites, black flies and fleas out there just waiting for the opportunity to step in. Be careful what you wish for.</p><img src="https://counter.theconversation.com/content/54005/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mike Jeffries 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>They spread disease and misery and account for millions of deaths every year. There’s not a lot to be said for mosquitoes.Mike Jeffries, Teaching Fellow, Ecology, Northumbria University, NewcastleLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/538712016-02-02T01:12:48Z2016-02-02T01:12:48ZHere’s why we don’t have a vaccine for Zika (and other mosquito-borne viruses)<p>As Zika fear rises, especially in the wake of the World Health Organization last night <a href="http://www.who.int/mediacentre/news/statements/2016/emergency-committee-zika-microcephaly/en/">declaring</a> a state of public health emergency, people are inevitably asking why we don’t have a vaccine to protect against the mosquito-borne virus. </p>
<p>Zika is generally a mild illness, causing fever, rash and joint pain, which usually resolves within seven to ten days. It was originally restricted to small outbreaks in the Pacific islands, Southeast Asia and Africa. </p>
<p>Due to the previously low impact of the virus and the <a href="http://www.ghtcoalition.org/files/VAC_vacc_invst_fs.pdf">estimated</a> US$160-500 million it costs to develop a vaccine, Zika vaccine has not been on the radar. Other severe and potentially fatal mosquito-borne diseases such as malaria, dengue, and West Nile virus <a href="http://www.who.int/campaigns/world-health-day/2014/vector-borne-diseases/en/">affect millions of people</a> each year and have been a higher priority. </p>
<p>That has all changed with the recent “<a href="http://www.nytimes.com/2016/01/29/health/zika-virus-spreading-explosively-in-americas-who-says.html">explosive</a>” spread of Zika in the Americas and the potential link with microcephaly (reduced head size and brain damage) in babies of pregnant women who were infected. </p>
<p>Now we’re playing catch up on the research needed to develop vaccines. We know very little about how Zika replicates, how it causes disease, or how the immune system protects against infection. </p>
<p>So what is the status of Zika vaccine development? And how does this compare with the other mosquito-borne viruses that continue to have such a devastating impact on the world’s health? </p>
<h2>Vaccine development</h2>
<p>The ideal vaccine induces a strong response from the immune system, gives long-term protection with few doses, and causes no side effects. Though quickly developing such a vaccine is rarely this simple. </p>
<p><strong>Zika</strong> </p>
<p>It’s early days, but scientists from the Public Health Agency of Canada, the Butantan Institute in Brazil, and the US National Institutes of Health have <a href="http://america.aljazeera.com/articles/2016/1/25/zika-virus-set-to-spread-across-americas-spurring-vaccine-hunt.html">started work</a> on Zika vaccines. These research teams may have vaccine candidates ready for initial clinical trials towards the end of the year. </p>
<p>Although full regulatory approval of a successful vaccine would take many years, it could potentially be used in public health emergencies within a year. </p>
<p><strong>Yellow fever</strong></p>
<p>The yellow fever vaccine, developed in 1938, has been highly successful at protecting against the virus, which <a href="http://www.health.gov.au/yellowfever">can cause</a> bleeding, jaundice, kidney and liver failure and, ultimately, death. Of the 44 countries at risk of yellow fever in Africa and the Americas, <a href="http://www.who.int/mediacentre/factsheets/fs378/en/">35 have incorporated</a> Yellow Fever vaccines into infant immunisation programs. </p>
<p>It is a live vaccine, in which a “weakened” virus induces a protective immune response against subsequent infection. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/109907/original/image-20160202-32231-tys66x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/109907/original/image-20160202-32231-tys66x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/109907/original/image-20160202-32231-tys66x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/109907/original/image-20160202-32231-tys66x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/109907/original/image-20160202-32231-tys66x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/109907/original/image-20160202-32231-tys66x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/109907/original/image-20160202-32231-tys66x.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">The Yellow Fever vaccine successfully protects against the virus, but is .</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/unamid-photo/8189656969/">UNAMID/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Live vaccines generally give strong protection, but safety is a significant issue, particularly in people with a weakened immune system. </p>
<p><strong>Dengue</strong> </p>
<p>Dengue fever is a widespread tropical disease caused by dengue virus, which is transmitted by mosquitoes. Late-stage clinical trials of dengue vaccines are underway, and a vaccine has <a href="http://www.denguevaccines.org/sanofi-pasteur-releases-phase-3-trial-results-dengue-vaccine-candidate-asia">recently been licensed</a> for use, but so far only in Mexico. </p>
<p>The field is littered with promising but failed vaccines that could not provide protection against the major strains of dengue virus. Nonetheless, there is hope that one will be available more widely in the coming years. </p>
<p><strong>Chikungunya</strong></p>
<p>Chikungunya virus has <a href="http://cid.oxfordjournals.org/content/47/4/469.full">recently emerged</a> as a serious human pathogen, causing fever and excruciating pain in the joints that can last months. </p>
<p>As with Zika, chikungunya was long considered unimportant because of its limited geographic distribution. Its dramatic expansion over the past decade, particularly in Southeast Asia and the Americas, has led to mobilisation of the vast medical research capabilities of the United States in response to the threat of it becoming established there. </p>
<p>Chikungunya vaccine development is proceeding rapidly, with a number of vaccines entering clinical trials. Researchers have <a href="https://www.niaid.nih.gov/news/newsreleases/2015/Pages/ChikungunyaVaxTrial.aspx">reported early successes</a>, but we are at least several years away from getting an approved vaccine.</p>
<p><strong>Malaria</strong></p>
<p>The big one is malaria, which <a href="http://www.who.int/features/factfiles/malaria/en/">kills more than</a> 400,000 people a year. Scientists have been working on malaria vaccines for decades. </p>
<p>The <a href="http://www.who.int/malaria/news/2015/background-brief-malaria-vaccine/en/">RTS,S vaccine</a>, developed by Glaxo Smith Kline, was successful in clinical trials and may soon be routinely used.</p>
<p>However, it <a href="http://www.who.int/malaria/news/2015/background-brief-malaria-vaccine/en/">only worked</a> for some patient groups and provided only partial protection. Given its partial efficacy, there is debate in the medical community about the vaccine’s value.</p>
<p>The search continues for better vaccines.</p>
<h2>Why is it so difficult to develop vaccines?</h2>
<p>There is no recipe for the perfect vaccine. Despite the ever-increasing sophistication of vaccine technology, vaccine development often comes down to “suck it and see”. Many vaccines look promising in pre-clinical testing, only to fall over during the slow and expensive clinical trial process.</p>
<p>For many infectious diseases, we still don’t know what type of immune response is the most effective in providing protection. Since vaccines induce a protective immune response against infection, this can make vaccine design very difficult.</p>
<p>Vaccine safety is a major issue. “Live” or “attenuated” vaccines that involve a related or weakened version of the pathogen are often the most effective. But there is still the potential for these vaccines to <a href="http://vaccine-safety-training.org/live-attenuated-vaccines.html">cause disease</a>, especially in recipients with weakened immune systems. </p>
<p>Vaccines go through a long process of clinical trials and assessment by regulators before they are approved for routine human use. This is a necessary process, but it sets a very high bar for approval. One of the most successful vaccines ever produced – the smallpox vaccine – is a live vaccine and would probably not have been approved by today’s regulators due to safety concerns.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/109909/original/image-20160202-32240-bko05l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/109909/original/image-20160202-32240-bko05l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/109909/original/image-20160202-32240-bko05l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/109909/original/image-20160202-32240-bko05l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/109909/original/image-20160202-32240-bko05l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/109909/original/image-20160202-32240-bko05l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/109909/original/image-20160202-32240-bko05l.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">Smallpox was eradicated in 1980.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/pahowho/9522456825/">Pan American Health Organization/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>For dengue, there is an additional complication. People previously infected with dengue are at risk of developing much more severe disease when infected with a second, related dengue strain. Similarly, dengue vaccination could also lead to enhanced disease, rather than protection, when a person subsequently encounters the virus. This additional safety concern has markedly complicated and slowed dengue vaccine development.</p>
<h2>Urgent priority</h2>
<p>Zika causes mild fever in humans that on its own does not make a strong argument for a vaccine. But the possible link to microcephaly in unborn children, even though not yet definitely confirmed, makes vaccine development – and necessary funding – an urgent priority. </p>
<p>It’s also important to fund basic research to provide a necessary springboard for current and future vaccine development programs.</p>
<p>In the meantime, people in affected areas, including travellers, should take care to avoid mosquito bites by wearing long clothing and using repellents, bed nets and window screens.</p><img src="https://counter.theconversation.com/content/53871/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>As Zika fear rises, people are inevitably asking why we don’t have a vaccine to protect against the mosquito-borne virus.Suresh Mahalingam, Principal Research Leader, Institute for Glycomics, Griffith UniversityMichael Rolph, Senior research fellow, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/535572016-01-25T19:16:44Z2016-01-25T19:16:44ZDoes Zika virus pose a threat to Australia?<figure><img src="https://images.theconversation.com/files/109112/original/image-20160125-432-1paaxyn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There is little doubt the virus can make it to Australia.</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-88364941/stock-photo-mosquito-sucking-human-blood-on-extreme-macro.html?src=pp-same_artist-88364992-2&ws=1">mrfiza/Shutterstock</a></span></figcaption></figure><p>They’re small, spindly insects but their threat never dwindles – the bites of mosquitoes threaten death and disease in many parts of the world. The emergence of a little-known virus, Zika, from an African forest, is the latest to alarm the public, politicians and health authorities because of its potential link to birth defects.</p>
<h2>What is Zika virus?</h2>
<p><a href="https://theconversation.com/zika-a-rare-benign-virus-suddenly-turns-nasty-and-heads-for-the-us-52792">Zika virus</a> is a mosquito-borne virus closely related to dengue and Yellow Fever viruses. Discovered almost 70 years ago in a Ugandan forest, the virus generally only causes a mild illness. Symptoms include rash, fever, joint pain and conjunctivitis. </p>
<p>Severe symptoms aren’t common and the illness was never thought to be fatal.</p>
<p>Despite detection throughout <a href="http://www.ncbi.nlm.nih.gov/pubmed/19788800">Africa and Asia</a>, the virus rarely entered the spotlight of scientific research. It was overshadowed by the spread and impact of <a href="http://www.cdc.gov/dengue/">dengue</a> and <a href="http://www.cdc.gov/chikungunya/">chikungunya</a> viruses, which infect millions of people across the regions.</p>
<p>In the last decade, Zika virus outbreaks <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4036769/">have occurred</a> in the <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2819875/">Pacific</a>, with <a href="http://onlinelibrary.wiley.com/doi/10.1111/1469-0691.12707/full">reports of severe illness</a>. But again, Zika was considered a lesser threat than dengue and chikungunya viruses.</p>
<p>Everything changed in 2015 when Zika virus reached the Americas.</p>
<h2>New outbreaks and severe symptoms</h2>
<p>Since the first local Zika virus infection, <a href="http://www.cdc.gov/mmwr/volumes/65/wr/mm6503e1er.htm?s_cid=mm6503e1er.htm_w">cases have been reported</a> from at least 19 countries or territories in the Americas, with more than one million suspected cases.</p>
<p>Rapid spread of an emerging mosquito-borne pathogen is news enough but people are also panicked by reports of more serious consequences of Zika virus infections, including <a href="http://www.nytimes.com/2016/01/22/world/americas/zika-virus-may-be-linked-to-surge-in-rare-syndrome-in-brazil.html?_r=1">post-viral Guillain-Barré Syndrome</a>, an autoimmune condition where there person’s nerves are attacked by their own body. </p>
<p>Of most concern has been the rapid rise in rates of <a href="http://www.cdc.gov/ncbddd/birthdefects/microcephaly.html">microcephaly</a>, a birth defect which causes babies to be born with unusually small heads, in regions where Zika virus has been circulating. </p>
<p>While the role of Zika virus as the cause of microcephaly has not yet been confirmed, there is <a href="http://www.cdc.gov/mmwr/volumes/65/wr/mm6503e2er.htm?s_cid=mm6503e2er.htm_w">growing evidence</a> of a connection between the two where pregnant women have been infected with the virus. </p>
<p>Babies born with microcephaly, and those who died shortly after birth, have tested positive for the virus, and there are close regional associations between clusters of birth defects and Zika virus. </p>
<p>There is enough concern for the Centres for Disease Control to <a href="http://www.cdc.gov/mmwr/volumes/65/wr/mm6502e1.htm">issue health warnings</a> to pregnant women planning to travel to these regions. Some health authorities are even <a href="http://www.abc.net.au/news/2016-01-23/birth-defects-in-latin-america-spark-zika-virus-panic/7109812">advising people</a> to postpone pregnancies.</p>
<p>There is no vaccine for Zika virus. Stopping mosquito bites is the only way to prevent infection.</p>
<h2>Is Australia at risk of a Zika virus outbreak?</h2>
<p>There is little doubt the virus can make it to Australia. There have already been a number of infections reported in travellers arriving in Australia from the <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4055592/">Cook Islands</a> and <a href="http://www.ajtmh.org/content/89/3/516.full">Indonesia</a>. </p>
<p>Mosquito-borne viruses generally aren’t spread from person to person. Only through the bite of an infected mosquito can the virus be transmitted. </p>
<p>In the case of Zika, there have been some unusual cases of transmission, including <a href="http://www.sciencemag.org/news/2011/04/sex-after-field-trip-yields-scientific-first">through sex</a> and the bite of an <a href="http://www.tm.mahidol.ac.th/seameo/2015-46-3/09-642913p460.pdf">infected monkey</a>. Despite these unusual circumstances, mosquitoes will still play the most important role in any local transmission.</p>
<p>While dozens of mosquitoes are capable of spreading local mosquito-borne pathogens, such as <a href="http://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1005070">Ross River virus</a>, only one of the 300 or so mosquitoes found in Australia can transmit Zika virus: <em>Aedes aegypti</em>, the Yellow Fever Mosquito, which is only found in north Queensland.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/109084/original/image-20160124-447-gufx23.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/109084/original/image-20160124-447-gufx23.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/109084/original/image-20160124-447-gufx23.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/109084/original/image-20160124-447-gufx23.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/109084/original/image-20160124-447-gufx23.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/109084/original/image-20160124-447-gufx23.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/109084/original/image-20160124-447-gufx23.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">The Yellow Fever mosquito, Aedes aegypti, is critical to the spread of Zika virus in many regions of the world, including Australia.</span>
</figcaption>
</figure>
<p>For local <em>Aedes aegypti</em> to spread Zika virus, they must bite an infected traveller shortly after they return from a country where the virus is circulating. </p>
<p>While the chances of this happening are small, there is then a risk of a local outbreak occurring as the infected mosquito bites people who’ve never left the country.</p>
<p>This is the process that occurs in <a href="https://theconversation.com/explainer-what-is-dengue-fever-8571">outbreaks of dengue</a> in Far North Queensland. If we can get outbreaks of dengue, there is no reason we cannot, or won’t, get an outbreak of Zika in the future.</p>
<h2>How to reduce the risk of transmission</h2>
<p>Fortunately, authorities are well placed to contain an outbreak of Zika virus, as the required strategies are the same as <a href="https://www.health.qld.gov.au/clinical-practice/guidelines-procedures/diseases-infection/diseases/mosquito-borne/outbreak-procedures/default.asp">management of dengue outbreaks</a>.</p>
<p>Perhaps the real message here for Australian authorities is that they need to work diligently to keep exotic mosquitoes out of the country. </p>
<p>While <em>Aedes aegypti</em> may not become established in southern cities, even with a <a href="https://theconversation.com/is-climate-change-to-blame-for-outbreaks-of-mosquito-borne-disease-39176">changing climate</a>, there is great potential that <em>Aedes albopictus</em>, better known as the Asian Tiger Mosquito, <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0134975">could become established in southern cities</a>. As well as a vector of Zika virus, it can spread dengue and chikungunya viruses and be a significant nuisance-biting pest. Keeping this mosquito out of our cities is critical.</p>
<p>Australians planning travel to South and Central America, including the <a href="http://www.abc.net.au/news/2016-01-25/rio-vows-to-protect-olympics-from-zika-virus/7111228">Rio Olympics</a>, should take precautions to avoid mosquito bites. Irrespective of Zika virus, mosquito-borne dengue and chikungunya viruses have infected millions of people, causing thousands of deaths, in the last few years and are reason alone to pack <a href="https://theconversation.com/chemical-or-natural-whats-the-best-way-to-repel-mozzies-36879">mosquito repellents</a>. Be prepared to cover up with long sleeved shorts and long pants if in regions where risk is high.</p><img src="https://counter.theconversation.com/content/53557/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>They’re small, spindly insects but their threat never dwindles – the bites of mosquitoes threaten death and disease in many parts of the world.Cameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/424022015-08-19T03:22:11Z2015-08-19T03:22:11ZHow a new test is revolutionising what we know about viruses in our midst<figure><img src="https://images.theconversation.com/files/90839/original/image-20150805-22496-1gics2b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Detecting viruses in wild-caught mosquitoes provides intimate detail of disease transmission cycles.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/publichealthuw/19529872674/in/photolist-vKMGJE-wqjd6c-wGNVTe-wHiuUp-wqcmdu-wqc1oN-vKMGwL-wqcm9m-wHivc8-wHiv9T-wqjcz2-wG6Bh5-wqckNb-wqjcx8-wqc1fm-wEuk8S-wqc1dY-vKWg54-wGNVQD-vKMGns-wHiv8v-wGNW5X-2vVkpu-qJWvom-hg5nvz-wqjd3r-vKMGZQ-wqjcsZ-wEuk3G-wG6Bp9-vKWfYx-vKMGAy-wHiuzr-onja7R-onz3iG-8bgE3t-ftJaP5-fuj1Gy-FDNvY-8haqb5-54K4y5-8h7byc-8h7bxi-aZXeqk-fhpwyd-8EVHkB-rFQjYy-8gU4fa-f5ZKB-584D1k">University of Washington SPH/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Mosquitoes’ role in the spread of disease make them perhaps one of the most reviled insects in the world. But it also makes them more studied than most of their brethren. Now, a new technique for collecting mosquito saliva from the field has made monitoring mosquitoes both more sensitive and inexpensive.</p>
<p>Mosquito-borne disease remains an intractable problem both in Australia and globally. The seasonal curse of <a href="http://cmr.asm.org/content/14/4/909.short">Ross River fever</a> is well known to Australians, as is <a href="http://www.biomedcentral.com/content/pdf/1756-3305-7-379.pdf">dengue</a>, which is readily acquired when holidaying in Southeast Asia or even tropical northern Queensland. </p>
<p>Public health warnings and mosquito control remain central to the control of such diseases. But our ability to predict disease outbreaks is hampered by laborious mosquito trapping, underdeveloped forecasting models and unreliable human blood testing. </p>
<h2>Good spit</h2>
<p>Detecting viruses in wild-caught mosquitoes provides intimate detail of disease transmission cycles, helping us understand the complexities of disease ecology and providing new avenues for predicting and controlling outbreaks. Such virus hunting traditionally involved cumbersome mass collections of mosquitoes shipped live to faraway labs where they were ground up and analysed by scientists to search for traces of viruses. </p>
<p>What’s more, all this effort only showed that a mosquito in that “haystack” was carrying the virus; it couldn’t show whether it was capable of infecting someone with that virus. This, of course, is an important distinction since many mosquitoes can pick up a virus but not pass it on.</p>
<p>But an elegant new technology is helping to improve field detection of viruses, reduce cost and identify only mosquitoes capable of infecting someone with the virus. </p>
<p>A few years ago, <a href="http://www.pnas.org/content/107/25/11255.short">Queensland scientists discovered</a> that if trapped mosquitoes could be convinced to spit onto a specially coated card that preserves virus genes (made from DNA and RNA), then the viruses they carry could be more easily detected. </p>
<p>The spat-on cards are processed in a lab where the genes are “amplified” using a process that uses enzymes to probe the cards for virus genes. These genes are then copied, analysed and identified. This is how the concept of the mosquito “spit test” was born.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/90842/original/image-20150805-22488-1ak2s3p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/90842/original/image-20150805-22488-1ak2s3p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/90842/original/image-20150805-22488-1ak2s3p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/90842/original/image-20150805-22488-1ak2s3p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/90842/original/image-20150805-22488-1ak2s3p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/90842/original/image-20150805-22488-1ak2s3p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/90842/original/image-20150805-22488-1ak2s3p.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">How do you get mosquitoes to spit on a card? Easy. Just coat it with honey.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/jason-riedy/16037303758/in/photolist-qranFd-6TMT1D-6E2z8i-CcPuv-7gTqzK-feqspn-2rfBz9-nJ9epV-81EBzR-eqQC6u-hotMJ5-6ZtgtR-a3SSh4-abckV9-65uHZk-7DToxm-aNKMLF-56Qd3K-9DPg6i-dbkD2m-7YwMbg-r6jKrj-4JMsmv-cQoLed-7gyJkP-a5b4w7-cXTumd-bz6AkW-vfqcME-5ayCeu-g8NVi5-5ocU9G-n2VvW-4YTkB1-YeDAs-CcP5D-8MyuKE-s3KBaG-4951yv-o2LCSy-6E2yf2-a7ypHU-jq9DFa-7PqSWm-awea63-rtgBK1-68hSMD-5V75sU-8MyuxW-omNZvj">Jason Riedy/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>But how do you get a mosquito to give a saliva sample? Easy. Just coat the card in honey and the mosquito will happily spit while getting a sugar fix. Only mosquitoes with virus in their saliva (rather than in their gut) are detected, thus identifying only the most dangerous (infectious-disease-carrying) mosquitoes. </p>
<p>Thousands of mosquitoes can spit on a single card, meaning much less time and money spent in the lab. And there’s no need for expensive shipments of live mosquitoes. What’s more, the cards can be shipped without refrigeration, making surveillance in remote areas far more effective. </p>
<h2>Understanding viral ecology</h2>
<p>Initial field trials <a href="http://online.liebertpub.com/doi/abs/10.1089/vbz.2013.1373">in Queensland and then the Northern Territory</a> showed viruses could be collected in the field. The idea is now being rolled out in <a href="http://medent.usyd.edu.au/arbovirus/results/virusisolates.htm">New South Wales</a>, Western Australia and South Australia. </p>
<p>In 2014, an existing mosquito surveillance <a href="http://www.unisa.edu.au/Global/Health/Sansom/Documents/SAMIR%20Virus%20detection%20info%20Mar%202014.pdf">trapping program</a> in South Australia was modified to retrofit mosquito traps with “honey cards”. When traps were picked up from the field, mosquitoes inside could be seen feeding on the cards. The traps were kept in the lab for a few more days, making sure every mosquito had a chance to provide a saliva sample.</p>
<p>Three virus types (Ross River, Barmah Forest, Stratford) were <a href="http://online.liebertpub.com/doi/abs/10.1089/vbz.2014.1759">detected 18 times</a> in the Adelaide region and in River Murray towns, in a year with very little human disease and only moderate mosquito numbers. Sometimes virus was detected in traps with only a small number of mosquitoes present. </p>
<p>This research showed there was perhaps more virus circulating in urban areas than we first realised, and that our understanding of what leads to large disease outbreaks is poorly developed. What we still don’t know is how much virus circulation is “normal”. And how much virus we need to find before sounding the alarm. </p>
<p>Honey cards collecting mosquito spit have the potential to change our perspective on mosquito-borne disease transmission and open up new avenues for enhanced surveillance strategies. Other mosquito-borne viruses such as <a href="http://www.health.gov.au/internet/main/Publishing.nsf/Content/cdi3702f">chikungunya</a> and <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4055592/">zika</a> are now threatening Australia, but our surveillance of them is poorly developed. </p>
<p>Using mosquito spit tests could enable early detection of these viruses. And this could help safeguard us from incursions of diseases not yet transmitted here.</p><img src="https://counter.theconversation.com/content/42402/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Craig Williams receives funding from SA Health, various local governments in SA, and the Adelaide and Mt Lofty Ranges Natural Resource Management Board. Craig is a member of the National Arbovirus and Malaria Advisory Committee for the Department of Health and Ageing.</span></em></p><p class="fine-print"><em><span>Emily Johnston Flies receives funding from The Royal Society of South Australia and the University of South Australia.</span></em></p>We monitor mosquitoes to help predict and control virus outbreaks. And a new technique for collecting mosquito saliva from the field has made the process both more sensitive and inexpensive.Craig Williams, Associate professor in Biology, University of South AustraliaEmily J Flies, PhD student in Disease Ecology, University of South AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/443972015-07-10T05:25:42Z2015-07-10T05:25:42ZEnjoying the weather? Well look out, mosquitoes love it too<figure><img src="https://images.theconversation.com/files/87910/original/image-20150709-10895-185sdi7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Which way to the bar?</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>A hot summer brings out the sunglasses, ice cream and <a href="https://theconversation.com/are-you-beach-feet-ready-42982">bare feet</a>. Unfortunately it also brings out the flying, biting pests. The UK has <a href="http://www.dipteristsforum.org.uk/">7,000 species</a> of flies, including midges, horse flies and the ones with arguably the worst reputation, mosquitoes.</p>
<p>The most common mosquito species in the UK is <em>Culex pipiens</em>. Few people are actually bitten by it, since it mainly feeds on birds, but this year there are <a href="http://metro.co.uk/2015/06/08/its-going-to-be-a-scorching-summer-and-that-means-more-mosquitoes-5236245/">likely to be more</a> <em>C. pipiens</em> and other mosquito species than usual. This is down to seasonal conditions. Pregnant female mosquitoes hibernate and the mild winter will have resulted in greater survival – and more eggs. A wet May was ideal for the aquatic larvae. A hot summer means more fly activity and more people outside to be bitten. So the cycle continues. </p>
<p>Mosquitoes have needle-like mouth parts that pierce flesh so they can suck blood. They also secrete anticoagulants that prevent clotted blood blocking their mouth parts, and a local anaesthetic so you can’t feel the bite. But these bites aren’t just annoying – they’re potentially deadly.</p>
<p>Mosquito saliva can be a vehicle for transmission of diseases such as malaria, caused by a tiny protozoan organism called Plasmodium. In 2013, between 124m and 283m people contracted the disease and an estimated <a href="http://www.who.int/mediacentre/factsheets/fs094/en/">584,000 people died from it</a>.</p>
<p>As well as malaria, mosquitoes can transmit viruses including dengue fever, yellow fever, West Nile virus and chikungunya. Luckily for the UK, the species that carries most of these diseases, <em>Aedes egypti</em>, doesn’t live here, but it is increasing its range. It recolonised Madeira in 2004-2005 and <a href="http://ecdc.europa.eu/en/healthtopics/vectors/mosquitoes/Pages/aedes-aegypti.aspx#sthash.GEglDxuy.dpuf">there are concerns</a> that it could be transported to western European countries.</p>
<h2>Malaria in the past</h2>
<p>There are very few recent cases of malaria transmission in the UK, although <a href="http://pmj.bmj.com/content/80/949/663.full">there is evidence</a> for the disease’s presence from the 14th to the 17th centuries. Shakespeare even mentioned it in The Tempest. Malaria in the UK <a href="http://e-m-b.org/sites/e-m-b.org/files/European_Mosquito_Bulletin_Publications811/EMB01/EMB01_05.pdf">virtually died out</a> by the end of the 19th century due to a combination of marsh drainage, use of quinine and better sanitation. </p>
<p>Aside from this, the absence of malaria in Western Europe is most likely due to its climate. Plasmodium needs a sustained high temperature to complete its reproduction in the mosquito. The lack of the species mainly involved in transmission of the disease is also crucial. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/87914/original/image-20150709-10876-1j6nr9o.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/87914/original/image-20150709-10876-1j6nr9o.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=264&fit=crop&dpr=1 600w, https://images.theconversation.com/files/87914/original/image-20150709-10876-1j6nr9o.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=264&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/87914/original/image-20150709-10876-1j6nr9o.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=264&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/87914/original/image-20150709-10876-1j6nr9o.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=332&fit=crop&dpr=1 754w, https://images.theconversation.com/files/87914/original/image-20150709-10876-1j6nr9o.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=332&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/87914/original/image-20150709-10876-1j6nr9o.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=332&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Malaria free for how long?</span>
</figcaption>
</figure>
<p>However, the UK’s freedom from dangerous mosquitoes could be set to change. Firstly, with increased globalisation and faster transport, non-native species could be introduced in sufficient numbers to establish a breeding population.</p>
<p>Most insects are strongly “r-selected”, meaning they have evolved to produce large numbers of offspring but live relatively short lives. That means once a species has established itself in a location it can increase very rapidly. For example, Harlequin ladybirds spread over <a href="https://www.buglife.org.uk/bugs-and-habitats/harlequin-ladybird">most of southern Britain</a> in just 10 years, with a much slower breeding rate than mosquitoes.</p>
<p>Secondly, temperatures are predicted to increase due to climate change. A review published in <a href="http://bit.ly/1Hv1vtS">The Lancet Infectious Diseases</a> concludes that warmer conditions and more rainfall could provide the right conditions for disease carrying mosquitoes to arrive in the UK. Existing species such as the common <em>Culex pipiens</em>, could spread West Nile Virus here. Another virus-carrying species, <em>Culex modestus</em> has <a href="http://www.parasitesandvectors.com/content/5/1/32">already established colonies</a> in the Thames estuary.</p>
<h2>Tiger mosquitoes</h2>
<p>A further problem is the Asian tiger mosquito (<em>Aedes albopictus</em>), which spreads dengue fever and chikungunya. Both can be serious illnesses and have no effective treatment. This mosquito’s spread, especially in the United States, has been exacerbated by the international trade in used tyres, whose colour and structure provide ideal incubation pools for the species’ aquatic larvae.</p>
<p>Predictions based on a 2<sup>o</sup>C temperature rise – the <a href="https://theconversation.com/two-degrees-how-we-imagine-climate-change-18035">commonly agreed limit</a> before which “dangerous” climate change will kick in – could extend Tiger mosquitoes’ activity season by a month and its range by up to 30% by 2030. In the past 10 years insect-borne diseases have spread within Europe, including Greece (malaria) West Nile virus (Eastern Europe), Italy and France (chikungunya). This temperature rise could lead to <a href="http://press.thelancet.com/vectorbornedisease.pdf">outbreaks of chikungunya</a> in south-eastern England by the second half of the century.</p>
<p>So as the climate warms, mosquitoes in the UK may no longer be just a pest that gets worse during the occasional heatwave. They may become a widespread, constant and dangerous health threat.</p><img src="https://counter.theconversation.com/content/44397/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christopher Terrell Nield 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 UK’s recent heatwave is perfect for mosquito breeding but something far more dangerous may be coming.Christopher Terrell Nield, Principal lecturer, bioscience, Nottingham Trent UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/442352015-07-03T05:45:50Z2015-07-03T05:45:50ZNorthern development plan shows Australia’s fraught vision of our tropics<figure><img src="https://images.theconversation.com/files/87268/original/image-20150703-30171-1b2zgbo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An historian reading the government White Paper on developing northern Australia will realise we’re actually heading all the way back to the 1890s.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/lawson_matthews/2415335571/">andrew matthews/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><blockquote>
<p>Australia is a big blank map, and the whole people is constantly sitting over it like a committee, trying to work out the ways to fill it in.</p>
</blockquote>
<p>Written as long ago as 1911, the <a href="http://trove.nla.gov.au/work/10819532">words of journalist C.E.W. Bean</a>, later inventor of the Anzac legend, haunted me as I read <a href="https://northernaustralia.dpmc.gov.au/sites/default/files/papers/northern_australia_white_paper.pdf">Our North, Our Future</a>, the federal government’s White Paper on developing northern Australia, released on June 17, 2015. </p>
<p>For more than 100 years, white Australians have rallied to cries of northern development, obsessively figuring out how to fill in the country north of Capricorn lest Asians should come and take it or Aborigines reclaim it. </p>
<p>Indeed, the first medical research organisation, the Australian Institute of Tropical Medicine (AITM), was set up in Townsville in the decade after federation in order to <a href="https://dukeupress.edu/The-Cultivation-of-Whiteness/index-viewby=title&sort=.html">ascertain whether a working white race</a> might be implanted across our tropical territory. Or whether moist heat would sap the vitality and mentality of whites, and tropical germs destroy them.</p>
<p>One of its later directors, Raphael Cilento, a very proud white man and anti-Semite, spent his career in “the struggle to establish a tropical consciousness in Australia” — as he put it in the Queensland school text he wrote with Clem Lack, <a href="http://www.textqueensland.com.au/item/book/1e6ed5d19fc3219033ff9a76eff6a190">Triumph in the Tropics</a>. </p>
<h2>A veritable goldmine</h2>
<p>Consistent with the barrage of tropical boosterism, the current government wants yet again to unlock the potential of the North and settle millions of productive citizens above Capricorn. Only it’s inclined now to bang on about fostering a multi-racial economic powerhouse rather than making the world safe for virile white labourers. </p>
<p>Thus the government is planning, inaptly, to use “Australia Unlimited branding to showcase investor ready projects and specific northern opportunities” — surely unaware that novelist E.J. Brady, who coined the term <a href="http://trove.nla.gov.au/work/8621138?selectedversion=NBD2972726">Australia Unlimited</a>, hoped the Australian tropics would be purely white and free of pesky Aborigines and Chinese.</p>
<p>Indeed, “unlimited for whom?” is always an apposite question in the history of Australian nationalism.</p>
<p>As an historian of medicine, I found the White Paper’s emphasis on tropical health particularly intriguing. A Tropical Health Strategy is a key part of this ambitious plan to develop what may be called <a href="http://www.harpercollins.com.au/9780730408871/capricornia">Capricornia</a> (following the lead of novelist Xavier Herbert). </p>
<p><a href="https://northernaustralia.dpmc.gov.au/sites/default/files/papers/northern_australia_white_paper.pdf">Our North, Our Future</a> suggests two compelling reasons for building expertise in tropical medicine. Investment in research into “tropical” diseases, such as dengue fever, malaria, melioidosis, Australian bat lyssavirus, Hendra virus, Nipah virus, chikungunya, Murray Valley encephalitis, multidrug-resistant tuberculosis and “other emerging pathogens” would, the report says, make Australia “a leading hub for the development of tropical medicine”. </p>
<p>The federal government has <a href="http://trademinister.gov.au/releases/Pages/2015/ar_mr_150510.aspx">allocated A$6.9 million for basic research</a> on such “priority diseases” — many of them dubiously tropical, but obviously worth treating all the same. And found a further A$8.5 million to “commercialise research in new tropical therapeutics and diagnostics”.</p>
<p>Understandably, Louis Schofield, the director of the Australian Institute of Tropical Health and Medicine, a reinvention of the AITM (but note the tactful insertion of health), has welcomed the investment. </p>
<p>“By promoting commercialisation and the creation of science/industry networks,” <a href="http://www.jcu.edu.au/research/JCU_147417.html">Professor Schofield announced</a>, “this funding initiative plays to Australia’s scientific strengths in the future economy of the Pacific Rim.”</p>
<h2>Pharmaceutical cashcow</h2>
<p>The government’s obsession with commercial opportunities in alleviating tropical disease is revealing. Certainly, it fits with technocratic, disease-centred, top-down programs of global health organisations such as the Bill and Melinda Gates Foundation. </p>
<p>“In calling the world’s researchers to develop innovative solutions to ‘the most critical challenges in global health’,” writes <a href="http://www.thelancet.com/pdfs/journals/lancet/PIIS0140673605664793.pdf">public health researcher Anne-Emanuelle Birn in The Lancet</a>, “the Gates Foundation has turned to a narrowly conceived understanding of health as product of technical interventions divorced from economic, social, and political contexts.” </p>
<p>But Australia’s Tropical Health Strategy goes further, hoping to profit from such technical fixes. This reveals a sort of cargo-cult mentality: build the laboratories and commercial medical technologies will pile up, solving the problems of global disease and making us rich as well. </p>
<p>In <a href="https://muse.jhu.edu/journals/hum/summary/v001/1.1.lakoff.html">an influential 2010 article</a>, anthropologist Andrew Lakoff describes “two regimes of global health”: what drives global health, he argues, is either concern with biosecurity, with emerging disease threats, or the humanitarian engagement of organisations like Médecins sans Frontières, which seeks to relieve suffering.</p>
<p>Naively, Lakoff failed to account for the “vision” of money-rubbing Australian politicians who imagine tropical medicine simply as a cash cow — or should that be a cash mosquito?</p>
<h2>Biosecurity fears</h2>
<p>Biosecurity is not forgotten, of course — how could it be in contemporary Australia? Apart from lucrative returns, the other main reason we should invest in tropical medicine, according to the White Paper, is to safeguard the nation from the threat of introduced diseases and pests. </p>
<p>Of course, this is an old saw, dating back to the first AITM: we must be vigilant against foreign bugs and the foreigners who spread them. We are told that “the Asia-Pacific region is a global epicentre for emerging infectious diseases and drug resistance”. </p>
<p>We are reminded that “the North’s proximity to our international neighbours, extensive coastline and sparse population makes it particularly vulnerable to biosecurity threats”. </p>
<p>Almost 100 years ago, Anton Breinl, the first director of the AITM, assured nationalist politicians that there was nothing inherently pathogenic in the tropics for whites. Rather, <a href="https://www.dukeupress.edu/The-Cultivation-of-Whiteness/index-viewby=title.html">they must protect vulnerable Europeans</a> from coloured races on the margins of Australia who had a proclivity for carrying germs especially noxious to white people. This was the medical rationale for immigration restriction.</p>
<p>The authors of this White Paper still seem to assume that disease comes from outside our borders, even if many of their “priority diseases”, such as Hendra, are in fact vernacular phenomena, genuine little Aussie battler viruses. </p>
<p>Now, I’m not denying there are frightening diseases emerging beyond our borders — just that in focusing exclusively on foreign threats we unrealistically limit the epidemiological palette. Evidently, in the biosecurity industry it’s hard to break such disabling xenophobic habits.</p>
<h2>The power of medicine</h2>
<p>If the White Paper is a reliable guide, tropical medicine is more important than ever in northern development. It has a timeworn contribution to make in securing us against disease threats, and an increasing role to play in generating pharmaceutical products and profits. </p>
<p>The authors express a touching confidence in tropical medicine, a faith in its efficacy that would have embarrassed even Breinl and Cilento. Indeed, so effective is modern tropical medicine that we can now allow those supposedly dodgy, previously disease-dealing foreigners within our borders to labour in the tropics. </p>
<p>Thus the White Paper recommends Designated Area Migration Agreements (DAMA) to permit foreign skilled and semi-skilled workers into a few northern zones. It promotes the <a href="https://employment.gov.au/seasonal-worker-programme">Seasonal Worker Programme</a> for labourers from the Pacific Islands and Timor Leste, as well as a new pilot program for workers from Kiribati, Nauru and Tuvalu. </p>
<p>A few pages earlier, these people and the places they come from were stigmatised as biosecurity risks, but presumably our tropical medicine industry can render them secure. Once used to justify keeping Asians and Pacific Islanders out of Australia, tropical medicine will now be employed to bring them in “safely”.</p>
<p>Too often, members of the infamous leftie lynch mob and other vaguely ABC-types protest that prime minister Tony Abbott is taking us back to the 1950s. But any Australian historian reading this White Paper will realise we’re actually heading all the way back to the 1890s, before federation, when unbridled capitalism and various forms of indentured labour were developing our North.</p>
<p>“Whose North?” we should ask, “whose triumph?”</p><img src="https://counter.theconversation.com/content/44235/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Warwick Anderson 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 federal government’s recent White Paper on developing northern Australia has disturbing echoes of the 1890s, a time when unbridled capitalism and indentured labour developed the North.Warwick Anderson, Professorial Research Fellow, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/420172015-06-19T05:06:21Z2015-06-19T05:06:21ZThe massive waste happening in mosquito-borne disease research<figure><img src="https://images.theconversation.com/files/85404/original/image-20150617-23223-1y0ihsi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A global killer – we need to use all the resources we can get. </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/cdcglobal/9661967327/in/photolist-fHN7gz-98661E-7Wp64W-7WpacE-4TGLiQ-8UAc6E-7WkPV8-qdisTZ-7WkT12-7Wp8rh-7WkPKR-7Wpax5-7WkVWr-7Wp5R3-7Wp7Am-7Wp6uj-7Wp7iC-7WkRPT-7WkPsg-7WkU7K-7WkMMr-9Bzc3p-9Bzc7D-9BzbUg-9BzbYg-eQtqvQ-fbAnvi-7Cq7NA-8jdEzo-fbQCCf-fbQCCu-fbAnvt-fbQCEC-fbQCFS-ojLbmG-fbAmFv-5KmsAb-8GVyN3-4eGFwr-4eGFuv-8VMxE1-nGYKh5-9LudxV-8GSq58-8GSpRZ-4eLDpU-9AFBWn-9AFBF6-bBFHUY-6otX1z">CDC Global</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Nearly two-thirds of the world’s population are at risk from vector-borne diseases – diseases transmitted by bites from infected insects and ticks. The most deadly of these is malaria which causes nearly <a href="http://www.who.int/malaria/publications/world_malaria_report_2014/en/">600,000 deaths</a> each year, mostly in young children in Africa. Much has been done to tackle this disease, but <a href="http://dx.doi.org/10.1016/j.pt.2015.04.015">research</a> we’ve published in Trends in Parasitology suggests that the poorly designed field trials are causing a massive waste of financial resources.</p>
<p>Over the past ten years there have been <a href="http://www.who.int/malaria/publications/world_malaria_report_2014/en/">massive declines</a> in malaria due to the scaling-up of control programmes using <a href="http://www.cdc.gov/malaria/malaria_worldwide/reduction/itn.html">long-lasting insecticide treated nets</a> and <a href="http://www.africairs.net/about/indoor-residual-spraying/">spraying of insecticides</a> inside the house, along with advances in diagnosis and treatment. However, a number of challenges to effective control exist, <a href="http://www.who.int/malaria/areas/vector_control/insecticide_resistance/en/">including insecticide resistance</a>. </p>
<p>Other vector-borne diseases, <a href="http://www.nathnac.org/pro/factsheets/dengue.htm">dengue</a> and <a href="http://www.cdc.gov/chikungunya/">chikungunya</a> are increasing globally; high-profile outbreaks were reported <a href="http://www.nytimes.com/2014/02/09/world/americas/virus-advances-through-east-caribbean.html?_r=0">in the Caribbean</a> in 2014 <a href="http://www.economist.com/news/americas/21647306-welcome-return-wet-weather-has-nasty-side-effect-when-it-rains-it-pours">and Brazil</a> earlier this year. These debilitating diseases have no effective treatment – and currently the only method of prevention is by controlling the mosquitoes, mainly through treating or removing containers such as water butts which provide attractive breeding sites. </p>
<p>It is widely recognised that new tools to control mosquitoes are urgently needed to control these diseases. These tools must follow a lengthy development process to ensure they are both effective and safe. Before new interventions can be used in the field, the evidence from laboratory studies and field trials needs to be reviewed <a href="http://www.who.int/malaria/mpac/en/">by policy-making committees</a> at the World Health Organisation. </p>
<h2>Repeated problems</h2>
<p>Through our research we have identified repeated problems with vector control field trials which mean that the results of many studies are invalid or biased. The problem of <a href="http://www.researchwaste.net/">waste in research design and conduct</a> has been highlighted in a Lancet series in 2014 and it is estimated that <a href="http://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2809%2960329-9/fulltext?_eventId=login">an astonishing 85% of research investment is wasted</a> due to poor design, conduct or reporting of studies, or studies that ask the wrong question. We estimate that the average malaria field trial costs about £500,000 to £1m so this represents a massive waste of financial resources.</p>
<p>A key problem we identified is that many vector control studies assess the ability of the intervention to kill or reduce the insect but do not look at how effective these interventions are in reducing disease and saving people’s lives. Evidence of an effect on people’s health is essential to demonstrate that methods for controlling insects have public health benefits. </p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/85408/original/image-20150617-23252-qckt26.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/85408/original/image-20150617-23252-qckt26.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=561&fit=crop&dpr=1 600w, https://images.theconversation.com/files/85408/original/image-20150617-23252-qckt26.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=561&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/85408/original/image-20150617-23252-qckt26.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=561&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/85408/original/image-20150617-23252-qckt26.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=705&fit=crop&dpr=1 754w, https://images.theconversation.com/files/85408/original/image-20150617-23252-qckt26.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=705&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/85408/original/image-20150617-23252-qckt26.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=705&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Mosquito pupae emerging.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/usgsbiml/9764583566/in/photolist-fSS3v5-da3Lgi-5us7yz-4Rd3p3-bEw8gp-7AAjBT-jL7UU-duwjtk-rgSx2X-8edQtM-4WoMWU-eDLJGD-3kffcd-8DKdaB-f5qRN-fQnZtM-2sSN3-fQnYZz-fQnZng-66bife-6sp9Di-8eh6Q9-8eh7ds-o5kiif-ajNQw2-897KEC-nXaYr8-894vRi-ekbqWM-7zdm6o-a5FMNo-qUDuY5-8dCqEk-eDqus9-25MhR3-6GMpYX-rZbdF4-8WBGoe-9kKnya-okzDVK-o4oKNv-8WEKJq-aeFx6V-a1XCDk-z6hv-7DeBBw-stKUrP-ajNQqB-o66Ui9-hiRQbp">USGS Bee Inventory and Monitoring Lab</a></span>
</figcaption>
</figure>
<p>For example, <a href="http://www.cochranelibrary.com/enhanced/doi/10.1002/14651858.CD008090.pub2">a review looking at</a> how effective fish that eat mosquito larvae can be in controlling malaria did not find any studies with health outcomes and was unable to say if reductions in larvae translated into fewer cases of malaria in people.</p>
<p>A large number of vector control trials <a href="http://www.medicine.ox.ac.uk/bandolier/booth/glossary/RCT.html">are also not randomised</a> – so participants are not randomly allocated to receive intervention or control – which can result in bias. Making sure that participants and healthcare providers are not aware of which intervention they have received (<a href="http://www.medicine.ox.ac.uk/bandolier/booth/glossary/blind.html">blinding</a>) can prevent bias. For example, healthcare providers may be more likely to diagnose malaria if they are aware that a patient is in the control group of a vector control study, compared to a patient who has received a new type of long-lasting insecticide treated net. </p>
<p>Many of the issues we identified could be easily remedied, for example through the use of standardised health outcomes to assess the effectiveness of new interventions, randomisation and blinding. These are <a href="http://www.nhs.uk/Conditions/Clinical-trials/Pages/Fairtests.aspx">features of clinical trials</a> that are conducted as standard when testing new drug treatments, but are often overlooked for vector control trials. </p>
<p>A possible reason for this is that medical entomologists (people who study disease vectors) have typically worked in silos and are not familiar with rigorous methods for designing intervention studies. Many trials have been also conducted in resource-limited settings where often the urgent need for disease control means that research design is not a priority. </p>
<p>In future, we recommend the definition of clear guidelines to support the rigorous design and conduct of vector control trials and increased training for medical entomologists. This is imperative, not only to prevent waste of human and financial resources, but also to speed up the roll-out of new tools in the field so we can save more lives from these types of diseases.</p><img src="https://counter.theconversation.com/content/42017/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Anne Wilson receives funding from The Bill & Melinda Gates Foundation</span></em></p>Investment in insect-borne disease field trials is being wasted by poor study design.Anne Wilson, PhD Candidate and Research Assistant, Durham UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/391762015-04-02T23:05:44Z2015-04-02T23:05:44ZIs climate change to blame for outbreaks of mosquito-borne disease?<figure><img src="https://images.theconversation.com/files/76860/original/image-20150402-31268-1wwzjri.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A changing climate may contribute to more mosquito-borne disease, but it doesn't guarantee it.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/13105441@N04/1368626064">john dunstan/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>The east coast of Australia is currently experiencing one of its worst outbreaks of mosquito-borne disease in years. Mosquitoes have plagued the summer and now there’s a <a href="http://www.couriermail.com.au/news/queensland/queenslands-worst-ross-river-virus-outbreak-in-almost-20-years-hits-brisbane/story-fnn8dlfs-1227261900933">dramatic increase</a> in disease caused by Ross River virus, spread by the bite of mosquitoes.</p>
<p>Mosquitoes need blood and, unfortunately, they often bite people to get it – <a href="https://theconversation.com/health-check-why-mosquitoes-seem-to-bite-some-people-more-36425">some more than others</a>. </p>
<p>Pathogens spread by mosquitoes already kill <a href="https://theconversation.com/when-it-comes-to-natures-public-enemy-number-one-the-mosquito-is-a-modern-monster-39214">more than a million people a year</a> across the world, mostly in tropical regions. The increased <a href="http://www.biomedcentral.com/1471-2334/14/167">risk of mosquito-borne disease</a> in a warmer, wetter world is a concern for health authorities internationally. </p>
<p>But more mosquitoes doesn’t guarantee more mosquito-borne disease. If it isn’t the “right” mosquito, there won’t be outbreaks of dengue or malaria. </p>
<p>And while a changing climate may contribute to more mosquito-borne disease, it doesn’t guarantee it: human movement around the world is likely to play just as an important a role.</p>
<h2>Not all mozzies are equal</h2>
<p>Mosquitoes aren’t like dirty syringes spreading infected blood. They’re diverse and complex creatures that have a special relationship with the parasites and viruses they can spread.</p>
<p>Very few of the thousands of mosquitoes found on earth are able to spread <a href="https://theconversation.com/explainer-what-is-dengue-fever-8571">dengue</a> or <a href="https://theconversation.com/explainer-the-chikungunya-virus-and-its-risk-to-australia-16968">chikungunya</a> viruses. A different group are involved in the spread of <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3990373/">West Nile virus</a> and <a href="http://www.cdc.gov/japaneseencephalitis/">Japanese encephalitis virus</a>, while a different type of mosquito altogether is involved in <a href="http://www.who.int/topics/malaria/en/">spreading malaria</a> parasites. </p>
<h2>Human movement</h2>
<p>A recent article in the journal <a href="http://www.thelancet.com/journals/laninf/article/PIIS1473-3099%2815%2970091-5/abstract">Lancet Infectious Diseases</a> reviews the factors contributing to future increases in mosquito-borne disease risk in the United Kingdom. While the authors identify increased temperatures as potentially providing suitable conditions for mosquitoes that spread pathogens, climate change alone wasn’t enough. </p>
<p>The mosquitoes that can spread dengue and chikungunya viruses, particularly the Asian Tiger Mosquito (<em>Aedes albopictus</em>), need to get there in the first place and, most likely, that is with people and their belongings. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/76043/original/image-20150325-12293-1880cs9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/76043/original/image-20150325-12293-1880cs9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=386&fit=crop&dpr=1 600w, https://images.theconversation.com/files/76043/original/image-20150325-12293-1880cs9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=386&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/76043/original/image-20150325-12293-1880cs9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=386&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/76043/original/image-20150325-12293-1880cs9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=485&fit=crop&dpr=1 754w, https://images.theconversation.com/files/76043/original/image-20150325-12293-1880cs9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=485&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/76043/original/image-20150325-12293-1880cs9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=485&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Asian Tiger Mosquito.</span>
<span class="attribution"><span class="source">SteveDoggett</span></span>
</figcaption>
</figure>
<p>It isn’t only the UK that is at risk. Until recently, chikungunya virus was unknown from the Americas but within a year of it being introduced into the Caribbean, it had spread to both North America and South America and is <a href="http://www.cdc.gov/chikungunya/geo/">suspected to have infected</a> over 1.2 million people.</p>
<p>As the researchers highlight, even the way authorities respond to the threats of climatic change, such as the construction or rehabilitation of wetlands <a href="http://www.nature.com/nclimate/journal/v3/n10/abs/nclimate1944.html">to create a buffer</a> against increasingly frequent storms and sea level rise, may further increase risk. Mosquitoes that spread West Nile virus could move into these wetlands.</p>
<h2>Hitching a ride to Australia</h2>
<p>The Asian Tiger Mosquito poses a significant threat to Australia. It was discovered in the <a href="http://www.bioone.org/doi/abs/10.2987/8756-971X%282006%2922%5B358:DOAWIO%5D2.0.CO%3B2">Torres Strait in 2005</a>, having thought to have hitchhiked on <a href="http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0002361">fishing boats from Indonesia</a>. Its a question of when, not if, this mosquito will make its way to mainland Australia.</p>
<p>The mosquito has already hitchhiked to Europe and North America with eggs attached to used tyres and lucky bamboo. Movement of people, not shifts in climate is the biggest risk. </p>
<p>Should it reach one of our major cities, <a href="http://onlinelibrary.wiley.com/doi/10.1111/aec.12105/abstract">there is little doubt</a> that mosquito could become a <a href="http://jme.oxfordjournals.org/content/early/2015/03/05/jme.tjv004">persistent summer pest</a> and <a href="http://jme.oxfordjournals.org/content/51/3/661">possible public health threat</a>. The way we respond to water shortages in our cities, <a href="http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0000429">by increasing water storage around our homes</a>, may set the scene for this mozzie to move in.</p>
<h2>Aussie mozzie risks</h2>
<p>Exotic mosquitoes and viruses are a concern but there are still plenty of ways a local mosquito bite can make you sick. </p>
<p><a href="https://theconversation.com/explainer-what-is-ross-river-virus-24630">Ross River virus</a> is the most commonly reported local mosquito-borne disease. Every year about 5,000 fall ill due to this virus. While not fatal, it can cause fever, rash, headache, joint pain and fatigue that may last a few weeks or many months. It can be seriously debilitating. </p>
<p>By the end of March, New South Wales and Queensland will have <a href="http://www9.health.gov.au/cda/source/rpt_4.cfm">recorded over 4,700 cases</a> of Ross River virus disease. Those figures already exceed the total number of cases reported in each of the previous three to five years. This may be the biggest outbreak of mosquito-borne disease along the east coast of Australia since the mid-1990s.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/76862/original/image-20150402-31316-1prg481.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/76862/original/image-20150402-31316-1prg481.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/76862/original/image-20150402-31316-1prg481.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/76862/original/image-20150402-31316-1prg481.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/76862/original/image-20150402-31316-1prg481.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/76862/original/image-20150402-31316-1prg481.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/76862/original/image-20150402-31316-1prg481.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">Kangaroos and wallabies also carry the Ross River virus.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/thorstenrinne/4492591283">Thorsten Rinne/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<p>Australia has had <a href="https://www.mja.com.au/journal/2009/190/5/dengue-and-climate-change-australia-predictions-future-should-incorporate">major outbreaks of dengue in the past</a>. But the only mosquito in Australia able to spread the virus is restricted to far north Queensland. It is <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1440-6055.2008.00677.x/full">unlikely to spread</a> to southern cities beyond Brisbane based on temperature change alone.</p>
<p><a href="http://www.health.nsw.gov.au/Infectious/factsheets/Pages/barmah-forest-virus.aspx">Barmah Forest</a>, <a href="https://www.mja.com.au/journal/2012/196/5/murray-valley-encephalitis-review-clinical-features-diagnosis-and-treatment?">Murray Valley encephalitis</a> and <a href="http://www.health.nsw.gov.au/Infectious/factsheets/Pages/Kunjin_virus.aspx">Kunjin</a> viruses are all also spread by mosquitoes in Australia too, although they’re generally far less common that Ross River virus.</p>
<h2>Could the current outbreak be linked to a changing climate?</h2>
<p>Thanks to the <a href="http://www.bom.gov.au/climate/current/statements/scs50.pdf">warmest spring on record</a> and substantial rainfall associated with <a href="http://www.abc.net.au/science/articles/2015/03/25/4201439.htm">tropical cyclones</a>, conditions have been perfect for mosquitoes. If these climatic events become more common, there is little doubt we’ll continue to see outbreaks of Ross River virus disease and other mosquito-borne diseases.</p>
<p>However, outbreaks of Ross River virus are determined by more than mosquitoes. Wildlife play an important role too, as <a href="http://online.liebertpub.com/doi/abs/10.1089/vbz.2014.1617">kangaroos and wallabies that carry the virus</a> are increasingly found close to residential areas. </p>
<p>So understanding and predicting outbreaks requires <a href="http://online.liebertpub.com/doi/abs/10.1089/vbz.2012.1284">an understanding</a> of wetlands and wildlife, as well as climate and mosquitoes. The way we <a href="https://theconversation.com/using-urban-planning-to-reduce-mosquito-borne-disease-8430">guide urban development</a> will also be important.</p>
<p>The current outbreak, however, may provide a glimpse of what lays ahead. With warmer weather, we may see an extension of the “mosquito season” each year. Aside from the risks to public health extending well into autumn (or possibly arriving earlier in summer), there is the increased economic burden on local authorities needing to <a href="http://www.couriermail.com.au/news/queensland/brisbane-city-councils-air-and-land-assault-to-beat-mosquito-plague/story-fnn8dlfs-1227193706970">expand mosquito control</a> and <a href="http://www.theleader.com.au/story/2025003/more-mosquitoes-on-the-way/">disease surveillance programs</a>.</p>
<p>There are still gaps in our understanding of the relationship between climate, mosquitoes and disease. But the current outbreak of Ross River virus disease should serve as a reminder that in the future, more of our “home grown” mosquito-borne disease, and not necessarily the spread of “tropical” disease such as dengue and chikungunya, could be our primary concern.</p><img src="https://counter.theconversation.com/content/39176/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cameron Webb and the Department of Medical Entomology 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>The east coast of Australia is currently experiencing one of its worst outbreaks of mosquito-borne disease in years.Cameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of SydneyLicensed as Creative Commons – attribution, no derivatives.