tag:theconversation.com,2011:/ca/topics/mosquito-borne-diseases-4336/articlesMosquito-borne diseases – The Conversation2023-11-22T14:35:36Ztag:theconversation.com,2011:article/2168382023-11-22T14:35:36Z2023-11-22T14:35:36ZPatients’ beliefs about illness matter: the case of elephantiasis in rural Ghana<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 areas of Ghana where a mosquito-borne disease called <a href="https://www.who.int/news-room/fact-sheets/detail/lymphatic-filariasis#:%7E:text=Lymphatic%20filariasis%2C%20commonly%20known%20as,damage%20to%20the%20lymphatic%20system">lymphatic filariasis</a>, often referred to as elephantiasis, continues to spread. </p>
<p>Lymphatic filariasis, or LF as it is commonly known, is a neglected tropical disease which spreads through repeated bites by parasite-carrying mosquitoes. This infection results in the painful and debilitating swelling of legs, arms and genitals, and increases vulnerability to injury and secondary infections. </p>
<p>Although little known, lymphatic filariasis is a <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3246437">significant</a>
and <a href="https://www.thelancet.com/journals/langlo/article/PIIS2214-109X(20)30323-5/fulltext">under-addressed</a> global cause of disability. According to the World Health Organization at least<a href="https://www.who.int/news-room/fact-sheets/detail/lymphatic-filariasis"> 51 million</a> people are infected with lymphatic filariasis. </p>
<p>The World Health Organization’s <a href="https://www.who.int/teams/control-of-neglected-tropical-diseases/lymphatic-filariasis/global-programme-to-eliminate-lymphatic-filariasis">Global Programme for Elimination of Lymphatic Filariasis</a> has greatly reduced the burden of the disease through preventive mass drug campaigns, mosquito control, veterinary public health and sanitation and hygiene measures.</p>
<p>Despite this concerted effort, however, lymphatic filariasis continues to be endemic and require mass drug administration in <a href="https://academic.oup.com/inthealth/article/13/Supplement_1/S22/6043665">31</a> African countries. The challenges to eradicating it are not well understood, and may hinge on better understanding how people with this disease view their condition. </p>
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Read more:
<a href="https://theconversation.com/why-its-hard-to-end-elephantiasis-a-debilitating-disease-spread-by-mosquitoes-166627">Why it's hard to end elephantiasis, a debilitating disease spread by mosquitoes</a>
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<p>Our research team brings together specialists in epidemiology, public health and human rights. In our recently published paper in <a href="https://journals.plos.org/globalpublichealth/article?id=10.1371/journal.pgph.0002476">PLOS Global Public Health</a> we take a different approach to the conventional medical focus that dominates research and interventions for this disease. </p>
<p>We examined the local perceptions and beliefs about the disease
and the personal experiences of those living with it in three rural communities in Ghana’s Ahanta West district. This coastal district in Ghana’s Western Region has a high rate of lymphatic filariasis infection and many people living with advanced stages of the disease. </p>
<p>Members of our research team had worked in this area for more than a decade, establishing the trust relationships that made this research possible.</p>
<p>Our findings may help provide insight into why lymphatic filariasis persists in certain settings and how best to tackle it.</p>
<h2>Cold, rain and curses</h2>
<p>We found that only <a href="https://journals.plos.org/globalpublichealth/article?id=10.1371/journal.pgph.0002476">18%</a> 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 other sources, including spiritual causes (curses, witchcraft, evil spirits), cold or rainy weather, and other illnesses. In subsequent interviews, people described how, from their perspective, they encountered the disease. </p>
<p>One person explained, “When you are cold, then your leg gets swollen.” </p>
<p>Another noted, “There are some who just get jealous of and develop hatred for people for just walking and going about their normal duties and decide that they do not want this person or that person to progress, hence they buy the disease for them spiritually.” They added, “I strongly believe and have the conviction that someone bought mine for me spiritually.”</p>
<p>In contrast with these beliefs, which show very limited overlap with medical explanations, nearly half (<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6709921">45.8%</a>) of respondents reported receiving information about the disease from healthcare workers or drug campaigns. </p>
<p>These findings suggest we need to learn more about local beliefs in health and wellbeing in order to achieve more effective communication with patients. </p>
<p>Our research also demonstrates lymphatic filariasis is not only a medical condition, but also a social and economic one. </p>
<h2>Ashamed and stigmatised</h2>
<p>Almost <a href="https://journals.plos.org/globalpublichealth/article?id=10.1371/journal.pgph.0002476">80%</a> of respondents reported feeling ashamed or stigmatised by their condition. Some said it restricted their social lives and their willingness to go out in public. </p>
<p>Infection also limited the ability to earn a living. More than a third (<a href="https://journals.plos.org/globalpublichealth/article?id=10.1371/journal.pgph.0002476">36.2%</a>) said they could no longer work due to their condition. Many reported a need to depend on others for financial support. </p>
<p>Among those surveyed less than 3% reported that they were “doing well”. </p>
<p>These findings show an urgent need to address the unmet social, mental health and economic impacts of lymphatic filariasis.</p>
<h2>What needs to be done</h2>
<p>Drug campaigns are important but cannot be done in isolation. Existing research shows us that these <a href="https://academic.oup.com/inthealth/article/13/Supplement_1/S55/6043672">are more successful when offered in a broader context of care</a>. </p>
<p>Healthcare workers must be trained to avoid stigmatising patients. But eliminating stigma is not a simple task, nor can it be left to healthcare workers alone.</p>
<p>Further research is needed to better understand local beliefs about lymphatic filariasis, and to understand how stigma affects patients’ access to treatment and quality of life. This must include the strong links between the disease and poverty. </p>
<p>Lymphatic filariasis follows <a href="https://www.who.int/publications/i/item/WHO-IER-CSDH-08.1">the “social gradient”</a>. Those who are poorest are most likely to be affected. Factors associated with poverty increase the chances of being infected and of developing complications. These factors include poor quality housing, limited access to methods of prevention (mosquito nets, good quality footwear), difficulty getting medical care, living in remote rural communities, and working as subsistence farmers.</p>
<p>The disease also pushes poor people <a href="https://bmcpublichealth.biomedcentral.com/articles/10.1186/s12889-021-10170-8">further into poverty</a> as it progresses.</p>
<p>As the number of people affected by it decreases, those who are left behind are more and more likely to be isolated, marginalised, stigmatised and impoverished. </p>
<p>As we argue in a <a href="https://www.taylorfrancis.com/chapters/edit/10.4324/9781003207672-15/examining-research-positionality-understanding-self-first-step-transnational-research-colleen-mcmillan-alexander-kwarteng-kristi-kenyon-mary-asirifi">recent book chapter</a>, these factors underscore the need for interdisciplinary research teams who are able to address lymphatic filariasis holistically. We need an approach that merges healthcare, health promotion, health systems, spiritual beliefs, social and cultural context, gender dynamics and economic impact. </p>
<p>We must put people with lymphatic filariasis – and their dignity – at the centre of research.</p><img src="https://counter.theconversation.com/content/216838/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kristi Heather Kenyon receives funding from the Canadian Institutes for Health Research.</span></em></p><p class="fine-print"><em><span>Alexander Kwarteng receives funding from the Canadian Institutes of Health Research</span></em></p><p class="fine-print"><em><span>Dr Colleen McMillan receives funding from the Canadian Institutes of Health Research. </span></em></p><p class="fine-print"><em><span>Mary Asirifi works for MacEwan University. She receives funding from CIHR. </span></em></p><p class="fine-print"><em><span>Regiane Garcia receives funding from Canadian Health Institutes Research</span></em></p>In rural Ghana, only 18% of patients believe elephantiasis is a disease. Some others think it is caused by curses or even rain. Only by understanding local beliefs can it be treated effectively.Kristi Heather Kenyon, Associate Professor, Human Rights, University of WinnipegAlexander Kwarteng, Senior Lecturer in Immunology of Infectious Diseases, Kwame Nkrumah University of Science and Technology (KNUST)Colleen McMillan, Scientific Co-Director and Associate Professor, University of WaterlooMary Asirifi, Assistant Professor, Department of Nursing Foundations, MacEwan UniversityRegiane Garcia, Research Associate, focus on health rights, laws and policies, Simon Fraser UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2150522023-10-05T04:04:34Z2023-10-05T04:04:34ZNew malaria vaccine: no silver bullet but an important step towards eradication<p>In what was very big news for global health, this week the <a href="https://www.who.int/news/item/02-10-2023-who-recommends-r21-matrix-m-vaccine-for-malaria-prevention-in-updated-advice-on-immunization">World Health Organisation</a> (WHO) recommended a new vaccine for the prevention of malaria in children, called R21/Matrix-M.</p>
<p>Malaria, caused by infection with <em>Plasmodium</em> parasites and transmitted via mosquitoes, still causes many millions of cases and more than <a href="https://www.who.int/teams/global-malaria-programme/reports/world-malaria-report-2022">600,000 deaths annually</a>, the majority in children under five and pregnant women in Africa. </p>
<p>This is the second malaria vaccine to be endorsed by the WHO, following a vaccine called <a href="https://www.who.int/news/item/06-10-2021-who-recommends-groundbreaking-malaria-vaccine-for-children-at-risk">RTS,S/AS01</a> in 2021. </p>
<p>Both are much-needed tools in the global fight to eradicate malaria, with the potential to save millions of lives. But the new vaccine offers some unique advantages.</p>
<h2>First, how the malaria vaccines work</h2>
<p>Both the <a href="https://www.nature.com/articles/srep46621">newly endorsed vaccine</a>, R21, and the <a href="https://www.tandfonline.com/doi/full/10.1080/21645515.2019.1669415">earlier vaccine</a>, RTS,S, aim to protect against malaria by blocking the <em>Plasmodium falciparum</em> parasite before it can cause infection. They do this by targeting the parasite during the bite from a mosquito. </p>
<p>Called “sub-unit” vaccines, they contain a single protein from <em>P. falciparum</em>, the circumsporozoite protein, which coats the surface of the parasite. The vaccines aim to drive an immune response that can subsequently recognise the circumsporozoite protein, and kill the parasite before it causes infection. </p>
<p>It’s a bit like how most COVID vaccines target the “spike” protein, a protein on the surface of SARS-CoV-2 (the virus that causes COVID) to block the virus.</p>
<p>Both malaria vaccines are administered with an adjuvant, a special formula to help activate the immune response. They contain the same parasite protein target, but are designed with different amounts of parasite protein, and unique adjuvants. </p>
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Read more:
<a href="https://theconversation.com/worlds-first-mass-malaria-vaccine-rollout-could-prevent-thousands-of-children-dying-169457">World's first mass malaria vaccine rollout could prevent thousands of children dying</a>
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<h2>Efficacy and access</h2>
<p>New <a href="http://dx.doi.org/10.2139/ssrn.4584076">results</a> from phase 3 trials of R21 show the vaccine can prevent up to 75% of malaria cases over the year following vaccination. This is in areas where malaria occurs seasonally and when the vaccine is used in combination with other preventive measures including drugs. It’s important to note this data has not yet been peer-reviewed.</p>
<p>Peer-reviewed <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(15)60721-8/fulltext">phase 3 trials of RTS,S</a> showed the vaccine can prevent around 56% of cases in the year following vaccination across a large number of malaria infection sites. </p>
<p>These vaccines haven’t been tested directly against each other, so we can’t say conclusively whether one vaccine is more effective than the other, though it seems possible that R21 offers enhanced protection. </p>
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<img alt="A mosquito on skin." src="https://images.theconversation.com/files/552234/original/file-20231005-19-jqtpoy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552234/original/file-20231005-19-jqtpoy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552234/original/file-20231005-19-jqtpoy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552234/original/file-20231005-19-jqtpoy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552234/original/file-20231005-19-jqtpoy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552234/original/file-20231005-19-jqtpoy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552234/original/file-20231005-19-jqtpoy.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">
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<span class="caption">There are more than 600,000 deaths globally from malaria each year.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/dangerous-malaria-infected-mosquito-skin-bite-1483138139">nechaevkon/Shutterstock</a></span>
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<p>R21 also has significant advantages when it comes to manufacturing, supply and cost, with <a href="http://dx.doi.org/10.2139/ssrn.4584076">100-200 million doses</a> predicted to be available annually from existing manufacturers in India. Because of this, and with the ability for manufacturing to be expanded to other malaria-endemic countries, the cost of R21 will be less than <a href="http://dx.doi.org/10.2139/ssrn.4584076">US$5 a dose</a> (compared to only around 15 million doses for RTS,S at nearly <a href="https://www.unicef.org/supply/media/13396/file/Malaria-Vaccine-Supply-Price-Market-Questions-Answers-August2022.pdf">twice the cost</a> per dose). </p>
<p>The availability of the R21 vaccine should make access and rollout across malaria-endemic areas feasible in the coming years.</p>
<h2>Will this vaccine eradicate malaria?</h2>
<p>The short answer is no, but it promises to help a great deal.</p>
<p>Despite the impressive protection reported from the R21 vaccine, challenges remain. The vaccine requires <a href="http://dx.doi.org/10.2139/ssrn.4584076">three doses over three months</a> in the first instance, followed by a booster dose one year later. It also seems likely that yearly boosters will be required to maintain protection. </p>
<p>As we’ve seen in the rollout of COVID vaccines, boosters are challenging to administer even in areas such as Australia with very strong health systems. To date, neither of the malaria vaccines have been integrated within other childhood vaccination programs, placing an additional burden on communities.</p>
<p>Further, R21 is yet to be tested in an area of very high malaria risk. Results from the RTS,S vaccine flag this as a concern, because in areas of high malaria transmission there is a risk that <a href="https://dx.doi.org/10.1126/scitranslmed.aau1458">previous infection</a> can block the efficacy of vaccines, leaving those most at risk with reduced protection.</p>
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<strong>
Read more:
<a href="https://theconversation.com/the-long-road-to-a-new-malaria-vaccine-told-by-the-scientists-behind-the-breakthrough-podcast-214885">The long road to a new malaria vaccine, told by the scientists behind the breakthrough – podcast</a>
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<p>Finally, both endorsed vaccines only target one type of malaria, that caused by <em>P. falciparum</em> parasites. This is the <a href="https://www.who.int/teams/global-malaria-programme/reports/world-malaria-report-2022">most deadly</a> form of malaria, so it’s understandable that vaccine efforts have focused on this species. </p>
<p>But it’s important to note that these vaccines don’t protect against other types of malaria, most especially <em><a href="https://www.vivaxmalaria.org/">Plasmodium vivax</a></em>, which causes the most disease in southeast Asia.</p>
<p>Further research and development will be needed to develop second-generation malaria vaccines. Especially important will be vaccines that induce high levels of sustained protection without the need for yearly boosters, vaccines that protect against all malaria types (particularly <em>P. vivax</em>), and vaccines or additional drugs that can boost protection for children who have the highest malaria risk.</p>
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<img alt="A group of happy African schoolchildren." src="https://images.theconversation.com/files/552237/original/file-20231005-23-9bofx9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552237/original/file-20231005-23-9bofx9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552237/original/file-20231005-23-9bofx9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552237/original/file-20231005-23-9bofx9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552237/original/file-20231005-23-9bofx9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552237/original/file-20231005-23-9bofx9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552237/original/file-20231005-23-9bofx9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">The R21 vaccine will be given to children in countries where malaria is endemic.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-african-schoolgirls-playground-waving-camera-668003338">Monkey Business Images/Shutterstock</a></span>
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<h2>Multiple layers of protection</h2>
<p>While not a silver bullet, the availability of two malaria vaccines is an exciting development. </p>
<p>We’ve seen with the COVID pandemic that vaccines can have a significant individual and public health impact when used alongside other tools. Likewise, it’s essential that malaria control strategies make integrated use of all available interventions. </p>
<p>The use of these two vaccines, with continued use of preventive drugs, insecticide-treated bed nets, fast and effective drug treatments, and other control tools, will make a big difference and save lives.</p>
<p>Many of us in the field wondered if we would ever see an approved malaria vaccine. As WHO director-general <a href="https://www.who.int/news/item/02-10-2023-who-recommends-r21-matrix-m-vaccine-for-malaria-prevention-in-updated-advice-on-immunization">Tedros Adhanom Ghebreyesus said</a>, “As a malaria researcher, I used to dream of the day when we would have a safe and effective vaccine against malaria. Now we have two.”</p><img src="https://counter.theconversation.com/content/215052/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michelle Boyle receives funding from the Snow Medical Research Foundation, CSL, National Health and Medical Research Council, and National Institutes of Health to understand immunity to malaria and to develop approaches of host directed therapies to improve immunity. </span></em></p><p class="fine-print"><em><span>Brendan Crabb and the Institute he leads receives research grant funding from the National Health & Medical Research Council of Australia, the Medical Research Future Fund, DFAT's Centre for Health Security and other Australian federal and Victorian State Government bodies. He is the Chair of The Australian Global Health Alliance and the Pacific Friends of Global Health, both in an honorary capacity. And he serves on the Board of the Telethon Kids Institute, on advisory committees of mRNA Victoria, the Sanger Institute (UK), the Institute for Health Transformation (at Deakin University), The Brain Cancer Centre (Australia), the WHO Malaria Vaccine Advisory Committee; MALVAC, and is a member of OzSAGE and The John Snow Project, all honorary positions.</span></em></p>Currently we see more than 600,000 deaths from this mosquito-borne disease each year. This new vaccine – the second approved to treat malaria – could change things.Michelle Boyle, Snow Medical Fellow & CSL Centenary Fellow, Burnet InstituteBrendan Crabb, Director and CEO, Burnet InstituteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2129552023-09-17T12:07:36Z2023-09-17T12:07:36ZWhat Canadians need to know about West Nile virus, a mosquito-borne infection that can be life-threatening<iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/what-canadians-need-to-know-about-west-nile-virus-a-mosquito-borne-infection-that-can-be-life-threatening" width="100%" height="400"></iframe>
<p>During the late summer of 1999, New York City recorded an <a href="https://doi.org/10.2105%2Fajph.92.8.1218">unusual number of cases of encephalitis</a> (inflammation of the brain). At the same time, the <a href="https://www.nationalgeographic.com/science/article/west-nile-virus-the-stranger-that-came-to-stay">Bronx Zoo</a> reported a massive death of birds and mammals. </p>
<p>The human encephalitis cases might have been attributed to a flare-up of an endemic arbovirus (<a href="https://ndc.services.cdc.gov/case-definitions/arboviral-diseases-neuroinvasive-and-non-neuroinvasive-2015/">a virus transmitted by a tick or mosquito bite</a>) such as <a href="https://www.cdc.gov/sle/index.html">St. Louis encephalitis</a>, but the concurrent bird and mammal deaths suggested the human illnesses warranted further investigation. </p>
<p>Scientists eventually identified these as the first confirmed cases of West Nile virus (WNV) in North America.</p>
<h2>West Nile virus in North America</h2>
<p>WNV was first reported in a woman with a fever in Uganda in 1937. An <a href="https://doi.org/10.2214/ajr.184.3.01840957">outbreak in Israel in 1957</a> established WNV as a cause of <a href="https://doi.org/10.3201/eid0704.017416">severe meningoencephalitis</a> (inflammation of the spinal cord and brain) in elderly patients. </p>
<p>Several clusters or medium-range outbreaks were reported from Asia, Europe and Africa in the 20th century. Finally, the virus managed to cross the Atlantic and landed in North America in 1999.</p>
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<img alt="Round blue particles nestled in a red matrix" src="https://images.theconversation.com/files/548213/original/file-20230914-19-x6rm98.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/548213/original/file-20230914-19-x6rm98.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=454&fit=crop&dpr=1 600w, https://images.theconversation.com/files/548213/original/file-20230914-19-x6rm98.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=454&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/548213/original/file-20230914-19-x6rm98.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=454&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/548213/original/file-20230914-19-x6rm98.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=570&fit=crop&dpr=1 754w, https://images.theconversation.com/files/548213/original/file-20230914-19-x6rm98.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=570&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/548213/original/file-20230914-19-x6rm98.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=570&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Microscopic view of West Nile virus particles in a cell.</span>
<span class="attribution"><span class="source">(NIAID)</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>In 1999, the <a href="https://www.cdc.gov/westnile/statsmaps/historic-data.html">case number</a> was limited to 62 in New York City, and there was concern about a huge surge in 2000. Fortunately, the case number in 2000 was 21, which is exceedingly low, but it had spread to New Jersey and Connecticut. The case number remained in a similar low range (only 66 cases) in 2001. </p>
<p>However, the virus hit hard the following year. In 2002, the case number rose to over 4,000 in the United States. The same year, <a href="https://www.canada.ca/en/public-health/services/diseases/west-nile-virus/surveillance-west-nile-virus.html">Canada experienced its first cases</a> in Ontario.</p>
<p>The U.S. has reported a <a href="https://www.cdc.gov/westnile/statsmaps/historic-data.html">cumulative total</a> of 56,569 cases and 2,773 deaths, while <a href="https://www.canada.ca/en/public-health/services/diseases/west-nile-virus/surveillance-west-nile-virus.html#a1">Canada has reported 6,683 cases</a> and about 150 deaths (I’m told by the Centre for Food-borne, Environmental & Zoonotic Infectious Diseases, Public Health Agency of Canada), with the highest number of cases observed in the U.S. in 2003 and in Canada in 2007.</p>
<p>This virus spread across the entire continent very quickly, and covered most of North America by 2005. However, it took almost 10 years for the virus to <a href="https://doi.org/10.1089/vbz.2010.0062">show up in British Columbia</a>. In Canada, most of the cases were found in the Prairie region (Alberta, Saskatchewan and Manitoba). <a href="https://www.cdc.gov/westnile/statsmaps/historic-data.html">In the U.S.</a>, Midwestern states have been most affected.</p>
<p>West Nile virus is an RNA virus, a close cousin of <a href="https://www.who.int/news-room/fact-sheets/detail/dengue-and-severe-dengue">Dengue</a>, <a href="http://www.bccdc.ca/health-info/diseases-conditions/yellow-fever">Yellow fever</a>, St. Louis encephalitis and <a href="http://www.bccdc.ca/health-info/diseases-conditions/zika-virus">Zika virus</a>, to name a few. It belongs to the family Flaviviridae. </p>
<h2>Symptoms and transmission</h2>
<p><a href="https://www.cdc.gov/westnile/symptoms/index.html">Approximately 80 per cent of people</a> exposed to WNV are asymptomatic. <a href="https://doi.org/10.14745/ccdr.v40i10a01">The incubation period</a> in humans is about a week; however, this ranges from two to 15 days after the virus enters the body.</p>
<p>Among symptomatic individuals, all of them experience fever, and many also experience headaches, body aches, a mild rash and swollen lymph glands to varying degrees. </p>
<p>Although most cases go unnoticed, the virus still has deadly potential. <a href="https://nccid.ca/debrief/west-nile-virus/">A small number of people</a> (around one per cent) experience severe symptoms, including encephalitis. However, over the years, the <a href="https://doi.org/10.1038/ncpneuro0176">number of neurological cases has been increasing</a>.</p>
<p>This virus is mostly <a href="https://www.who.int/news-room/fact-sheets/detail/west-nile-virus">transmitted via mosquito bites</a>; however, very rarely it could transmit via blood transfusion, organ or tissue transplants, from mother to unborn babies and through exposure to infected animals. </p>
<p>A number of birds, predominantly corvids such as crows, jays and magpies, act as reservoirs as well as <a href="https://www.biologyonline.com/dictionary/amplifier-host">amplifying hosts</a>. When an uninfected mosquito feeds on an infected bird and then bites a healthy human, the human becomes infected. </p>
<p>Humans are considered dead-end hosts, meaning that even if a mosquito feeds on an infected individual, that mosquito cannot transmit the virus to another individual <a href="https://www.who.int/news-room/questions-and-answers/item/dengue-and-severe-dengue">as can happen with the dengue virus</a>.</p>
<p>Once people are severely infected with West Nile virus, they <a href="https://www.cdc.gov/westnile/symptoms/index.html">acquire longer immunity</a>. Older people are usually at high risk for severe infection due to underlying health conditions. People with diabetes and uncontrolled hypertension <a href="https://www.canada.ca/en/public-health/services/diseases/west-nile-virus/risks-west-nile-virus.html">have a greater risk</a> of developing severe neurological disease from the West Nile virus. </p>
<h2>Diagnosis</h2>
<p>Patients who become ill with a fever and severe headache within a few days of a mosquito bite should visit their family physician or any health-care facility.</p>
<p>Because WNV is closely related to other pathogens, diagnosis is often challenging.
Patient signs and symptoms, history of mosquito bites and laboratory tests are all important when assessing patients for possible infection with West Nile virus.</p>
<p>The most common <a href="https://www.publichealthontario.ca/en/Laboratory-Services/Test-Information-Index/West-Nile-Virus-Serology">laboratory test</a> is to detect antibodies against WNV in the blood. However, WNV antibodies cross-react with dengue, Zika or other flaviviruses, so if this test is positive, an additional test is required to confirm the diagnosis. </p>
<p>This additional test is called the Plaque Reduction Neutralization Test or PRNT for short. It requires a live virus, so it must be done in a containment level 3 (CL3) laboratory. </p>
<p>The laboratory can also diagnose viral RNA using molecular tests, but interestingly, the virus often disappears from the blood when people exhibit symptoms. For encephalitic patients, cerebrospinal fluid can be used to detect the virus using molecular methods such as a polymerase chain reaction (PCR) test.</p>
<h2>Preventive measures</h2>
<p>There is no human vaccine for the West Nile virus. The most important preventive measure to avoid West Nile virus infection is to avoid mosquito bites. This seems simple but is often very challenging. </p>
<figure class="align-center ">
<img alt="Close-up view of a mosquito held with tweezers" src="https://images.theconversation.com/files/548224/original/file-20230914-17-vsdb54.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/548224/original/file-20230914-17-vsdb54.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/548224/original/file-20230914-17-vsdb54.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/548224/original/file-20230914-17-vsdb54.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/548224/original/file-20230914-17-vsdb54.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/548224/original/file-20230914-17-vsdb54.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/548224/original/file-20230914-17-vsdb54.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A Culex tarsalis mosquito, a species that can transmit West Nile virus to humans, and is found across Canada.</span>
<span class="attribution"><span class="source">(AP Photo/Rick Bowmer)</span></span>
</figcaption>
</figure>
<p>People should use common sense during outdoor and indoor activities. Mosquito bites can be prevented by using bug spray, wearing protective clothing and avoiding areas that may have mosquitoes during the times when the species is most active, typically dusk and dawn. </p>
<p>A few species of mosquitoes can transmit WNV to humans. Among these, two of the most common species — the Culex pipiens and Culex tarsalis — are found across Canada, and their habitat is <a href="https://ncceh.ca/resources/evidence-reviews/impacts-canadas-changing-climate-west-nile-virus-vectors">predicted to expand with climate change</a>. Mosquitoes not only transmit WNV, but also transmit <a href="https://www.canada.ca/en/public-health/services/laboratory-biosafety-biosecurity/pathogen-safety-data-sheets-risk-assessment/california-serogroup-pathogen-safety-data-sheet.html">California serogroup viruses</a>, which cause encephalitis, as well as <a href="https://www.canada.ca/en/public-health/services/laboratory-biosafety-biosecurity/pathogen-safety-data-sheets-risk-assessment/eastern-equine-encephalitis.html">eastern equine encephalitis</a> viruses. </p>
<p>There is also no specific treatment for West Nile virus; medical management is supportive. Patients with severe symptoms often require pain control for headaches and medication and rehydration to treat nausea and vomiting. </p>
<p><a href="https://www.canada.ca/en/public-health/services/diseases/west-nile-virus/surveillance-west-nile-virus/west-nile-virus-weekly-surveillance-monitoring.html">So far in 2023</a>, only a <a href="https://www.cbc.ca/news/canada/hamilton/hamilton-west-nile-virus-2023-1.6957260">few human cases</a> have been identified in Ontario. However, a few mosquito pools in Manitoba and Ontario also tested positive, and also a few WNV-positive birds were found in Saskatchewan, Manitoba, Ontario and Québec.</p>
<p>No matter how many cases we are seeing, everyone is advised to take precautions against mosquito bites to avoid these life-threatening diseases.</p><img src="https://counter.theconversation.com/content/212955/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Muhammad Morshed does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>West Nile virus arrived in North America in 1999 and spread across the continent by 2005. Here’s what you need to know about this mosquito-borne pathogen.Muhammad Morshed, Clinical Professor, Department of Pathology and Laboratory Medicine, University of British ColumbiaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1910332022-09-23T15:03:24Z2022-09-23T15:03:24ZDengue in France: tropical diseases in Europe may not be that rare for much longer<figure><img src="https://images.theconversation.com/files/486068/original/file-20220922-34615-sikp9n.jpg?ixlib=rb-1.1.0&rect=4%2C9%2C3282%2C2346&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/asian-tiger-mosquito-side-view-1264209730">Itsik Marom/Shutterstock</a></span></figcaption></figure><p>Dengue, a viral infection spread by mosquitoes, is a common disease in parts of Asia and Latin America. Recently, though, France has experienced an outbreak of <a href="https://www.connexionfrance.com/article/French-news/Health/France-warns-of-increased-risk-of-dengue-fever-from-tiger-mosquitoes">locally transmitted dengue</a>.</p>
<p>Dengue symptoms can include a fever, headache, joint pain, nausea and a red rash. Occasionally, though, it can lead to more severe disease – and even death.</p>
<p>Every year, France records a number of imported cases of dengue, where people have travelled to a country where dengue is endemic and brought the disease back with them. If a <a href="https://www.pasteur.fr/en/research-journal/news/tiger-mosquito-france-58-departements-red-alert">tiger mosquito</a> (<em>Aedes albopictus</em>) then bites the infected person, it can pass the infection on to someone who hasn’t travelled to an at-risk country. But it won’t transmit between people.</p>
<p>Since 2010, when local dengue transmission was first identified in France, there have been <a href="https://www.connexionfrance.com/article/French-news/Health/France-warns-of-increased-risk-of-dengue-fever-from-tiger-mosquitoes">around 12 cases a year</a>. However, since July 2022, there have been <a href="https://theconversation.com/les-cas-de-dengue-explosent-en-france-metropolitaine-que-faut-il-savoir-190729">nearly 40 cases</a> of locally transmitted dengue. And the French health authorities have warned of <a href="https://www.connexionfrance.com/article/French-news/Health/France-warns-of-increased-risk-of-dengue-fever-from-tiger-mosquitoes">more cases to come</a>. </p>
<p>One difficulty with controlling the spread of dengue is that the mosquitoes that spread it are active in the day and at night. The mosquitoes that spread malaria, on the other hand, are mainly active at night, so <a href="https://www.unicef.org/supply/stories/fighting-malaria-long-lasting-insecticidal-nets-llins">bed nets</a> are an effective way of reducing the risk of getting malaria in countries where the disease is endemic. But this control measure wouldn’t be as effective against dengue.</p>
<figure class="align-center ">
<img alt="Boy under a bed net" src="https://images.theconversation.com/files/486285/original/file-20220923-22-1bz36l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/486285/original/file-20220923-22-1bz36l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/486285/original/file-20220923-22-1bz36l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/486285/original/file-20220923-22-1bz36l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/486285/original/file-20220923-22-1bz36l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/486285/original/file-20220923-22-1bz36l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/486285/original/file-20220923-22-1bz36l.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">Bed nets are effective against malaria. Less so against dengue.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/little-african-boy-mosquito-net-protection-1812244213">Riccardo Mayer/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Climate change</h2>
<p>Mosquitoes spread many infectious diseases, including malaria, West Nile virus, yellow fever, Zika and chikungunya. These diseases are prevalent in areas that can be inhabited by mosquitoes. Habitats are often tropical areas across sub-Saharan Africa, South America or Asia. Transmission is via the mosquito bite, rather than person to person.</p>
<p>Climate change is having, and will continue to have, a significant effect on human and animal populations around the globe. Modelling has <a href="https://elifesciences.org/articles/55619">predicted</a> that changing temperature and rainfall across Africa could promote new habitats for mosquitoes to breed and, for example, increase yellow fever deaths by up to 25% by 2050. As a result, environmental risks are a <a href="https://www.who.int/initiatives/eye-strategy">core component</a> of the 2026 WHO Global Strategy to Eliminate Yellow Fever Epidemics. By 2030, the population at risk of <a href="https://malarianomore.org.uk/world-environment-day">malaria</a> in Africa will have increased by over 80 million, mainly as a result of climate change.</p>
<p>Mosquitoes cannot <a href="https://www.sciencedirect.com/science/article/pii/S0075951113001011">fly very far</a>, with distances ranging from a few metres to tens of kilometres. Imported cases of malaria or dengue are already common in returning travellers, but there is typically no local threat to the rest of the population. Despite this, the emerging threats from mosquito-driven diseases extend beyond the tropics. </p>
<p>Indeed, there have been over 570 cases of <a href="https://www.ecdc.europa.eu/en/publications-data/west-nile-virus-europe-2022-human-cases-updated-7-september-2022">West Nile virus</a> recorded in Europe this year. Most of these have been recorded in Veneto, in northern Italy. </p>
<p>It seems that the <a href="https://www.euronews.com/next/2022/08/11/cases-of-mosquito-borne-west-nile-fever-are-soaring-in-italy-this-is-what-you-need-to-know">lowlands</a> of Veneto are emerging as an ideal habitat for the <em>Culex</em> mosquitoes, which can host and transmit West Nile virus.</p>
<p>Globalisation and climate change have spurred the re-emergence of old diseases in new places. And public health authorities are taking these threats seriously. The <a href="https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/887925/National_contingency_plan_for_invasive_mosquitoes.pdf">UK Health Security Agency</a> has a national contingency plan for invasive mosquitoes. </p>
<p>As part of their fieldwork <a href="https://www.telegraph.co.uk/global-health/science-and-disease/why-official-mosquitoes-hunters-kent-fear-new-surge-malaria/">activity</a>, entomologists visit sites such as marshlands in the Thames Estuary in Kent. There, they catch mosquitoes and ticks and take them back to the laboratory for testing. This approach can help identify if the local insect populations are harbouring anything new, such as malaria or dengue, before it starts to spread.</p>
<h2>Vaccines</h2>
<p>The long-term future for the UK and other parts of Europe could require wider use of public health control measures, such as mosquito nets or insect sprays. Vaccine development is also likely to be critical as a preventive measure. </p>
<p>Yellow fever is already <a href="https://www.who.int/news-room/fact-sheets/detail/yellow-fever">vaccine-preventable</a>, and there are now licensed vaccines against <a href="https://www.un.org/africarenewal/magazine/july-2022/historic-funding-expand-roll-out-first-ever-malaria-vaccine-africa">malaria</a> being used in parts of sub-Saharan Africa. </p>
<p>Dengue vaccine candidates are <a href="https://www.cdc.gov/vaccines/vpd/dengue/public/index.html">emerging</a>, with one being licensed in the US. However, it comes with <a href="https://www.science.org/content/article/new-dengue-vaccine-should-only-be-used-people-who-were-previously-infected-who-says">recommendations</a> it should only be used in people who have already had dengue. This limits any widespread roll out.</p>
<p>There are huge numbers of people already at risk of mosquito-driven disease, and global inequities mean that poorer countries are <a href="https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(21)01787-6.pdf">most vulnerable</a> to climate change. The world needs to take seriously the threat of new diseases such as Zika, and neglected diseases, such as dengue. Populations at risk are only likely to increase over the coming years and decades.</p>
<p><em>Correction: An earlier version of this article stated that mosquitoes cause onchocerciasis (river blindness). This has been removed. Blackflies cause river blindness, not mosquitoes.</em></p><img src="https://counter.theconversation.com/content/191033/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Head has previously received funding from the Bill & Melinda Gates Foundation and the UK Department for International Development.</span></em></p>France experienced its largest outbreak of ‘native’ dengue this summer. Thanks to climate change, Europe can expect more of the same.Michael Head, Senior Research Fellow in Global Health, University of SouthamptonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1844122022-09-09T12:34:01Z2022-09-09T12:34:01ZLa Crosse virus is the second-most common virus in the US spread by mosquitoes – and can cause severe neurological damage in rare cases<figure><img src="https://images.theconversation.com/files/481864/original/file-20220830-19040-p60irc.jpg?ixlib=rb-1.1.0&rect=22%2C45%2C4998%2C3229&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">People catch La Crosse disease primarily from the bite of the eastern tree-hole mosquito – although two other species may also carry the virus.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/mosquito-sucking-blood-on-human-skin-royalty-free-image/1218518415?adppopup=true">Nipol Plobmuang/EyeEm via Getty Images</a></span></figcaption></figure><p>For the Laudick family of Greensburg, Indiana, life forever changed on Aug. 5, 2013. That was the day 4-year-old Leah Laudick told her mom, Shelly, that she had a bad headache. </p>
<p>Two days later, Leah was hospitalized nearby with worsening headaches and a slightly elevated white blood cell count. She slept for most of the day and by Aug. 9 was largely unresponsive. </p>
<p>That day, during her transfer to Peyton Manning Children’s Hospital in Indianapolis, Leah had her first of several seizures. Doctors were unable to identify her illness – tests for diseases like meningitis, Rocky Mountain spotted fever and herpes simplex all came back negative. </p>
<p>One day later, on Aug. 10, Leah’s brain activity stopped. That evening she passed away in the arms of her grieving parents. </p>
<p>A few months later, the Laudicks learned from the Centers for Disease Control and Prevention that an illness called La Crosse disease, contracted from the bite of a mosquito, had caused Leah’s death. </p>
<p>I am <a href="https://epp.tennessee.edu/directory/dr-rebecca-trout-fryxell/">an entomologist</a> at the University of Tennessee who studies how La Crosse disease spreads in the environment. I met the Laudicks – they have given me permission to tell their story – when Leah’s father, Andy, emailed me asking how he could help with my work. Such emails from parents of La Crosse-infected children are why I continue to study the virus. </p>
<p>Together with other <a href="https://www.mdpi.com/2075-4450/13/2/164">researchers at the University of Tennessee</a> and Western Carolina University, I’m working to provide people and communities with effective solutions to preventing this illness. Through my research and <a href="https://www.megabitess.org/">community engagement activities</a>, I am helping to increase awareness of what La Crosse virus is and how people catch it – and can avoid catching it. </p>
<h2>What is La Crosse disease?</h2>
<p><a href="https://www.cdc.gov/lac/index.html">La Crosse disease</a> is the nation’s <a href="https://doi.org/10.15585%2Fmmwr.mm7032a1">second-most prevalent mosquito-borne virus</a>. According to the CDC, West Nile virus makes up <a href="https://www.cdc.gov/mmwr/volumes/68/wr/mm6831a1.htm">more than 90% of annual viral infections</a> from mosquito or tick bites, with <a href="https://www.cdc.gov/mmwr/volumes/68/wr/mm6831a1.htm">La Crosse the next-most prevalent</a> at about 2% of mosquito or tickborne viral infections a year – <a href="https://www.cdc.gov/lac/statistics/index.html">or 50 to 150 cases a year</a>. Both children and adults can be infected with La Crosse virus.</p>
<p>La Crosse was first identified in the U.S. in 1960, and historically, most cases have occurred in <a href="https://doi.org/10.1371/journal.pone.0006145">Upper Midwest</a> and Mid-Atlantic states. Leah’s case was the only one reported in Indiana in 2013. </p>
<p>The majority now occur in the southern Appalachia region, which stretches from northern Alabama and Georgia, across eastern Tennessee and western North Carolina, and north to parts of Kentucky, Virginia and West Virginia. We still do not know why this is the case, but there are <a href="https://doi.org/10.1007/s10393-012-0773-7">many hypotheses</a> centered around climate, land use and invasive mosquito species.</p>
<p><iframe id="2m3d9" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/2m3d9/2/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<h2>How do people catch La Crosse?</h2>
<p>La Crosse virus is carried and transmitted primarily <a href="https://wrbu.si.edu/vectorspecies/mosquitoes/triseriatus">by the eastern tree-hole mosquito</a>, <em>Aedes triseriatus</em>, a native species found throughout most of the Eastern U.S. This mosquito’s preferred habitat is places with obvious tree holes <a href="https://wrbu.si.edu/vectorspecies/mosquitoes/triseriatus">for female mosquitoes to deposit their eggs</a>, such as hardwood forests.</p>
<p>However, the virus <a href="https://doi.org/10.2987/moco-31-03-233-241.1">may also be transmitted</a> – although not as well – by two exotic and invasive mosquito species: the <a href="https://www.wrbu.si.edu/vectorspecies/mosquitoes/albopictus">tiger mosquito</a>, <em>Aedes albopictus,</em> and <a href="https://www.wrbu.si.edu/index.php/vectorspecies/mosquitoes/japonicus">the bush mosquito</a>, <em>Aedes japonicus.</em></p>
<p>Tiger and bush mosquitoes are spreading throughout the U.S. in response to changes in landscape and climate, and also by hitchhiking inside water-filled containers. Our team has <a href="https://doi.org/10.1371/journal.pone.0237322">found them</a> together in the same habitats as eastern tree-hole mosquitoes, in places with hardwood trees like parks, cemeteries and residential backyards. Our team has also found these mosquitoes in <a href="https://doi.org/10.1371/journal.pone.0237322">close proximity</a> to confirmed La Crosse cases.</p>
<p>All three mosquito species develop in the same water sources and feed on mammals, including humans. Some <a href="https://doi.org/10.1007/s10393-012-0773-7">scientists speculate that</a> these factors have been key to the distribution of La Crosse in the Appalachian region, although there is still a lot to learn about these mosquito species and their role in spreading the virus.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/483611/original/file-20220908-9281-7nbj62.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Close-up photo of the eastern treehole mosquito." src="https://images.theconversation.com/files/483611/original/file-20220908-9281-7nbj62.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/483611/original/file-20220908-9281-7nbj62.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/483611/original/file-20220908-9281-7nbj62.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/483611/original/file-20220908-9281-7nbj62.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/483611/original/file-20220908-9281-7nbj62.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/483611/original/file-20220908-9281-7nbj62.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/483611/original/file-20220908-9281-7nbj62.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"></a>
<figcaption>
<span class="caption">The eastern tree-hole mosquito is the primary carrier of La Crosse virus.</span>
<span class="attribution"><span class="source">Dave Paulsen, Department of Entomology and Plant Pathology, University of Tennessee</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>Diagnosing La Crosse is difficult</h2>
<p>La Crosse disease is easy to misdiagnose, in part because its symptoms can be easily confused with those of other illnesses, such as the flu. Moreover, the only way to test for La Crosse involves <a href="https://www.cdc.gov/lac/healthcare-providers/diagnostic-testing.html">sending samples of blood and cerebrospinal fluid</a> to the CDC.</p>
<p>However, La Crosse infections <a href="https://doi.org/10.1371/journal.pone.0006954">tend to cluster in local communities</a> from year to year. For example, of the 115 cases reported in Tennessee since 2011, <a href="https://www.tn.gov/health/cedep/vector-borne-diseases/mosquito-borne-diseases/mosquito-borne-diseases-of-concern/la-crosse-encephalitis.html">most occurred in less than 20%</a> of the state’s 95 counties. So even a few successfully diagnosed cases can tip off local doctors and officials that the disease is present in their area. </p>
<h2>Symptoms of La Crosse</h2>
<p>Symptomatic cases of La Crosse begin with a mild illness involving fever, fatigue, vomiting and headache. This lasts for nearly two weeks. Most infected individuals recover fully.</p>
<p>However, like West Nile, La Crosse disease is “neuroinvasive,” meaning it can invade and affect the central nervous system.</p>
<p><a href="https://doi.org/10.1186/s12974-021-02173-4">Research suggests that age</a>, the <a href="https://doi.org/10.1186/s12974-017-0836-3">development of the immune system</a> and the <a href="https://doi.org/10.3201%2Feid2105.141992">strain of the virus</a> are key factors in whether someone develops neuroinvasive La Crosse, while delays in seeking medical help <a href="https://doi.org/10.1056/NEJM200103153441103">also influence its severity</a>. The most susceptible are immunocompromised individuals and children – more than 60 children a year are diagnosed with neuroinvasive La Crosse. </p>
<p>Severe cases <a href="https://doi.org/10.1542/hpeds.2012-0022">are usually discovered in the hospital</a> after the patient experiences a seizure, coma, partial paralysis of one side or altered mental state. </p>
<p>Severe La Crosse can result in <a href="https://doi.org/10.1093/cid/ciac403">long-term neurological damage</a>. Deaths caused by infection are rare, but neurological and behavioral effects can occur after infection, including cognitive disorders, diagnoses of attention-deficit/hyperactivity disorder and <a href="https://doi.org/10.1212/WNL.18.10.1023">reduced IQ scores</a>.</p>
<h2>Can La Crosse disease be prevented?</h2>
<p>Until the scientific community understands more about the ecology and epidemiology of La Crosse, my colleagues and I will continue to recommend preventing the mosquito bite in the first place to avoid infections.</p>
<p>One tactic is to reduce local opportunities for the mosquitoes that carry La Crosse to breed. This includes getting rid of objects outdoors that can catch and contain water – like empty plant pots, cans or toys – because these <a href="https://doi.org/10.52707/1081-1710-46.1.34">can emulate the conditions of a mosquito-friendly forest</a>. Mosquitoes carrying La Crosse virus are also found developing in tires containing water, so it’s a good idea <a href="https://doi.org/10.1093/jmedent/35.4.573">to drill drainage holes in tire swings</a>.</p>
<figure class="align-center ">
<img alt="Researcher crouching near the ground at sunny spot within a forest." src="https://images.theconversation.com/files/483330/original/file-20220907-9232-jgyaex.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/483330/original/file-20220907-9232-jgyaex.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=437&fit=crop&dpr=1 600w, https://images.theconversation.com/files/483330/original/file-20220907-9232-jgyaex.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=437&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/483330/original/file-20220907-9232-jgyaex.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=437&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/483330/original/file-20220907-9232-jgyaex.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=549&fit=crop&dpr=1 754w, https://images.theconversation.com/files/483330/original/file-20220907-9232-jgyaex.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=549&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/483330/original/file-20220907-9232-jgyaex.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=549&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Rebecca Trout Fryxell looks for mosquitoes in a puddle created by an above-ground tree root.</span>
<span class="attribution"><span class="source">Trout Fryxell’s Medical and Veterinary Entomology Laboratory, Univ. of Tennessee</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Another strategy is to try to avoid mosquitoes, perhaps by staying inside during peak mosquito hours, which are typically in the <a href="https://doi.org/10.2987/16-6620R.1">early evening</a>.</p>
<p>Using area repellents such as mosquito coils, wearing light-colored clothing and applying mosquito repellent can also help prevent bites. </p>
<p>The Environmental Protection Agency’s <a href="https://www.epa.gov/insect-repellents/find-repellent-right-you">guide to the active ingredients in insect repellents</a> describes which are most effective at repelling mosquitoes and how many hours they last. Like sunscreen, insect repellents may need to be reapplied while spending time outdoors. </p>
<p>Leah Laudick adored her six siblings and “enjoyed collecting rocks, chasing butterflies and picking flowers for her mom,” in the words of her father. </p>
<p>As officials and the public learn more about La Crosse, both avoiding and diagnosing the infection could become easier, and more lives like Leah’s could be saved.</p><img src="https://counter.theconversation.com/content/184412/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rebecca Trout Fryxell receives funding from the United States Department of Agriculture. </span></em></p>Not all cases of La Crosse disease affect the neurological system, but those that do can be severe and sometimes fatal – especially in children.Rebecca Trout Fryxell, Associate Professor of Medical and Veterinary Entomology, University of TennesseeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1888562022-08-18T14:11:44Z2022-08-18T14:11:44ZMosquitoes: there’s malaria, plus 5 other diseases they pass on to humans<figure><img src="https://images.theconversation.com/files/479588/original/file-20220817-16-p6zz3e.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">Tacio Philip Sansonovski/Shutterstock</span></span></figcaption></figure><p>Most people instantly associate mosquitoes with malaria. But these tiny flying insects can transmit a number of <a href="https://www.who.int/news-room/fact-sheets/detail/vector-borne-diseases">other diseases</a> too. </p>
<p>Viruses transmitted by insects like mosquitoes are called arthropod-borne or arboviruses. Like malaria, these viruses are transmitted to vertebrate hosts through the <a href="https://www.medicalnewstoday.com/articles/311485">bite of a female mosquito</a> when she takes a blood meal to assist with her egg development. Most vertebrate hosts for these arboviruses are non-human. They include birds, primates and agricultural animals. But some arboviruses can be transmitted to humans with severe negative outcomes. </p>
<p>Five of the most important arboviruses affecting communities in Africa include the chikungunya, dengue, West Nile, yellow fever and Zika viruses. It is <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8055094/">estimated</a> that half of the world’s population is at risk of being infected by an arbovirus.</p>
<p>Some mosquito-borne diseases – but not all – can be fatal to humans. This confirms that every effort must be made to prevent being bitten by a mosquito and infected using both pharmaceutical and non-pharmaceutical measures.</p>
<h2>Chikungunya</h2>
<p>The name chikungunya is derived from the Kimakonde language (used in Tanzania and Mozambique) and means “<a href="https://www.worldmosquitoprogram.org/sites/default/files/2022-04/WMP%20chikungunya%20%281%29.pdf">to become contorted</a>”. The symptoms of chikungunya virus include headaches, a rash, fatigue, fever and muscle and joint pain. Generally these symptoms clear within a week. Occasionally, an infection can result in a severe fever and extremely painful joints, which can last for months or years, inducing a hunched, contorted appearance. Unfortunately, there are no antiviral or vaccine treatments available for chikungunya virus. Deaths from chikungunya are rare and are generally associated with other underlying health problems.</p>
<p>The chikungunya virus was first identified in <a href="https://www.worldmosquitoprogram.org/en/learn/mosquito-borne-diseases/chikungunya">1952</a> during an outbreak in Tanzania. It is transmitted by <em>Aedes aegypti</em> and <em>Aedes albopictus</em> mosquitoes. Over 100 countries across the globe have reported chikungunya virus cases. The risk of outbreaks is extremely high wherever these mosquito species are present around homes and urban areas.</p>
<p>Female <em>Aedes</em> mosquitoes tend to feed just after sunrise and around sunset. They lay eggs that can survive drying out. This makes vector control rather challenging. Current control strategies focus on reducing the number of water containers that these mosquitoes like to breed in, the use of insecticides against adult mosquitoes and personal protection to prevent mosquito bites.</p>
<h2>Dengue</h2>
<p>The World Health Organization has classified <a href="https://www.worldmosquitoprogram.org/sites/default/files/2022-04/WMP%20dengue%20%281%29.pdf">dengue virus</a> as one of the top ten global health threats. It’s one of the fastest spreading mosquito-borne diseases. At least half of the world’s population is at risk of infection. </p>
<p>Like chikungunya virus, dengue is spread by <em>Aedes aegypti</em> and <em>Aedes albopictus</em> mosquitoes. Both viruses share the same control interventions and non-specific symptoms of headaches, a rash, fever and muscle and joint pain, so they are often misdiagnosed. </p>
<p>Most human cases of dengue are asymptomatic or present with mild symptoms, which last for two to seven days. In certain individuals, dengue virus progresses to severe disease and symptoms include persistent vomiting, bleeding gums or nose and enlarged liver. This must be treated as a medical emergency as these complications can be lethal. Dengue virus can be diagnosed using a rapid diagnostic test or a polymerase chain reaction (PCR) test. </p>
<p>But there is no treatment available. A vaccine has been developed and has been approved for use in a few countries – but is not widely available in <a href="https://www.who.int/news-room/fact-sheets/detail/dengue-and-severe-dengue">Africa at present</a>. </p>
<h2>Zika</h2>
<p>The Zika virus was identified in humans in the 1950s. But it only became a pathogen of major public concern in 2016 following the <a href="https://www.worldmosquitoprogram.org/en/learn/mosquito-borne-diseases/zika">2015 Zika virus pandemic</a>. The virus is transmitted by <em>Aedes aegypti</em> and <em>Aedes albopictus</em> mosquitoes, and is generally non-lethal in humans. Most people infected with Zika virus do not show any symptoms. A few have non-specific symptoms like fever, rash, headaches, muscle and joint pains and conjunctivitis. These can last two to seven days. </p>
<figure class="align-center ">
<img alt="parent and children working out in swimming pool" src="https://images.theconversation.com/files/479591/original/file-20220817-15-uou8bk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/479591/original/file-20220817-15-uou8bk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/479591/original/file-20220817-15-uou8bk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/479591/original/file-20220817-15-uou8bk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/479591/original/file-20220817-15-uou8bk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/479591/original/file-20220817-15-uou8bk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/479591/original/file-20220817-15-uou8bk.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 2015 Zika outbreak resulted in scores of babies born with microcephaly.</span>
<span class="attribution"><span class="source">Joa Souza/Shutterstock</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>Individuals infected with Zika virus while pregnant are at an <a href="https://www.who.int/news-room/fact-sheets/detail/zika-virus">increased risk</a> of stillbirth, abortion, neurological disorders or delivering children with birth defects, including microcephaly. PCR testing can be used to diagnose Zika virus, but there is no treatment available.</p>
<h2>Yellow fever</h2>
<p><em>Aedes aegypti</em> and <em>Aedes albopictus</em> mosquitoes are also responsible for the transmission of yellow fever, so named because the virus causes jaundice (yellowing of eyes and skin due to impaired liver function).</p>
<p>Symptoms in mild cases <a href="https://www.worldmosquitoprogram.org/en/learn/mosquito-borne-diseases/yellow-fever">include</a> fever, headaches, chills, back pain, fatigue, jaundice, vomiting and bleeding from the mouth, nose, eyes or stomach. These generally clear within five days. Approximately 50% of the small number of patients who develop severe symptoms will die with 10 days of becoming infected. Yellow fever can be diagnosed by PCR or enzyme-linked immunosorbent assay (ELISA). Although there is no treatment for yellow fever, a very effective vaccine is widely available. A single vaccine dose provides <a href="https://www.who.int/news-room/fact-sheets/detail/yellow-fever">lifelong immunity</a>, so all individuals living in or travelling to areas endemic for yellow fever should take the vaccine.</p>
<h2>West Nile</h2>
<p>The West Nile virus was first isolated from a woman in the <a href="https://www.who.int/news-room/fact-sheets/detail/west-nile-virus">West Nile region of Uganda</a>. It is transmitted by mosquitoes belonging the genus <em>Culex</em>. The natural vertebrate hosts are wild birds. But the virus can be transmitted to a number of different animals, including humans, through the bite of an infected mosquito. Approximately 80% of the people infected with West Nile virus will not show any symptoms. Those who do become symptomatic have mild non-specific symptoms that include headaches, fever, tiredness, body aches, nausea, vomiting and, occasionally, a rash. A small proportion of symptomatic patients, however, develop severe disease. This is associated with neurological impairment, and can be fatal in extreme cases. </p>
<p>West Nile virus infection can be diagnosed by PCR or ELISA, with only supportive treatment available for neurological impairment. It has been suggested that people who are older than 50 or immunocompromised are at greater risk of severe infection. An integrated approach comprising water management together with chemical and biological interventions is needed to control the spread of the <em>Culex</em> vectors.</p><img src="https://counter.theconversation.com/content/188856/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jaishree Raman receives funding from the Gates Foundation, the Global Fund, the South African Medical Research Council, the Research Trust, National Research Foundation and the National Institute for Communicable Diseases.</span></em></p><p class="fine-print"><em><span>Shüné Oliver receives funding from the National Research Foundation and the Female Academic Leadership Fellowship. </span></em></p>It is estimated that half of world’s population is at risk of being infected by an arbovirus.Jaishree Raman, Principal Medical Scientist and Head of Laboratory for Antimalarial Resistance Monitoring and Malaria Operational Research, National Institute for Communicable DiseasesShüné Oliver, Medical scientist, National Institute for Communicable DiseasesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1788882022-03-11T02:04:39Z2022-03-11T02:04:39ZDo I or my child need a Japanese encephalitis vaccine?<figure><img src="https://images.theconversation.com/files/451457/original/file-20220310-25-tb0t4h.jpg?ixlib=rb-1.1.0&rect=2%2C1%2C995%2C664&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/japanese-encephalitis-vaccine-glass-vial-1316315552">Shutterstock</a></span></figcaption></figure><p>This week we heard <a href="https://www.abc.net.au/news/2022-03-09/nsw-records-first-japanese-encephalitis-death/100896444">two Australians</a> have died from the mosquito-borne Japanese encephalitis virus. The virus has now been detected in four states.</p>
<p>Authorities are concerned we’ll see <a href="https://www.health.gov.au/news/japanese-encephalitis-virus-situation-declared-a-communicable-disease-incident-of-national-significance">more cases</a> around the country and have <a href="https://www.smh.com.au/politics/federal/thousands-of-vaccines-purchased-to-combat-encephalitis-with-2-billion-flu-and-covid-season-boost-20220310-p5a3k0.html">earmarked extra funding</a> to roll out vaccines to those at risk.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1502006612822999040"}"></div></p>
<p>Who is recommended to have the vaccine depends on factors including their age, occupation and location. Here’s what you need to know about accessing the vaccine in Australia, ahead of further announcements expected in coming days.</p>
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Read more:
<a href="https://theconversation.com/japanese-encephalitis-virus-has-been-detected-in-australian-pigs-can-mozzies-now-spread-it-to-humans-178017">Japanese encephalitis virus has been detected in Australian pigs. Can mozzies now spread it to humans?</a>
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<h2>What is Japanese encephalitis?</h2>
<p>Japanese encephalitis <a href="https://www.health.gov.au/health-topics/japanese-encephalitis#what-is-japanese-encephalitis">is caused by</a> the Japanese encephalitis virus. It spreads through mosquito bites. It cannot be transmitted from human to human.</p>
<p><a href="https://link.springer.com/article/10.1186/s40794-017-0057-x">Most people</a> will show no symptoms. However, 1% will develop swelling of the brain (encephalitis). Of those who have symptoms, up to 30% will die and a further 50% will have life-long neurological disability. The infection is particularly severe in the elderly or the young.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/451458/original/file-20220310-21-1lz7kz0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Japanese encephalitis virus" src="https://images.theconversation.com/files/451458/original/file-20220310-21-1lz7kz0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/451458/original/file-20220310-21-1lz7kz0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/451458/original/file-20220310-21-1lz7kz0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/451458/original/file-20220310-21-1lz7kz0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/451458/original/file-20220310-21-1lz7kz0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/451458/original/file-20220310-21-1lz7kz0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/451458/original/file-20220310-21-1lz7kz0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Japanese encephalitis virus is carried by mosquitoes.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/japanese-encephalitis-virus-3d-illustration-rna-556378159">Shutterstock</a></span>
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<p>The virus had previously been found in Southeast Asia, Western Pacific regions, and in the <a href="http://conditions.health.qld.gov.au/HealthCondition/condition/14/217/83/japanese-encephalitis">Torres Strait</a>.</p>
<p>However, because of its spread into new regions further south, last week Japanese encephalitis <a href="https://www.health.gov.au/news/japanese-encephalitis-virus-situation-declared-a-communicable-disease-incident-of-national-significance">was designated</a> a communicable disease of national significance.</p>
<h2>Tell me more about the vaccines</h2>
<p>Currently, <a href="https://www.nature.com/articles/s41541-021-00338-z#Tab1">seven Japanese encephalitis virus vaccines</a> are licensed for use in humans globally. Two of these – <a href="https://immunisationhandbook.health.gov.au/vaccine-preventable-diseases/japanese-encephalitis">Imojev and JEspect</a> – are approved for use in Australia by the Therapeutic Goods Administration.</p>
<p>Imojev is approved for those from nine months of age and is given as a single dose. JEspect is approved for use from two months of age and is given as two doses, 28 days apart. JEspect can be given to pregnant women, if necessary. </p>
<p>The level of immunity from these vaccines varies. A single dose of Imojev can provide immunity for <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3060383">up to five years</a>. Whereas JEspect requires two doses to provide immunity for <a href="https://www.sciencedirect.com/science/article/pii/S0264410X06013867?via%3Dihub">two years</a>, with <a href="https://www.sciencedirect.com/science/article/pii/S0264410X15006891?via%3Dihub">some studies</a> suggesting a third booster after 12 months provides longer protection.</p>
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<strong>
Read more:
<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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<hr>
<p>These vaccinations come with some side effects. These include redness, pain and mild swelling at the vaccination site. Other side effects include headache, fatigue and muscle pains.</p>
<p>These vaccines vary in the way they are prepared. Also, different strains of the virus are used to make the different vaccines. This can ultimately affect how well they work to prevent disease if there is a change in the current circulating virus strain.</p>
<h2>Who can get the vaccine?</h2>
<p>Vaccination is currently recommended for high-risk groups, which currently <a href="https://immunisationhandbook.health.gov.au/vaccine-preventable-diseases/japanese-encephalitis">includes</a>:</p>
<ul>
<li><p>laboratory workers who work with the virus</p></li>
<li><p>travellers who will spend one month or more in an endemic region </p></li>
<li><p>people living or working in the outer islands of the Torres Strait.</p></li>
</ul>
<p>Before the current spread of Japanese encephalitis you could get the vaccine at GP clinics specialising in travel medicine. It costs <a href="https://academic.oup.com/jtm/article-abstract/28/3/taaa232/6031799?redirectedFrom=fulltext">A$300-350</a>, which includes a GP visit and the vaccine itself.</p>
<p>But with the spread of the virus in mainland Australia, the definition of high risk will likely change and the vaccine may be available to those high-risk groups via their GP or at work. At this stage we don’t know if the vaccines would be free, but that will be confirmed in coming days.</p>
<p>For instance, <a href="https://www.abc.net.au/news/rural/2022-03-04/japanese-encephalitis-vaccine-rollout-targets-piggery-workers/100883414">piggery workers</a> are among workers expected to be considered high risk and be offered the vaccine.</p>
<p>That’s because Japanese encephalitis virus infects pigs (it has been detected in piggeries in NSW, Queensland, Victoria and South Australia). The virus then enters the mosquito population when they bite pigs, which then later bite humans and spread it to us.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1499664958967070725"}"></div></p>
<p>A <a href="https://www.health.gov.au/news/japanese-encephalitis-virus-situation-declared-a-communicable-disease-incident-of-national-significance">national group</a> of communicable disease, vaccine and virus experts is considering whether a wide vaccine rollout is needed and if so, how this might work.</p>
<p>National cabinet is also expected to discuss the issue and make further announcements shortly.</p>
<h2>How can I protect myself, even without the vaccine?</h2>
<p>There are currently no specific treatments for people with Japanese encephalitis. Symptoms are managed with supportive care, including fluids and pain relief. </p>
<p>Vaccination is one form of protection. However, the <a href="https://theconversation.com/how-to-mozzie-proof-your-property-after-a-flood-and-cut-your-risk-of-mosquito-borne-disease-178299">most useful protection</a> comes from not being bitten by a mosquito in the first place. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-best-and-worst-ways-to-beat-mosquito-bites-70274">The best (and worst) ways to beat mosquito bites</a>
</strong>
</em>
</p>
<hr>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-to-mozzie-proof-your-property-after-a-flood-and-cut-your-risk-of-mosquito-borne-disease-178299">How to mozzie-proof your property after a flood and cut your risk of mosquito-borne disease</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/178888/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lara Herrero receives funding from NHMRC for mosquito-transmitted viruses. </span></em></p><p class="fine-print"><em><span>Penny Rudd has received funding from the Qld government to repurpose drugs for mosquito borne viruses and currently receives funding from NHMRC for vaccine development towards viral diseases. </span></em></p>Until now, access to the vaccines has been limited. But that’s expected to change.Lara Herrero, Research Leader in Virology and Infectious Disease, Griffith UniversityPenny Rudd, Research Fellow, Institute for Glycomics, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1782992022-03-03T03:33:15Z2022-03-03T03:33:15ZHow to mozzie-proof your property after a flood and cut your risk of mosquito-borne disease<figure><img src="https://images.theconversation.com/files/449500/original/file-20220302-27-lbqti4.jpg?ixlib=rb-1.1.0&rect=54%2C186%2C5121%2C2359&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Cameron Webb/NSW Health Pathology</span>, <span class="license">Author provided</span></span></figcaption></figure><p>The <a href="https://www.abc.net.au/news/2022-03-02/more-wet-weather-to-come-as-east-coast-low-forms-off-nsw/100873942">extreme weather and flooding in recent days</a> is likely to boost mosquito numbers, even as we say goodbye to summer.</p>
<p>Like all insects, mosquitoes thrive in warm conditions. Water is also critical for the mosquito’s life cycle, as they lay eggs in and around water. More water generally means more mosquitoes. </p>
<p>Disease caused by mosquito-borne viruses can be potentially severe. These include: </p>
<ul>
<li><p><a href="https://theconversation.com/explainer-what-is-ross-river-virus-24630">Ross River</a> virus, which causes fever, chills, headache, muscle and joint pain and fatigue. It’s not fatal but it can be debilitating, and is the most commonly reported mosquito-borne disease in Australia </p></li>
<li><p><a href="https://www.health.nsw.gov.au/Infectious/factsheets/Pages/Barmah_Forest_virus_infection.aspx">Barmah Forest virus</a> is also common and causes fever, rash and sore joints</p></li>
<li><p>flaviviruses, including <a href="https://www.health.nsw.gov.au/Infectious/factsheets/Pages/kunjin_virus.aspx">West Nile (Kunjin)</a>, <a href="https://theconversation.com/explainer-what-is-murray-valley-encephalitis-virus-112212">Murray Valley encephalitis</a> and <a href="https://theconversation.com/japanese-encephalitis-virus-has-been-detected-in-australian-pigs-can-mozzies-now-spread-it-to-humans-178017">Japanese encephalitis</a> virus are extremely rare but can cause severe brain infection and death, in a small proportion of cases.</p></li>
</ul>
<p>Health authorities will be <a href="https://theconversation.com/the-worst-year-for-mosquitoes-ever-heres-how-we-find-out-68433">closely monitoring flood-affected regions</a> for these diseases.</p>
<p>While mosquito populations peak in summer, even without floods, these diseases <a href="https://bmcinfectdis.biomedcentral.com/articles/10.1186/s12879-020-05411-x">generally peak in March and April</a>. That’s because it takes time for the viruses to <a href="https://theconversation.com/how-australian-wildlife-spread-and-suppress-ross-river-virus-107267">spread by mosquitoes among the local wildlife</a>, such as water birds and native mammals, before spilling over into humans.</p>
<p>It’s too early to say what impact the floods will have on disease case numbers but it’s best to be prepared.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/la-nina-will-give-us-a-wet-summer-thats-great-weather-for-mozzies-147180">La Niña will give us a wet summer. That's great weather for mozzies</a>
</strong>
</em>
</p>
<hr>
<h2>What happened after previous floods?</h2>
<p>Major floods have triggered historically significant outbreaks of mosquito-borne disease in Australia. </p>
<p>Most notable was the outbreak of <a href="https://theconversation.com/explainer-what-is-murray-valley-encephalitis-virus-112212">Murray Valley encephalitis virus in the 1970s</a>. While authorities have been mindful of disease risk associated with flooding ever since, we’ve been spared a significant return of this virus.</p>
<p>Not so for Ross River virus. </p>
<p>In 2014-15, above average rainfall is thought to have provided habitat for freshwater mosquito populations that contributed to the major outbreak of Ross River virus in <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6874252/">northern NSW and southeastern Queensland</a>. </p>
<p>Flooding across Victoria over the 2016-2017 summer produced exceptional increases in mosquitoes. This resulted in the state’s largest outbreak of Ross River virus, with almost <a href="https://www.abc.net.au/news/2017-02-09/ross-river-virus-cases-spike-victoria-nsw/8255280">five times as many cases as the long-term average</a>. </p>
<p>Following the exceptional rainfall that broke the East coast bushfire-swept summer of 2019-2020, NSW experienced its <a href="https://www.phrp.com.au/issues/december-2020-volume-30-issue-4/bushfires-covid-19-and-mosquito-borne-disease/">biggest outbreak of Ross River virus on record</a>.</p>
<p>But more mosquitoes <a href="https://academic.oup.com/jme/article/51/6/1097/861519?login=true">don’t always mean more disease</a>. </p>
<p>Sometimes after floods, there is just too much water. It washes away any mosquito already present in the wetlands and displaces the animal hosts of viruses. </p>
<p>It may take some time for mosquitoes to move back in and build up their populations in the stagnant water left behind by the floods. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/drinking-water-can-be-a-dangerous-cocktail-for-people-in-flood-areas-178028">Drinking water can be a dangerous cocktail for people in flood areas</a>
</strong>
</em>
</p>
<hr>
<h2>What are health authorities on the look-out for?</h2>
<p>Extreme weather events, <a href="https://www.abc.net.au/news/2022-03-03/sydney-rain-to-continue-hundreds-evacuated/100877162">such as the record-breaking floods we’re currently seeing</a>, may cause more frequent and intense outbreaks of Ross River virus. </p>
<p>But it’s the potential to see the resurgence of more serious local mosquito-borne diseases – such as those caused by Murray Valley encephalitis virus – which has authorities most concerned because it causes more severe disease.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/is-climate-change-to-blame-for-outbreaks-of-mosquito-borne-disease-39176">Is climate change to blame for outbreaks of mosquito-borne disease?</a>
</strong>
</em>
</p>
<hr>
<p>The recent detection of <a href="https://theconversation.com/japanese-encephalitis-virus-has-been-detected-in-australian-pigs-can-mozzies-now-spread-it-to-humans-178017">Japanese encephalitis virus</a> for the first time in southeastern Australia has shocked many, even those who have studied mosquito-borne diseases for decades. The discovery has health authorities on alert given the seriousness of the disease this virus causes.</p>
<p>While La Niña has played a role in new disease emergence, that may also quickly change. If a return to El Niño-dominated weather patterns brings back drought, that would see those wildlife and mosquito populations disappear.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/449539/original/file-20220302-23-11oc00a.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/449539/original/file-20220302-23-11oc00a.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/449539/original/file-20220302-23-11oc00a.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/449539/original/file-20220302-23-11oc00a.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/449539/original/file-20220302-23-11oc00a.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/449539/original/file-20220302-23-11oc00a.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/449539/original/file-20220302-23-11oc00a.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Floodwaters can trigger the hatch of millions of mosquito larvae.</span>
<span class="attribution"><span class="source">Cameron Webb/NSW Health Pathology</span></span>
</figcaption>
</figure>
<h2>‘Mozzie proof’ your property and family as floodwaters recede</h2>
<p><a href="https://www.abc.net.au/news/2022-03-01/how-to-clean-up-after-brisbane-qld-nsw-weather-floods/100872504">Massive clean-ups will be required in coming weeks</a>. That means long hours outside and much work done to make homes safe and secure again.</p>
<p>There isn’t much you can do to stop mozzies flying into your backyard from nearby flooded bushland and wetland areas. </p>
<p>Insecticide spraying may provide some relief but it is a short-term fix. As many commonly used products are not specific to mosquitoes, <a href="https://theconversation.com/the-battle-against-bugs-its-time-to-end-chemical-warfare-111629">beneficial insects may also be killed</a> if not used with caution.</p>
<p>Repairing, replacing, or installing insect screens on windows and doors can provide a physical barrier to mosquitoes seeking to fly inside your home. </p>
<p>Mosquito nets can also be a quickly deployed protection measure.</p>
<p>In your backyard, clean up as much debris as is safe to do so. Water-holding containers will quickly become a home to mosquitoes. </p>
<p>Gutters, drains and rainwater tanks can also be home to mosquitoes, so clean out and screen where possible.</p>
<p>Mosquito repellent may be your best friend over coming weeks. There is a range of formulations available from your supermarket, pharmacy or camping store. Choose a product that contains <a href="https://theconversation.com/mozzies-biting-heres-how-to-choose-a-repellent-and-how-to-use-it-for-the-best-protection-150183">diethyltolumide, picaridin, or oil of lemon eucalyptus</a> as these products will provide the best protection. </p>
<p>To get the most out of your repellent, ensure you have an even coat on all exposed areas of skin.</p>
<p>There are some <a href="https://theconversation.com/insect-repellents-work-but-there-are-other-ways-to-beat-mosquitoes-without-getting-sticky-171805">alternatives to topical insect repellents</a>, such as mosquito coils and other devices, but they can be limited in the protection provided. </p>
<p>Insecticide-treated clothing <a href="https://theconversation.com/mozzie-repellent-clothing-might-stop-some-bites-but-youll-still-need-a-cream-or-spray-107266">may also assist</a> in beating the bites.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/insect-repellents-work-but-there-are-other-ways-to-beat-mosquitoes-without-getting-sticky-171805">Insect repellents work – but there are other ways to beat mosquitoes without getting sticky</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/178299/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>Mosquitoes love water and with floodwater set to remain for some time, expect mosquito numbers to increase. Here’s how to avoid mozzie bites and the diseases they bring.Cameron Webb, Clinical Associate Professor and Principal Hospital Scientist, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1764232022-02-24T12:29:27Z2022-02-24T12:29:27ZMosquitoes might be attracted to certain colours – new research<figure><img src="https://images.theconversation.com/files/447870/original/file-20220222-21-1b70qhq.jpg?ixlib=rb-1.1.0&rect=11%2C0%2C7337%2C4880&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/hard-difficult-tiring-exhausting-expedition-four-683551939">Roman Samborskyi/Shutterstock</a></span></figcaption></figure><p>There’s no question that finding yourself covered in mosquito bites quickly takes the shine off a pleasant summer evening. But mosquitoes are more than a nuisance. They’re also the <a href="https://pubmed.ncbi.nlm.nih.gov/32191853/">deadliest creatures</a> on Earth, owing to <a href="https://www.who.int/news-room/fact-sheets/detail/vector-borne-diseases">the diseases</a> they spread.</p>
<p>A lot of research on mosquitoes is dedicated to <a href="https://pubmed.ncbi.nlm.nih.gov/23020619/">understanding their behaviour</a> and preferences for who they bite. Vision is an important sense in biting insects, including mosquitoes. Although they don’t rely on <a href="https://www.cabi.org/isc/abstract/19990505183">their vision</a> alone – smell and temperature work with visual cues to <a href="https://www.sciencedirect.com/science/article/pii/S096098221500891X">help mosquitoes</a> locate a host.</p>
<p>Previous research has <a href="https://academic.oup.com/jme/article-abstract/29/2/278/2221060?login=false">sought to link</a> particular colours (or the wavelengths of light which we see as distinct colours) to mosquitoes’ <a href="https://www.researchgate.net/profile/Lynda-Perkins/publication/21531025_Aedes_aegypti_Diptera_Culicidae_Vision_Response_to_Stimuli_from_the_Optical_Environment/links/5b03b0c50f7e9be94bdadcdd/Aedes-aegypti-Diptera-Culicidae-Vision-Response-to-Stimuli-from-the-Optical-Environment.pdf">host-seeking behaviour</a>. However, the results have been mixed, with the same mosquito species showing preferences for different colours in different studies.</p>
<p>A <a href="https://www.nature.com/articles/s41467-022-28195-x">recent study</a> published in the journal Nature Communications is the latest to explore mosquitoes’ attraction to different colours. Could this research tell us how to avoid being bitten simply by adjusting the colours we wear? Let’s take a look.</p>
<p>The researchers conducted a series of experiments on three disease-spreading mosquito species: primarily <em>Aedes aegypti</em>, but also <em>Anopheles stephensi</em> and <em>Culex quinquefasciatus</em>. </p>
<p>In one experiment they used a wind tunnel equipped with cameras to track the mosquitoes’ flight patterns. The tunnel was designed to encourage them to behave as naturally as possible.</p>
<p>On the floor of the tunnel were two small coloured spots; one to represent the colour (wavelength) of interest and a control (white). Some of the colour samples were chosen to mimic different skin tones, including one to represent the colour of tanning lotion.</p>
<p>In mosquitoes, only the <a href="https://link.springer.com/book/10.1007/978-3-540-92874-4">females bite</a>, because in most species they require a blood meal to complete the reproductive process. So 50 mated but unfed female mosquitoes were released into the wind tunnel, where they would naturally search for a host. </p>
<p>After an hour carbon dioxide (CO₂) was released into the wind tunnel. CO₂ is exhaled by humans and other mammals. While it’s odourless to us, mosquitoes can smell it and use this scent to help guide them to a source of blood.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-what-would-happen-if-all-the-mosquitoes-in-the-world-disappeared-175528">Curious Kids: What would happen if all the mosquitoes in the world disappeared?</a>
</strong>
</em>
</p>
<hr>
<h2>Seeing red</h2>
<p>Before the odour stimulus was released, the <em>Ae. aegypti</em> mosquitoes largely ignored the coloured circles on the floor, instead exploring the ceiling and the walls of the tunnel. But once CO₂ had been introduced they started to investigate the coloured circles, particularly as the wavelength increased from 510 nanometres (nm) to 660nm. </p>
<p>These longer wavelengths represent colours in the orange and red end of the spectrum, though the <em>Ae. aegypti</em> mosquitoes were most attracted to the red, and then black. Notably, these orange to red wavelengths are the same as those given off from human skin tones. Blue, green and violet weren’t any more attractive to the mosquitoes than the control.</p>
<p>When the skin tone spots were used, they were more attractive to the mosquitoes than the control, but no preference was observed for any particular skin tone.</p>
<figure class="align-center ">
<img alt="A mosquito on skin." src="https://images.theconversation.com/files/447875/original/file-20220222-13-ie6n1z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/447875/original/file-20220222-13-ie6n1z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/447875/original/file-20220222-13-ie6n1z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/447875/original/file-20220222-13-ie6n1z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/447875/original/file-20220222-13-ie6n1z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/447875/original/file-20220222-13-ie6n1z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/447875/original/file-20220222-13-ie6n1z.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">The researchers wanted to explore the role of colours in attracting mosquitoes.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/dangerous-malaria-infected-mosquito-skin-bite-1483138139">nechaevkon/Shutterstock</a></span>
</figcaption>
</figure>
<p><a href="https://www.sciencedirect.com/science/article/pii/S096098221500740X">Previous experiments</a> have shown mosquitoes are more attracted to contrasting colours, like a chequerboard pattern, than one solid colour. The researchers also showed the mosquitoes different spots against both similar and contrasting backgrounds. <em>Ae. aegypti</em> were more interested in spots with a high contrast to the background. Scientists believe this helps the mosquitoes distinguish between an object (person) and the background, even in low light. The contrast was more important in attracting the mosquitoes than the colour itself.</p>
<p>Similar to <em>Ae. aegypti</em>, <em>An. stephensi</em> were attracted to black and red, with little interest in the lower wavelengths. <em>Cx. quinquefasciatus</em> showed interest in violet/blue and red (interestingly, opposite ends of the tested spectrum).</p>
<p>The researchers conducted a separate experiment in insect cages to explore the mosquitoes’ attraction to real skin tones. Six volunteers from different ethnic backgrounds were recruited to help with this test. The control was a white glove in one window and the volunteers’ hands were held one at a time in the other window to see if the mosquitoes were attracted to any particular skin tone. </p>
<p>The mosquitoes were more attracted to the hands than the white glove, but as with the dots, there wasn’t a preference for a particular skin tone. </p>
<h2>What does this all mean?</h2>
<p>This study shows that mosquitoes are attracted to the colours found in human skin, but only in the presence of CO₂, suggesting the smell of human or mammal respiration may act as the initial cue. This confirms <a href="https://pubmed.ncbi.nlm.nih.gov/24315103/">previous research</a> which has found CO₂ attracts mosquitoes.</p>
<p>The researchers found that colour and contrast were important factors for <em>Ae. aegypti</em> who showed a preference for red, then black. <em>An. Stephensi</em> were interested in colours similar to <em>Ae aegypti</em>, though preferring black over red. Meanwhile, <em>Cx. quinquefasciatus</em> were interested in a range of colours. </p>
<p>As the researchers recognised, their experiments didn’t account for some of the <a href="https://pubmed.ncbi.nlm.nih.gov/23020619/">other factors</a> that affect mosquitoes’ choice of host. These include chemicals released from human skin, the temperature of the skin, and sweat on the skin. It would be interesting for future experiments to include these factors. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-mosquitoes-bite-some-people-more-than-others-101353">Why mosquitoes bite some people more than others</a>
</strong>
</em>
</p>
<hr>
<p>So what does this mean for the average person who doesn’t want to get bitten? You could try wearing white, blue or green and avoiding black, red and orange. Definitely avoid red and black checked patterns. </p>
<p>While adjusting your clothing may reduce your risk of being bitten, there’s no guarantee it will, or how effective this will be, particularly given the apparent variation in colour preferences between species. But these findings do suggest that with more research, colour could potentially be used as a tool in mosquito control.</p><img src="https://counter.theconversation.com/content/176423/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cassandra Edmunds 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>Could this study provide an insight into how to avoid being bitten simply by adjusting the colours we wear? Let’s take a look.Cassandra Edmunds, Lecturer in Forensic Biology, Bournemouth UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1718052022-01-31T05:39:31Z2022-01-31T05:39:31ZInsect repellents work – but there are other ways to beat mosquitoes without getting sticky<figure><img src="https://images.theconversation.com/files/443310/original/file-20220131-15248-1b08evd.jpg?ixlib=rb-1.1.0&rect=8%2C0%2C5982%2C3997&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/dad-son-use-mosquito-spray-insect-1081091330">Shutterstock</a></span></figcaption></figure><p>Summer can be hot and sticky. And insect repellent creams, lotions, and sprays can make it stickier. </p>
<p>Stopping mosquito bites is key to avoiding itchy bumps and mosquito-borne disease. Thankfully, there are several methods can you try – and some things to avoid – for a mozzie bite-free summer.</p>
<h2>Topical insect repellents are safe and effective</h2>
<p>Insect repellents are a safe, effective, and affordable way to <a href="https://www.phrp.com.au/issues/december-2016-volume-26-issue-5/a-review-of-recommendations-on-the-safe-and-effective-use-of-topical-mosquito-repellents/">prevent mosquito bites</a>. </p>
<p>They are <a href="https://www.frontiersin.org/articles/10.3389/fpubh.2019.00054/full">promoted by health authorities in Australia</a> as the best way to avoid mosquito bites.</p>
<p>Products sold in Australia must be approved for sale by the <a href="https://apvma.gov.au/">Australian Pesticides and Veterinary Medicines Authority</a> (APVMA) which checks products for safety and effectiveness. If applied as recommended – a thin and even coat over all exposed areas of skin – insect repellents can prevent mosquito bites. How long bite protection lasts varies with the strength of the formulation but research has shown it can <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1753-6405.2009.00435.x">last for many hours</a>.</p>
<p>But insect repellents aren’t always the perfect solution. Despite being <a href="https://academic.oup.com/jtm/article/17/3/182/1804104?login=true">recommended by health authorities and experts</a> around the world and many studies demonstrating registered repellents cause <a href="https://www.sciencedirect.com/science/article/pii/S1080603215004342">minimal adverse reactions</a>, there remains a perception they can pose a <a href="https://www.health.harvard.edu/blog/be-vigilant-about-bug-spray-2020080720702">health risk</a>, <a href="https://pubmed.ncbi.nlm.nih.gov/28171823/">contaminate</a> the natural environment or they’re unpleasant to use.</p>
<p>In Australia, not much has changed with regard to the active ingredients used in repellent formulations but the cosmetic constituents have greatly improved, making them more pleasant to use. </p>
<p>For those who find insect repellents a challenge, there are alternatives to creams, lotions and sprays. </p>
<h2>Insecticide sprays ✅</h2>
<p>Insecticides can help <a href="https://academic.oup.com/ee/article/49/2/435/5709893?login=true">knock down or repel</a> buzzing and biting mosquitoes. But, be warned, these products aren’t specific to mosquitoes so using them too frequently will <a href="https://theconversation.com/the-battle-against-bugs-its-time-to-end-chemical-warfare-111629">reduce the beneficial insects</a> around your home.</p>
<h2>Mosquito coils and other devices ✅</h2>
<p>Mosquito coils have been a mainstay of the Australian summer. They will certainly <a href="https://bioone.org/journals/Journal-of-the-American-Mosquito-Control-Association/volume-22/issue-1/8756-971X(2006)22%5B158:FEONMS%5D2.0.CO;2/FIELD-EVALUATION-OF-NEW-MOUNTAIN-SANDALWOOD-MOSQUITO-STICKSsup-supAND-NEW/10.2987/8756-971X(2006)22%5B158:FEONMS%5D2.0.CO;2.short">assist in reducing bites</a> in sheltered areas and those with insecticides will work best. </p>
<p>But never burn them inside, especially not beside the bed at night. The smoke you inhale <a href="https://theconversation.com/are-mosquito-coils-good-or-bad-for-our-health-88548">can be bad for your health</a>.</p>
<p>A range of <a href="https://parasitesandvectors.biomedcentral.com/articles/10.1186/1756-3305-5-287">alternative devices</a> work like “smoke free” mosquito coils. These devices are either battery or plug in powered and rely on heating an insecticide treated pad or reservoir of oil to release product that knocks out or repels mosquitoes. These can be a useful option indoors and can even be paired with a timer to work for only a few hours during the evening.</p>
<p>Portable devices are that can be clipped to your belt when out and about. It’s important to remember that as soon as you’re outside, especially in windy conditions or close to wetland or bushland areas, these products become less effective. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/443312/original/file-20220131-19-1ntd0v3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="mosquito coil" src="https://images.theconversation.com/files/443312/original/file-20220131-19-1ntd0v3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/443312/original/file-20220131-19-1ntd0v3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/443312/original/file-20220131-19-1ntd0v3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/443312/original/file-20220131-19-1ntd0v3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/443312/original/file-20220131-19-1ntd0v3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/443312/original/file-20220131-19-1ntd0v3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/443312/original/file-20220131-19-1ntd0v3.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">Never use smoking coils inside.</span>
<span class="attribution"><a class="source" href="https://image.shutterstock.com/image-photo/mosquito-repellent-600w-626047901.jpg">Shutterstock</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-when-we-get-bitten-by-a-mosquito-why-does-it-itch-so-much-93347">Curious Kids: When we get bitten by a mosquito, why does it itch so much?</a>
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<hr>
<h2>Dress for success ✅</h2>
<p>Probably the best alternative to putting repellents on your skin is to cover up. This is always tricky when it is hot and humid but the physical barrier clothing provides may be the best option in areas where mosquito activity is high.</p>
<p>Long sleeved shirts, long pants, and covered shoes are <a href="https://www.health.nsw.gov.au/Infectious/factsheets/Pages/mosquito.aspx">key</a> to this approach. </p>
<p>Protection against mosquito bites can be improved by <a href="https://theconversation.com/mozzie-repellent-clothing-might-stop-some-bites-but-youll-still-need-a-cream-or-spray-107266">applying an insecticide to clothing</a>. For <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0152805">extra protection</a>, clothing can be treated with the insecticide permethrin – the same insecticide used to treat bed nets in countries prone to malaria. Always use as directed and do not apply directly to the skin.</p>
<h2>Wrist bands and sound emitting devices ❌</h2>
<p>For those wanting to avoid topical repellents, the coloured wrist bands sold in many pharmacies and supermarkets may seem an desirable option. Unfortunately, there is <a href="https://search.informit.org/doi/abs/10.3316/INFORMIT.227605874334644">no scientific evidence</a> these devices, irrespective of the active ingredients they contain, can provide whole body protection against mosquitoes.</p>
<p>Mosquitoes don’t seem put off by sound either. For decades small sound-emitting devices have been sold, and <a href="https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD005434.pub2/full">repeatedly shown to be ineffective</a>. “Mosquito repellent” smart phone apps <a href="https://theconversation.com/the-buzz-from-your-smartphone-wont-stop-mosquito-bites-92611">don’t work either</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/439998/original/file-20220110-23-13op6fi.jpg?ixlib=rb-1.1.0&rect=36%2C72%2C3989%2C2921&q=45&auto=format&w=1000&fit=clip"><img alt="girl runs in sprinkler outside" src="https://images.theconversation.com/files/439998/original/file-20220110-23-13op6fi.jpg?ixlib=rb-1.1.0&rect=36%2C72%2C3989%2C2921&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/439998/original/file-20220110-23-13op6fi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/439998/original/file-20220110-23-13op6fi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/439998/original/file-20220110-23-13op6fi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/439998/original/file-20220110-23-13op6fi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/439998/original/file-20220110-23-13op6fi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/439998/original/file-20220110-23-13op6fi.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">Summer fun is quickly ruined by mosquito bites.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/FRsGNnM4Z18">Elena Rabkina/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Changing your diet ❌</h2>
<p>It would be wonderful if there was a pill we could take to prevent us being bitten by mosquitoes. It would overcome the challenges of getting you to apply sticky and unusual smelling solutions throughout summer. Problem is, such a thing doesn’t exist. There is <a href="https://theconversation.com/what-can-i-eat-to-stop-mosquitoes-biting-me-87178">no scientific evidence</a> anything you can eat or drink will prevent mosquitoes biting you.</p>
<p>You can still enjoy your gin and tonic, bananas, or vegemite on toast – just don’t expect the mosquitoes to stop biting!</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/bzzz-slap-how-to-treat-insect-bites-home-remedies-included-148722">Bzzz, slap! How to treat insect bites (home remedies included)</a>
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</em>
</p>
<hr>
<h2>The final word (give repellents a chance)</h2>
<p>It is important to remember mosquitoes are <a href="https://theconversation.com/how-can-the-bite-of-a-backyard-mozzie-in-australia-make-you-sick-171601">more than just a nuisance</a>. Viruses spread by mosquitoes in Australia can cause debilitating disease. There are few treatments available for these illnesses, so prevention is vital.</p>
<p>You may not like applying insect repellent, but it is probably the best strategy we’ve got. Just as we’ve developed the habit of using sunscreen on a regular basis, we need to get into the swing of smearing or spraying on some insect repellent during the warmer months too.</p><img src="https://counter.theconversation.com/content/171805/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>Summer is no fun when mosquitoes are biting. Insect repellent creams, sprays, and lotions are safe and effective but there are alternatives. Here’s what works and what doesn’t!Cameron Webb, Clinical Associate Professor and Principal Hospital Scientist, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1747972022-01-13T15:25:26Z2022-01-13T15:25:26ZWe studied the sounds of mosquitoes’ mating rituals – our findings could help fight malaria<figure><img src="https://images.theconversation.com/files/440695/original/file-20220113-15-1sshzwi.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3235%2C2158&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/two-mosquitos-on-human-skin-sunset-257567473">mycteria/Shutterstock</a></span></figcaption></figure><p>In 2020, the <a href="https://www.who.int/news-room/fact-sheets/detail/malaria">World Health Organization</a> (WHO) estimated that almost half the world’s population was at risk of malaria, while some 627,000 people died from the disease. </p>
<p>Although a malaria vaccine may soon be available (the WHO <a href="https://www.who.int/news/item/06-10-2021-who-recommends-groundbreaking-malaria-vaccine-for-children-at-risk">recommended</a> one for children last year), malaria is just one of several mosquito-borne diseases. And the total number of mosquito-related infections is <a href="https://www.nature.com/articles/s41564-019-0376-y">bound to rise</a> as climate change extends mosquito populations. So, to reduce the burden of disease from malaria and other mosquito-borne illnesses, we need to continue to develop effective tools to control mosquito populations.</p>
<p>A prime target is their mid-air copulation. Mosquitoes’ mating ritual involves a male identifying and pursuing a flying female by detecting her faint flight tone. If the male can’t properly hear the female, then the chase fails and they don’t mate. Reproduction in mosquitoes crucially relies on their sense of hearing.</p>
<p>We studied the behaviour of mosquitoes that cause malaria (the <em>Anopheles gambiae</em> species) to understand more about how males listen out for females to secure a mate. Our results have recently been published in the journal <a href="https://www.science.org/doi/10.1126/sciadv.abl4844">Science Advances</a>.</p>
<p>But first, a bit of background. The mechanism of hearing in mosquitoes is unique, yet poorly understood. The ears of both sexes are near-deaf to each other’s flight sounds, the frequencies of which are simply too high to be audible. To hear each other, they borrow a trick from physics. </p>
<p>When male and female flight tones combine in a mosquito ear, they create lower-frequency – and therefore audible – “phantom tones”, called <a href="https://aip.scitation.org/doi/pdf/10.1063/1.3658134">distortion products</a>. Distortion products only exist inside the mosquito ear and cannot be heard, or recorded, outside of it.</p>
<p>A male mosquito therefore needs to fly to hear a flying female. And his own flight tone needs to be within a specific frequency range to generate audible distortion products with a given female.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/new-malaria-vaccine-proves-highly-effective-and-covid-shows-how-quickly-it-could-be-deployed-159585">New malaria vaccine proves highly effective – and COVID shows how quickly it could be deployed</a>
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</em>
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<hr>
<h2>We listened to mozzies’ flight tones</h2>
<p>We recorded the flight tones (or “wing beats”) of mosquitoes in incubators fitted with highly sensitive microphones. Our experiments included looking at 100 males and 100 females in separate incubators, individual mosquitoes (one male or one female, separately), as well as a mixed incubator, with 50 mosquitoes of each sex.</p>
<p>In the incubators, we sought to emulate the conditions of their natural environment with lighting, and by controlling temperature and humidity. We were able to measure the frequency of the mosquitoes’ wing beats across several days and at different times of the day.</p>
<p>We found that male mosquitoes, but not females, altered their flight tones in a daily pattern. By beating their wings roughly 1.5 times faster than the females do, males optimise their ability to detect a single female within crowded swarms.</p>
<p>More than a decade ago, scientists proposed and described an acoustic interaction between males and females as “<a href="https://www.science.org/doi/10.1126/science.1166541">harmonic convergence</a>”. While they identified the same ratio of wing beats that allow mosquitoes of the opposite sex to hear each other (the equivalent of 1.5 male wing beats to one female wing beat), we found that this happens by default and doesn’t actually require any interaction between the sexes. </p>
<figure class="align-center ">
<img alt="A swarm of mosquitoes over water." src="https://images.theconversation.com/files/440698/original/file-20220113-23-1lxv9wt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/440698/original/file-20220113-23-1lxv9wt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=320&fit=crop&dpr=1 600w, https://images.theconversation.com/files/440698/original/file-20220113-23-1lxv9wt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=320&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/440698/original/file-20220113-23-1lxv9wt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=320&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/440698/original/file-20220113-23-1lxv9wt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=402&fit=crop&dpr=1 754w, https://images.theconversation.com/files/440698/original/file-20220113-23-1lxv9wt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=402&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/440698/original/file-20220113-23-1lxv9wt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=402&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Mosquitoes tend to swarm at dusk, and this is when mating occurs.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/swarm-mosquitoes-near-reeds-on-pond-627324473">VladKK/Shutterstock</a></span>
</figcaption>
</figure>
<p>Notably, we found the males beat their wings faster at dusk than at other times of the day. This makes sense because in <em><a href="https://onlinelibrary.wiley.com/doi/10.1111/j.1365-3032.1979.tb00185.x">Anopheles gambiae</a></em> mosquitoes, males predominantly fly around dusk when they form mating swarms, often of 1,000 mosquitoes or more. These swarms are sporadically visited by a few virgin females. As you can imagine, finding a mating partner is not easy.</p>
<p>The males’ increase in wing-beat frequency at dusk changes the frequency of the distortion products, which become more audible to the male ear than those created at other times of the day. So by adjusting their wing beat in the swarm, they’re better able to hear females and increase their chances of finding one to mate with.</p>
<p>The males’ flight tone adjustment is partly driven by their circadian clocks. Flapping their wings faster is likely to be very energy intensive for the males, so they restrict this behaviour to the time of swarming.</p>
<h2>What do our findings mean?</h2>
<p>It will be important to replicate similar experiments outside the lab, specifically among mosquito swarms in their natural habitat. We’ve already begun working on this in Tanzania.</p>
<p>Still, these findings open new avenues for research into the evolutionary ecology of hearing, the unique hearing system in mosquitoes, and mosquito behaviour more broadly.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/mosquito-bites-widely-available-skin-cream-found-to-prevent-the-spread-of-deadly-viruses-new-research-130246">Mosquito bites: widely available skin cream found to prevent the spread of deadly viruses – new research</a>
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</p>
<hr>
<p>They could also contribute to mosquito control efforts. As part of <a href="https://www.nature.com/articles/d41586-020-02492-1">vector control programmes</a>, mutant males will be released into the wild to collapse local mosquito populations. Mutant male mosquitoes are <a href="https://theconversation.com/using-gene-drives-to-control-wild-mosquito-populations-and-wipe-out-malaria-104613">genetically modified</a> so that when they mate with a female, the offspring isn’t viable and will die. </p>
<p>Mating efficiency in this context relies heavily on the released males’ ability to hear the “resident” females. Our results suggest that to create a successful programme, it may be important to assess male and female flight tone distributions, alongside male hearing ranges, before releasing the mutant mosquitoes. </p>
<p>This would strengthen any intervention by ensuring that the mutants’ mating efficiency is optimal – essentially that they can compete with the resident male mosquitoes to identify and mate with the resident females.</p><img src="https://counter.theconversation.com/content/174797/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Joerg T Albert received funding from the European Research Council (ERC) under the Horizon 2020 research and innovation programme (grant agreement no. 648709) and through a pump-priming award from the Biotechnology and Biological Sciences Research Council (BBSRC) Vector Borne Disease (VBD) Network ANTI-VeC (AV/PP/0028/1), a UCL Global Challenges Research Fund (GCRF) small grant, a BBSRC responsive mode grant (BB/V007866/1) and a Programme Grant from the Human Frontier Science Programme (RGP0033/2021). He is affiliated with the Francis Crick Institute (London, UK).</span></em></p><p class="fine-print"><em><span>Alex Alampounti is affiliated with the Francis-Crick Institute (London,UK). </span></em></p><p class="fine-print"><em><span>Marcos Georgiades is affiliated with the Francis Crick Institute (London, UK). </span></em></p>Reproduction in mosquitoes crucially relies on their sense of hearing.Joerg T Albert, Professor of Sensory Biology & Biophysics, UCLAlex Alampounti, Research Fellow, Biophysics, UCLMarcos Georgiades, PhD Candidate, Neurobiology and Biophysics, UCLLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1687512021-09-29T03:03:14Z2021-09-29T03:03:14ZMale mosquitoes don’t want your blood, but they still find you very attractive<figure><img src="https://images.theconversation.com/files/423722/original/file-20210929-18-14vn404.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1920%2C1080&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Perran Ross</span>, <span class="license">Author provided</span></span></figcaption></figure><p>The whine of the mosquito is unpleasant and often inescapable outdoors on summer evenings. Mosquitoes <a href="https://www.sciencedirect.com/science/article/pii/S096098221500740X">track you down from tens of metres away</a> by sensing carbon dioxide in the air you breathe out. Within seconds, they home in on exposed skin and feast on your blood with <a href="https://www.kqed.org/science/728086/how-mosquitoes-use-six-needles-to-suck-your-blood">an array of specialized needles</a>.</p>
<p>Only female mosquitoes drink blood, which is how they spread deadly diseases like dengue fever and malaria. Males mosquitoes are harmless, mostly feeding on nectar, but our new research confirms they are just as annoying as female mosquitoes.</p>
<p><a href="https://academic.oup.com/jme/advance-article/doi/10.1093/jme/tjab164/6374962">Our study</a>, published in the Journal of Medical Entomology, dispels a <a href="https://www.rockefeller.edu/news/30149-male-mosquitoes-leave-humans-alone/">common misconception</a> that male mosquitoes avoid people. In fact, male mosquitoes from at least one common species probably like you just as much as females do – but the reason for their fondness and the way they express it are very different.</p>
<p><img src="https://cdn.theconversation.com/static_files/files/1792/ezgif.com-gif-maker.gif?1632877165" width="100%" alt="Male mosquitoes flying around an exposed hand."></p>
<h2>The backyard and the laboratory</h2>
<p>We used a simple experiment to test if male mosquitoes from the species <em>Aedes aegypti</em>, which spreads dengue, seek out people. We released mosquitoes into a large arena, the size of a suburban yard, and had willing subjects sit in a chair as bait. Cameras facing the subjects filmed mosquitoes as they flew nearby. We confirmed that male mosquitoes are indeed attracted to people.</p>
<p>Female mosquitoes are after your blood, but male mosquitoes just want to hang out. In our experiments, male mosquitoes continuously swarmed around people but rarely landed. By contrast, female mosquitoes land, drink their fill and then fly away to rest.</p>
<p><a href="https://doi.org/10.1016/0035-9203(95)90406-9">People differ in their attractiveness to female mosquitoes</a>, and this also holds true for male mosquitoes. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/feel-like-youre-a-mozzie-magnet-its-true-mosquitoes-prefer-to-bite-some-people-over-others-128788">Feel like you're a mozzie magnet? It's true – mosquitoes prefer to bite some people over others</a>
</strong>
</em>
</p>
<hr>
<p>Of the two participants in our study, one person was about three times as attractive as the other. The basis of this variation is not fully understood, but the mix of chemicals you emit from your skin is likely to be important.</p>
<p>We also tested mosquito attraction in small cages in the laboratory. In this environment, males showed no apparent interest in people, while female mosquitoes did. This is likely because <a href="https://elifesciences.org/articles/63982">male mosquitoes can’t detect some of the close-range signals that female mosquitoes can</a>.</p>
<h2>If they’re not after our blood, what do male mosquitoes want?</h2>
<p>Why are male mosquitoes interested in people if they can’t feed on your blood? We think it’s all about finding the females. Since female mosquitoes are often around people, male mosquitoes that have the same inclination should have greater reproductive success. </p>
<p>But more work is needed to understand the how and why. Almost all behavioural research so far has focused on female mosquitoes.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-genetic-approach-to-mosquitoes-can-stop-them-spreading-infections-52982">A genetic approach to mosquitoes can stop them spreading infections</a>
</strong>
</em>
</p>
<hr>
<p>However, there is growing interest in <a href="https://www.nature.com/articles/s41586-019-1407-9">releasing modified male mosquitoes to sterilise female mosquitoes</a>, which gives our research practical applications.</p>
<p>So, not all mosquitoes you see are out for your blood. Some just want you as their wingman, whether you like it or not.</p><img src="https://counter.theconversation.com/content/168751/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Perran Ross 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>Male mosquitoes gather around humans, likely in an attempt to mate with blood-sucking females.Perran Ross, Postdoctoral research fellow, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1610552021-06-23T12:22:12Z2021-06-23T12:22:12ZI have city kids make comic books to create a buzz about mosquitoes and ecology<figure><img src="https://images.theconversation.com/files/407115/original/file-20210617-21-u3xpfl.jpg?ixlib=rb-1.1.0&rect=7%2C0%2C5296%2C2988&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Campers at the "Mosquitoes & Me" summer camp in Des Moines, Iowa, learn about mosquito science through hands-on outdoor activities. </span> <span class="attribution"><span class="source">Katherine R. Bruna</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>If humans and mosquitoes had a battle at the end of the world, who would win? That’s the question I pose to 30 young kids each summer during a two-week camp called “<a href="https://youtu.be/0M3uxRbN3Mc">Mosquitoes & Me</a>” in Des Moines, Iowa. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/0M3uxRbN3Mc?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The ‘Mosquito and Me’ summer camp in Des Moines, Iowa.</span></figcaption>
</figure>
<p>I am an <a href="https://scholar.google.com/citations?user=azAMQkMAAAAJ&hl=en">educational anthropologist</a> who studies the cultural dynamics of science education. Along with my colleagues <a href="http://mcevbd.wisc.edu/partners/university-of-wisconsin-madison/dr-lyric-bartholomay">Lyric Bartholomay</a> and <a href="https://nihsepa.org/community/contact/erickson-sara/">Sara Erickson</a>, who help run the camp, we have the young camp participants explore the “end-of-world battle” question as they learn about mosquito biology, ecology and disease transmission. Based on what the kids learn from their hands-on activities, they design a mosquito comic book character that is either a hero or a villain. </p>
<p>Since this approach was such a big hit, we worked with Marvel Comics artist <a href="https://bobhall.com/about-me/">Bob Hall</a> to convert <a href="https://research.hs.iastate.edu/urban-ecosystem-project/">“Mosquitoes & Me”</a> into an <a href="https://www.nebraskapress.unl.edu/nebraska/9781496224347/">actual comic book</a>. Some of our young scientists drew images of themselves and made up catchy public health slogans for a page about mosquito control. The idea is to reach kids who can’t attend “Mosquitoes & Me” camp by offering to teach them cool facts about mosquitoes. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/407268/original/file-20210618-22-8mtifw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two pages from a comic book." src="https://images.theconversation.com/files/407268/original/file-20210618-22-8mtifw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/407268/original/file-20210618-22-8mtifw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/407268/original/file-20210618-22-8mtifw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/407268/original/file-20210618-22-8mtifw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/407268/original/file-20210618-22-8mtifw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/407268/original/file-20210618-22-8mtifw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/407268/original/file-20210618-22-8mtifw.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">A page from the ‘Mosquitoes & Me’ comic book.</span>
<span class="attribution"><span class="source">Katherine R. Bruna</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Feeding habits</h2>
<p>Before we make the comic book, some serious science has to take place. While at the camp, a group of mostly Black and Latino elementary and middle schoolers who are interested in science work in teams. They learn everything they need to know to decide whether humans or mosquitoes would win in an end-of-the-world battle. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/405708/original/file-20210610-13-13bfnsm.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A young girl looks at a mosquito through a microscope." src="https://images.theconversation.com/files/405708/original/file-20210610-13-13bfnsm.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/405708/original/file-20210610-13-13bfnsm.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/405708/original/file-20210610-13-13bfnsm.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/405708/original/file-20210610-13-13bfnsm.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/405708/original/file-20210610-13-13bfnsm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/405708/original/file-20210610-13-13bfnsm.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/405708/original/file-20210610-13-13bfnsm.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Children at the ‘Mosquitoes & Me’ summer camp have the opportunity to study mosquitoes.</span>
<span class="attribution"><span class="source">Katherina R. Bruna</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>They explore mosquito ecology by looking for larvae in local water spots. <a href="https://www.reconnectwithnature.org/news-events/the-buzz/world-without-mosquitoes-not-as-easy-as-it-seems">They examine the important role</a> that mosquitoes play in the ecosystem. They tackle the logistics of disease transmission by thinking through whether mosquitoes actually “bite” or “suck.” And they learn about mosquito biology by feeding larvae foods made from their own kitchens.</p>
<p>The activities engage them in authentic science practices like data tabling, microscope use and dissection. At the end of camp, they create public service announcements to teach mosquito control and disease prevention.</p>
<h2>Taking a more involved approach</h2>
<p>Research has found that students who experience hands-on learning <a href="https://www.prweb.com/releases/stem-education/science-research-study/prweb12128837.htm">outperform students</a> who receive more traditional instruction. Most importantly, hands-on science gives them an experience with “object intimacy.” This is a feeling of developing a relationship with the thing they’re studying.</p>
<p>Broadening participation by helping young people “<a href="https://www.worldcat.org/title/falling-for-science-objects-in-mind/oclc/762197870&referer=brief_results">fall for science</a>” is imperative in increasing diversity in entomology – a field in which <a href="https://www.sciencenews.org/article/black-scientists-disparities-representation-stem-science">disparities persist</a>, particularly for African Americans. </p>
<p><a href="https://doi.org/10.1093/ae/60.3.146">Less than 2% of the membership</a> of the Entomological Society of America identifies as African American.</p>
<p>Students from underrepresented backgrounds who understand how science can serve their communities show <a href="https://doi.org/10.1187/cbe.16-01-0067">stronger motivation</a> to persist in science studies. Our overarching goal is that the hands-on approach of “Mosquitoes & Me” helps youths, especially those who aren’t engaged by a traditional school science curriculum, see the relevance of science – and especially entomology – to themselves and their community.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/407068/original/file-20210617-17-budo36.png?ixlib=rb-1.1.0&rect=1%2C0%2C796%2C850&q=45&auto=format&w=1000&fit=clip"><img alt="A young girl looks at a flask with larvae food in it." src="https://images.theconversation.com/files/407068/original/file-20210617-17-budo36.png?ixlib=rb-1.1.0&rect=1%2C0%2C796%2C850&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/407068/original/file-20210617-17-budo36.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=639&fit=crop&dpr=1 600w, https://images.theconversation.com/files/407068/original/file-20210617-17-budo36.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=639&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/407068/original/file-20210617-17-budo36.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=639&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/407068/original/file-20210617-17-budo36.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=803&fit=crop&dpr=1 754w, https://images.theconversation.com/files/407068/original/file-20210617-17-budo36.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=803&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/407068/original/file-20210617-17-budo36.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=803&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 camper observes the water conditions of her larvae.</span>
<span class="attribution"><span class="source">Katherine R. Bruna</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Solving real-world problems</h2>
<p>In 2019 roughly <a href="https://www.who.int/news-room/fact-sheets/detail/malaria">409,000 people died from malaria</a> worldwide. Even though the “skeeter scientists” of “Mosquitoes & Me” summer camps live far away from the countries where malaria remains a dire threat, scientists anticipate that climate change will <a href="https://doi.org/10.1038/s41590-020-0648-y">exacerbate conditions</a> in the U.S. – especially in urban areas – for <a href="https://doi.org/10.1038/s41598-019-51787-5">other mosquito-borne diseases</a>. These include dengue, West Nile virus, chikungunya Zika and yellow fever. </p>
<p>Community members play a significant role in reducing the prevalence of mosquitoes in urban areas. Since entomology is a predominantly white field, residents of urban neighborhoods may be <a href="https://doi.org/10.1038/s41598-018-34161-9">distrustful of entomologists</a> who, to do their work, need to place traps in and around their homes or neighborhoods and do “surveillance” on trash, flower pots, toys, tires and other items that collect water and cause mosquito habitats. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/405727/original/file-20210610-13-10pvgs.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Pages from the 'Mosquitoes & Me' comic book." src="https://images.theconversation.com/files/405727/original/file-20210610-13-10pvgs.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/405727/original/file-20210610-13-10pvgs.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=224&fit=crop&dpr=1 600w, https://images.theconversation.com/files/405727/original/file-20210610-13-10pvgs.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=224&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/405727/original/file-20210610-13-10pvgs.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=224&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/405727/original/file-20210610-13-10pvgs.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=281&fit=crop&dpr=1 754w, https://images.theconversation.com/files/405727/original/file-20210610-13-10pvgs.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=281&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/405727/original/file-20210610-13-10pvgs.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=281&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Pages from the comic book explaining the life cycle and how ‘Mosquitoes & Me’ campers look for mosquitoes in local parks.</span>
<span class="attribution"><span class="source">Katherine R. Bruna</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The young skeeter scientists of “Mosquitoes & Me” can help their families make sure that everyday items don’t end up holding standing water and become attractive habitats for mosquito moms to lay their eggs.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/405704/original/file-20210610-25-1fbhxif.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A page from a comic book where rats roam around a wasted world." src="https://images.theconversation.com/files/405704/original/file-20210610-25-1fbhxif.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/405704/original/file-20210610-25-1fbhxif.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=923&fit=crop&dpr=1 600w, https://images.theconversation.com/files/405704/original/file-20210610-25-1fbhxif.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=923&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/405704/original/file-20210610-25-1fbhxif.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=923&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/405704/original/file-20210610-25-1fbhxif.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1159&fit=crop&dpr=1 754w, https://images.theconversation.com/files/405704/original/file-20210610-25-1fbhxif.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1159&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/405704/original/file-20210610-25-1fbhxif.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1159&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Pages from the ‘Mosqutio and Me’ comic book where rats run around a dystopian world.</span>
<span class="attribution"><span class="source">Katherine R. Bruna</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>“Mosquitoes Suck!” begins with humans winning the end-of-world battle. But promoting environmental education that avoids such a standoff is the prevailing theme. If humans drive mosquitoes to extinction, we will all lose. They are an essential part of life’s intricate interdependence. </p>
<p>Through “Mosquitoes & Me,” we are helping a future generation of diverse potential scientists and their educators fall for mosquitoes, and for science.</p>
<p>[<em>Over 106,000 readers rely on The Conversation’s newsletter to understand the world.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=100Ksignup">Sign up today</a>.]</p><img src="https://counter.theconversation.com/content/161055/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Katherine Richardson Bruna receives funding from the National Institutes of Health. </span></em></p>A hands-on approach to learning about bugs can help students from urban communities take an interest in science.Katherine Richardson Bruna, Professor, Sociocultural Studies of Education, Iowa State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1501832020-12-24T21:25:35Z2020-12-24T21:25:35ZMozzies biting? Here’s how to choose a repellent (and how to use it for the best protection)<figure><img src="https://images.theconversation.com/files/373012/original/file-20201204-23-67p3hy.jpg?ixlib=rb-1.1.0&rect=53%2C0%2C6000%2C3997&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>Mosquitoes are an inevitable part of the Australian summer. And this year, with COVID a consideration, we might be spending more time outdoors than usual.</p>
<p>Supermarkets and pharmacies are stocked with a wide range of insect repellents including aerosols, creams, gels, sprays, roll-ons and wipes. There are even wristbands, fabric sprays, coils, sticks, plug-in devices and smartphone apps.</p>
<p>But not all products that purport to protect us from mosquito bites are equal.</p>
<p>So, how do you choose and use a repellent to best protect you and your family from mosquito bites?</p>
<h2>The key ingredients</h2>
<p>Health authorities <a href="https://www.frontiersin.org/articles/10.3389/fpubh.2019.00054/full">around Australia</a> recommend using insect repellents that you apply directly to exposed skin to prevent mosquito bites and reduce the risk of <a href="https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1005070">mosquito-borne diseases</a>. </p>
<p>All insect repellents sold in Australia must be registered with the Australian Pesticides and Veterinary Medicines Authority (<a href="https://apvma.gov.au/">APVMA</a>), which checks that products are safe and effective. </p>
<p>Despite the wide range of formulations available, there are only a small number of active ingredients registered for use. So any insect repellent on the shelves in Australia will contain at least one of these ingredients. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/371638/original/file-20201126-21-stabyq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/371638/original/file-20201126-21-stabyq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/371638/original/file-20201126-21-stabyq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/371638/original/file-20201126-21-stabyq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/371638/original/file-20201126-21-stabyq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/371638/original/file-20201126-21-stabyq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/371638/original/file-20201126-21-stabyq.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">Spending more time outdoors means a greater chance of mosquito bites.</span>
<span class="attribution"><span class="source">David Todd McCarty/Unsplash</span></span>
</figcaption>
</figure>
<p><strong>Diethyltoumide</strong> (DEET) is one of the <a href="https://www.phrp.com.au/wp-content/uploads/2016/12/PHRPDec16-Mosquito-031Dec16.pdf">most widely used and recommended</a> repellents across the world. It <a href="https://academic.oup.com/jme/article/41/3/414/917125">effectively prevents mosquito bites</a> and has repeatedly been shown to have <a href="https://malariajournal.biomedcentral.com/articles/10.1186/s12936-020-03217-5">minimal adverse side effects</a> if used as directed. </p>
<p>DEET formulations in Australia are available in a range of concentrations, as low as 10% through to “heavy duty” or “tropical strength” products that may be as high as 80%.</p>
<p><strong>Picaridin</strong> is a common ingredient in local mosquito repellent formulations and <a href="https://academic.oup.com/jme/article/41/3/414/917125">effectively reduces mosquito bites</a>. Like DEET, it has been <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0172566">assessed as safe to use</a>. Most formulations in Australia have concentrations of less than 20%.</p>
<p><strong>Oil of lemon eucalyptus</strong> is increasingly common in mosquito repellents. The chemical, p-menthane-3,8-diol, is derived from the leaves of the lemon-scented gum <a href="https://bioone.org/journals/journal-of-the-american-mosquito-control-association/volume-22/issue-3/8756-971X(2006)22%5B507:PARBMR%5D2.0.CO;2/PMD-a-Registered-Botanical-Mosquito-Repellent-with-Deet-Like-Efficacy/10.2987/8756-971X(2006)22%5B507:PARBMR%5D2.0.CO;2.full"><em>Corymbia citriodora</em></a>. </p>
<p>This ingredient is a byproduct of the distillation process, not an essential oil extracted from the leaves of the plant. This is important, as this product is a much more effective repellent than <a href="https://bioone.org/journals/journal-of-the-american-mosquito-control-association/volume-25/issue-3/09-0016.1/Are-Commercially-Available-Essential-Oils-from-Australian-Native-Plants-Repellent/10.2987/09-0016.1.full">essential oils</a> (we’ll get to these alternatives shortly). </p>
<p>Formulations containing oil of lemon eucalyptus <a href="https://meridian.allenpress.com/jamca/article/35/3/186/438795">provide comparable protection</a> to DEET-based repellents.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/la-nina-will-give-us-a-wet-summer-thats-great-weather-for-mozzies-147180">La Niña will give us a wet summer. That's great weather for mozzies</a>
</strong>
</em>
</p>
<hr>
<p>The active ingredient in the repellent will be listed on the packaging, along with the concentration.</p>
<p>Any insect repellent that contains these products should provide protection against biting mosquitoes. But the stronger the formulation, the longer the protection will last. </p>
<p>If you’re only outside for a couple of hours, say, in the backyard, there’s really no need for a high-concentration formulation. But if you’re going for a long bushwalk or fishing trip, pick a high-concentration product (regardless of the active ingredient).</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/374589/original/file-20201213-17-1bll6b0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/374589/original/file-20201213-17-1bll6b0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/374589/original/file-20201213-17-1bll6b0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/374589/original/file-20201213-17-1bll6b0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/374589/original/file-20201213-17-1bll6b0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/374589/original/file-20201213-17-1bll6b0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/374589/original/file-20201213-17-1bll6b0.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">Mosquitoes are one of the most common insect pests in Australia.</span>
<span class="attribution"><span class="source">A/Prof Cameron Webb (NSW Health Pathology)</span></span>
</figcaption>
</figure>
<h2>How you use it matters too</h2>
<p>A dab here and there, or spraying repellent into the air around you, as you might a perfume, won’t provide much protection. </p>
<p>These products need to be applied thinly and evenly to all exposed areas of skin. Think of repellents as camouflaging us from mosquitoes on the lookout for blood.</p>
<p>While an aerosol or pump spray may allow for application direct from the container, you’ll need to rub creams, roll-ons and gels into your skin.</p>
<p>That doesn’t necessarily mean one is better than the other. But when choosing a formulation, think about which one you feel you’ll be able to apply thoroughly most easily.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/feel-like-youre-a-mozzie-magnet-its-true-mosquitoes-prefer-to-bite-some-people-over-others-128788">Feel like you're a mozzie magnet? It's true – mosquitoes prefer to bite some people over others</a>
</strong>
</em>
</p>
<hr>
<h2>What about ‘natural’ alternatives?</h2>
<p>Some “natural” formulations that contain tea tree oil and other plant-based active ingredients have APVMA registration. Products sold at local markets or online may not be registered.</p>
<p>Notably, products that contain plant-based repellents <a href="https://theconversation.com/chemical-or-natural-whats-the-best-way-to-repel-mozzies-36879">generally don’t provide long-lasting protection</a> from mosquito bites. </p>
<p>If you prefer to use products <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1440-6055.2009.00736.x">containing tea-tree oil</a> or other botanical repellents, you need to be prepared to reapply much more frequently than with DEET, picaridin or oil of lemon eucalyptus formulations.</p>
<p>And avoid making up your own insect repellents from essential oils. Without the checks in place associated with APVMA-registered repellents, there may be a greater risk of <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1440-0960.2007.00341.x">adverse skin reactions</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/371421/original/file-20201126-15-jjc31k.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/371421/original/file-20201126-15-jjc31k.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/371421/original/file-20201126-15-jjc31k.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/371421/original/file-20201126-15-jjc31k.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/371421/original/file-20201126-15-jjc31k.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/371421/original/file-20201126-15-jjc31k.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/371421/original/file-20201126-15-jjc31k.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">Mosquito repellents come in a range of formulations.</span>
<span class="attribution"><span class="source">A/Prof Cameron Webb (NSW Health Pathology)</span></span>
</figcaption>
</figure>
<h2>Can anything else help?</h2>
<p>There’s no evidence mosquito-repellent <a href="https://theconversation.com/health-check-do-wrist-bands-work-to-repel-mozzies-50186">wristbands</a> or <a href="https://theconversation.com/the-buzz-from-your-smartphone-wont-stop-mosquito-bites-92611">smartphone apps</a> will protect you from mosquito bites.</p>
<p>A range of <a href="https://bioone.org/journals/journal-of-the-american-mosquito-control-association/volume-24/issue-1/8756-971X(2008)24%5B154:AOEOCT%5D2.0.CO;2/Ability-of-Essential-Oil-Candles-to-Repel-Biting-Insects-in/10.2987/8756-971X(2008)24%5B154:AOEOCT%5D2.0.CO;2.short">candles</a>, <a href="https://www.sciencedirect.com/science/article/abs/pii/S1226861519302791">coils</a>, <a href="https://bioone.org/journals/Journal-of-the-American-Mosquito-Control-Association/volume-22/issue-1/8756-971X(2006)22%5B158:FEONMS%5D2.0.CO;2/FIELD-EVALUATION-OF-NEW-MOUNTAIN-SANDALWOOD-MOSQUITO-STICKSsup-supAND-NEW/10.2987/8756-971X(2006)22%5B158:FEONMS%5D2.0.CO;2.short">sticks</a>, <a href="https://meridian.allenpress.com/jamca/article/36/2/120/446434">plug-in and fan devices</a> and <a href="https://theconversation.com/mozzie-repellent-clothing-might-stop-some-bites-but-youll-still-need-a-cream-or-spray-107266">insecticide-treated</a> clothing offer varying assistance in reducing mosquito bites. But unfortunately, none of these provides complete protection and are always best combined with topical mosquito repellents.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-can-i-eat-to-stop-mosquitoes-biting-me-87178">What can I eat to stop mosquitoes biting me?</a>
</strong>
</em>
</p>
<hr>
<p>Some people perceive so-called “chemical” repellents as <a href="https://malariajournal.biomedcentral.com/articles/10.1186/s12936-020-03217-5">posing a risk to our health</a>. But, in most instances, they can be safely applied to anyone over 12 months of age. (For babies, it’s best to provide physical protection, such as covering the stroller with a mosquito net.)</p>
<p>It’s also often said these traditional repellents are unpleasant to use. But even though the active ingredients haven’t changed much, the cosmetic constituents of insect repellents have greatly improved in recent years.</p>
<p>To get you through summer, choose a repellent formulation registered with APVMA. Pick whichever one you find easiest to spread over the skin to provide complete cover. And always check the instructions on the label.</p><img src="https://counter.theconversation.com/content/150183/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Associate Professor Cameron Webb and the Department of Medical Entomology, NSW Health Pathology, have been engaged by a wide range of insecticide manufacturers to provide testing of products and provide expert advice on, specifically, mosquito biology. Cameron has also received funding from local, state, federal and international agencies to undertake research into mosquito-borne disease surveillance and management strategies.</span></em></p>Summer is here, and so are the mozzies. So what do you need to consider when you’re picking a mosquito repellent?Cameron Webb, Clinical Associate Professor and Principal Hospital Scientist, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1471802020-10-04T18:54:32Z2020-10-04T18:54:32ZLa Niña will give us a wet summer. That’s great weather for mozzies<figure><img src="https://images.theconversation.com/files/360682/original/file-20200930-20-96ai8k.jpg?ixlib=rb-1.1.0&rect=0%2C17%2C5700%2C3129&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://flic.kr/p/Qd5btz">Geoff Whalan/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>The return of the <a href="http://www.bom.gov.au/climate/updates/articles/a020.shtml">La Niña</a> weather pattern will see a wetter spring and summer in many parts of Australia.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1310812075241816065"}"></div></p>
<p>We know mosquitoes need water to complete their life cycle. So does this mean Australia can expect a bumper mozzie season? How about a rise in mosquito-borne disease?</p>
<p>While we’ve seen more mosquitoes during past La Niña events, and we may well see more mosquitoes this year, this doesn’t necessarily mean we’ll see more related disease.</p>
<p>This depends on a range of other factors, including local wildlife, essential to the life cycle of disease-transmitting mosquitoes.</p>
<h2>What is La Niña?</h2>
<p>La Niña is a phase of the <a href="https://www.ncdc.noaa.gov/teleconnections/enso/enso-tech.php">El Niño-Southern Oscillation</a>, a pattern of ocean and atmospheric circulations over the Pacific Ocean. </p>
<p>While <a href="http://www.bom.gov.au/climate/updates/articles/a008-el-nino-and-australia.shtml">El Niño</a> is generally associated with hot and dry conditions, La Niña is the opposite. La Niña brings slightly cooler but wetter conditions to many parts of Australia. During this phase, northern and eastern Australia are particularly likely to <a href="https://www.abc.net.au/news/2020-09-29/bom-declares-la-nina-wet-conditions-likely-for-eastern-australia/12617528">have a wetter spring and summer</a>.</p>
<p>Australia’s most recent significant La Niña events were in <a href="http://www.bom.gov.au/climate/enso/history/ln-2010-12/">2010-11 and 2011-12</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-el-nino-and-la-nina-27719">Explainer: El Niño and La Niña</a>
</strong>
</em>
</p>
<hr>
<h2>Why is wet weather important for mosquitoes?</h2>
<p>Mosquitoes lay their eggs on or around stagnant or still water. This could be water in ponds, backyard plant containers, clogged gutters, floodplains or wetlands. Mosquito larvae (or “wrigglers”) hatch and spend the next week or so in the water before emerging as adults and buzzing off to look for blood. </p>
<p>If the water dries up, they die. But the more rain we get, the more opportunities for mosquitoes to multiply.</p>
<figure class="align-center ">
<img alt="Mosquito biting a person's hand" src="https://images.theconversation.com/files/360981/original/file-20201001-18-12paypy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/360981/original/file-20201001-18-12paypy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=426&fit=crop&dpr=1 600w, https://images.theconversation.com/files/360981/original/file-20201001-18-12paypy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=426&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/360981/original/file-20201001-18-12paypy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=426&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/360981/original/file-20201001-18-12paypy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=535&fit=crop&dpr=1 754w, https://images.theconversation.com/files/360981/original/file-20201001-18-12paypy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=535&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/360981/original/file-20201001-18-12paypy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=535&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Mosquito populations often increase after wet weather.</span>
<span class="attribution"><span class="source">Cameron Webb/Author provided</span></span>
</figcaption>
</figure>
<p>Mosquitoes are more than just a nuisance. When they bite, they can transmit viruses or bacteria into our blood to make us sick. </p>
<p>While Australia is free of major outbreaks of internationally significant diseases such as dengue or malaria, every year mosquitoes still cause debilitating diseases.</p>
<p>These include transmission of <a href="https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1005070">Ross River virus</a>, <a href="https://www.health.nsw.gov.au/Infectious/factsheets/Pages/barmah_forest_virus_infection.aspx">Barmah Forest virus</a> and the potentially fatal <a href="https://www.mja.com.au/journal/2012/196/5/murray-valley-encephalitis-review-clinical-features-diagnosis-and-treatment">Murray Valley encephalitis virus</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-is-murray-valley-encephalitis-virus-112212">Explainer: what is Murray Valley encephalitis virus?</a>
</strong>
</em>
</p>
<hr>
<h2>What happens when we get more rain?</h2>
<p>We’ve know for a long time floods provide plenty of water to boost the abundance of mosquitoes. With more mosquitoes about, there is a <a href="https://academic.oup.com/jme/article/57/1/241/5532730">higher risk</a> of mosquito-borne disease. </p>
<p>The amount of rainfall each summer is also a key <a href="https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0008621">predictor</a> for seasonal outbreaks of mosquito-borne disease, especially Ross River virus.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-is-ross-river-virus-and-how-is-it-treated-37889">Explainer: what is Ross River virus and how is it treated?</a>
</strong>
</em>
</p>
<hr>
<p>Inland regions of Queensland, New South Wales and Victoria, especially within the <a href="https://www.mdba.gov.au/importance-murray-darling-basin">Murray Darling Basin</a>, are particularly prone to “boom and bust” cycles of mosquitoes and mosquito-borne disease. </p>
<p>In these regions, the El Niño-Southern Oscillation is thought to play an important role in <a href="https://www.liebertpub.com/doi/abs/10.1089/vbz.2004.4.210">driving the risks</a> of mosquito-borne disease.</p>
<p>The hot and dry conditions of El Niño <a href="https://theconversation.com/will-the-arrival-of-el-nino-mean-fewer-mosquitoes-this-summer-102496">aren’t typically ideal</a> for mosquitoes.</p>
<p>But historically, major outbreaks of mosquito-borne disease have been associated with extensive inland flooding. This flooding is typically associated with prevailing La Niña conditions. </p>
<p>For instance, outbreaks of Murray Valley encephalitis in the 1950s and 1970s had <a href="https://pubmed.ncbi.nlm.nih.gov/8031248/">significant impacts</a> on human health and occurred at a time of <a href="http://www.bom.gov.au/climate/enso/lnlist/">moderate-to-strong La Niña events</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/our-new-model-shows-australia-can-expect-11-tropical-cyclones-this-season-146318">Our new model shows Australia can expect 11 tropical cyclones this season</a>
</strong>
</em>
</p>
<hr>
<p>Over the past decade, when La Niña has brought above average rainfall and flooding, there have also been outbreaks of mosquito-borne disease.</p>
<p>These have included:</p>
<ul>
<li><p>Victoria’s record breaking epidemic of <a href="https://www.sciencedirect.com/science/article/pii/S1755436519300659">Ross River virus</a> in 2016-17 after extensive inland flooding</p></li>
<li><p>southeast Queensland’s outbreak of Ross River virus in 2014-15, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6874252/">partly attributed</a> to an increase in mosquitoes associated with freshwater habitats after seasonal rainfall</p></li>
<li><p>eastern Australia’s major outbreaks of mosquito-borne disease associated with extensive flooding during two <a href="http://www.bom.gov.au/climate/enso/history/La-Nina-2010-12.pdf">record breaking La Niñas</a> between 2010 and 2012. These included <a href="https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0002656">Murray Valley encaphalitis</a> and mosquito-borne illness <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3358055/">in horses</a> caused by the closely related West Nile virus (Kunjin strain).</p></li>
</ul>
<h2>We can’t say for certain there will be more disease</h2>
<p>History and our understanding of mosquito biology means that with the prospect of more rain, we should expect more mosquitoes. But even when there are floods, predicting outbreaks of mosquito-borne disease <a href="https://theconversation.com/after-the-floods-come-the-mosquitoes-but-the-disease-risk-is-more-difficult-to-predict-111173">isn’t always simple</a>.</p>
<p>This is because of the role <a href="https://theconversation.com/how-australian-wildlife-spread-and-suppress-ross-river-virus-107267">wildlife plays</a> in the transmission cycles of Ross River virus and Murray Valley encephalitis virus.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/after-the-floods-come-the-mosquitoes-but-the-disease-risk-is-more-difficult-to-predict-111173">After the floods come the mosquitoes – but the disease risk is more difficult to predict</a>
</strong>
</em>
</p>
<hr>
<p>In these cases, mosquitoes don’t hatch out of the floodwaters carrying viruses, ready to bite humans. These mosquitoes first have to bite wildlife, which is where they pick up the virus. Then, they bite humans.</p>
<p>So how local animals, such as kangaroos, wallabies and water birds, respond to rainfall and flooding will play a role in determining the risk of mosquito-borne disease. In some cases, flooding of inland wetlands can see an <a href="https://www.abc.net.au/news/2016-10-26/flooding-triggers-waterbird-breeding-event-in-nsw-west/7965570">explosion in local water bird populations</a>.</p>
<h2>How can we reduce the risks?</h2>
<p>There isn’t much we can do to change the weather but we can take steps to reduce the impacts of mosquitoes.</p>
<p>Wearing <a href="https://theconversation.com/the-best-and-worst-ways-to-beat-mosquito-bites-70274">insect repellent when outdoors</a> will help reduce your chance of mosquito bites. But it’s also important to tip out, cover up, or throw away any water-holding containers in our backyard, at least once a week.</p>
<p>Local authorities in many parts of Australia also <a href="https://theconversation.com/the-worst-year-for-mosquitoes-ever-heres-how-we-find-out-68433">undertake surveillance</a> of mosquitoes and <a href="https://www.abc.net.au/local/stories/2013/03/12/3713837.htm">mosquito-borne pathogens</a>. This provides an early warning of the risk of mosquito-borne disease.</p>
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Read more:
<a href="https://theconversation.com/the-worst-year-for-mosquitoes-ever-heres-how-we-find-out-68433">The worst year for mosquitoes ever? Here's how we find out</a>
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<img src="https://counter.theconversation.com/content/147180/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>Mosquitoes love the wetter weather La Niña brings to some parts of Australia. But will we see more mosquito-borne disease?Cameron Webb, Clinical Associate Professor and Principal Hospital Scientist, University of SydneyLicensed 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/1234752019-09-17T13:12:50Z2019-09-17T13:12:50ZDams increase the risk of malaria. Here’s why<figure><img src="https://images.theconversation.com/files/292269/original/file-20190912-190031-rvcefl.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>Many people in Africa are <a href="https://www.washingtonpost.com/news/monkey-cage/wp/2017/10/30/four-things-you-should-know-about-food-security-in-africa/">food insecure</a>, vulnerable to <a href="https://theconversation.com/why-africa-is-particularly-vulnerable-to-climate-change-41775">shifts in climate</a> and do not have <a href="https://theconversation.com/millions-of-urban-africans-still-dont-have-electricity-heres-what-can-be-done-92211">access to electricity</a>. There’s also a problem with accessing reliable, clean water, particularly in places with irregular rains.</p>
<p><a href="https://www.internationalrivers.org/resources/what-is-driving-dams-in-africa-1695">Building dams</a> is one way that African countries are trying to address these myriad issues. A number of large and small dams are currently under construction, particularly <a href="http://www.hydrocoop.org/which-dams-in-africa/">in sub-Saharan Africa</a>. </p>
<p>But while dams could solve some problems, it may also bring new ones – like malaria. Water is crucial to the spread of this mosquito-borne disease. That’s because mosquitoes breed and lay their eggs in or near bodies of water. The insects prefer shallow pools for these purposes, and dams provide shorelines that offer just this: many shallow pools.</p>
<p>The number of people living close to (less than 5 km away) large dam reservoirs in sub-Saharan Africa increased from around 14 million to about 19 million between 2000 and 2015, according to <a href="https://malariajournal.biomedcentral.com/articles/10.1186/s12936-019-2933-5">our study</a>. Nearly <a href="https://malariajournal.biomedcentral.com/articles/10.1186/s12936-019-2933-5">75%</a> of the population stays in areas where there is malaria. During the same 15 year period, the number of large dams <a href="https://malariajournal.biomedcentral.com/articles/10.1186/s12936-019-2933-5">increased from 884 to 919</a> in Africa. These figures are conservative, since only two-third of African dams are registered in the <a href="https://www.icold-cigb.org/GB/world_register/world_register_of_dams.asp">World Register of Dams</a> database.</p>
<p>At least <a href="http://www.iwmi.cgiar.org/Publications/Water_Policy_Briefs/PDF/wpb40.pdf">one million malaria cases</a> can be attributed to large dams in Africa each year. But the relationship between dams and malaria is not entirely straightforward. Dams don’t always increase malaria cases. When they do, the degree of increase is not uniform. So it’s important to explore the factors that determine malaria risk around Africa’s large dams.</p>
<p>That’s what <a href="https://malariajournal.biomedcentral.com/articles/10.1186/s12936-019-2933-5">our study</a> set out to do. Using topographic data, we unpacked the relationship between large dams and their characteristics, like altitude and rainfall, linked to malaria in sub-Saharan Africa. The study used satellite data to accurately measure elevation, slope and surface areas of African reservoirs in four time periods – 2000, 2005, 2010 and 2015.</p>
<p>We found that there were a number of factors that increases the risk of malaria in areas close to larger dams. The slope of the dams shoreline was the most important risk factor.</p>
<h2>Key findings</h2>
<p>We looked at a number of environmental variables such as altitude, rainfall, temperature and the slope of the reservoir shoreline to identify factors that contribute to malaria transmission in a given region. Here’s why we chose those four factors.</p>
<p><strong>Altitude</strong>: Malaria used to be a lowland disease. But <a href="https://iopscience.iop.org/article/10.1088/1748-9326/aa64e6/meta">evidence shows</a> that climate change is helping malaria encroach to highlands where the disease was uncommon.</p>
<p><strong>Rainfall</strong>: This governs the occurrence of rain pools and puddles which are favourable habitats for mosquito breeding. Rain affects the nature of the shoreline of dams by creating puddles around the reservoir shoreline. </p>
<p><strong>Temperature</strong>: This determines the rate of a mosquito’s growth in the water and the development of the malaria parasite inside adult mosquitoes. Similarly, biophysical factors such as geography and land use can influence the suitability of habitats for mosquito development. </p>
<p><strong>Slope</strong>: This is the most important predictor of the level of malaria around dam. Our analysis showed that in regions which are otherwise suitable for mosquito breeding, the slope of the reservoir shore plays the largest critical role in determining the occurrence of malaria in the vicinity of dams. Reservoirs with higher slope at shoreline have lower malaria impacts. Conversely, reservoirs with lower slope at shoreline have higher malaria impacts.</p>
<p>Mosquitoes prefer to breed in shallow puddles created around shorelines which are often free of predators such as fish and tadpoles. Hydrologically, slope determines how likely an area is to retain surface water. Gentle slope generally corresponds to poor drainage, promoting the persistence of surface water bodies and the formation of stable pools that are good habitats for mosquito breeding. </p>
<p>In contrast, a steeper slope facilitates drainage. It reduces the likelihood that pools will form for periods long enough for mosquitoes to complete their aquatic development. </p>
<p>The problem is that in many African countries, agricultural practices are <a href="https://www.sciencedirect.com/science/article/pii/S0306919216303906?via%3Dihub">more common</a> on gently sloping shorelines. This means there’s more space available for malaria mosquitoes to breed.</p>
<h2>So what can be done?</h2>
<p>The world is striving to eliminate malaria. The World Health Organisation has <a href="https://www.who.int/malaria/areas/global_targets/en/">set a target</a> of reducing global malaria cases and mortality rates by at least 90% by 2030. But dam reservoirs will continue to be focal points for malaria transmission in sub-Saharan Africa – a region where <a href="https://www.afro.who.int/health-topics/malaria">90%</a> of the global malaria burden exists. </p>
<p>More rigorous impact prediction assessments must be done at the planning stages to determine the likely malaria impacts when considering new dams. Greater consideration must be given to the slopes of reservoir shores and the implications for malaria. </p>
<p>In short, the slope of reservoir shores should be considered when siting a new dam. Water managers and health managers need to collaborate much more closely to alleviate malaria risks.</p><img src="https://counter.theconversation.com/content/123475/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Solomon Kibret 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>Water is crucial to the spread of malaria because mosquitoes breed and lay their eggs in or near bodies of water.Solomon Kibret, Researcher, University of California, IrvineLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1222942019-09-16T12:02:24Z2019-09-16T12:02:24ZThere’s a way for modern medicine to cure diseases even when the treatments aren’t profitable<figure><img src="https://images.theconversation.com/files/291774/original/file-20190910-190035-le6o0h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Millions of young children get malaria. These two got it in 2010.</span> <span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Congo-South-Africa-Malaria-Vaccine/3260199e339e4cb893eca38e5580e2e8/1/0">AP Photo/Schalk van Zuydam </a></span></figcaption></figure><p>Strides in medicine have contributed to a <a href="https://ourworldindata.org/grapher/life-expectancy-globally-since-1770">dramatic increase in life expectancy</a> over the last century. Diseases like <a href="https://time.com/4585537/world-aids-day-hiv/">HIV</a> and <a href="https://report.nih.gov/nihfactsheets/viewfactsheet.aspx?csid=76">cervical cancer</a> that were essentially death sentences as recently as 30 years ago can now be managed with access to prescription drugs and surgical procedures.</p>
<p>Yet previously unknown or undiagnosed diseases and conditions continue to appear. And there are few to no effective treatments for many diseases and conditions.</p>
<p>Especially when the people susceptible to those illnesses tend to be <a href="https://www.clinipace.com/low-income-countries-severely-affected-infectious-diseases/">low-income</a>, the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3327542/">costly</a> fight to find cures and develop vaccines for those diseases are unlikely to be <a href="https://www.bloomberg.com/news/articles/2019-05-03/antibiotics-aren-t-profitable-enough-for-big-pharma-to-make-more">profitable</a>.</p>
<p>That is why I believe nonprofits have a vital role to play in funding these endeavors.</p>
<h2>No ‘moonshot’</h2>
<p>The research I have engaged in for most of my career as a <a href="https://scholar.google.com/citations?user=N4_3qVkAAAAJ&hl=en&oi=sra">medicinal chemist</a> has been focused on drug discovery. Much of these efforts have been aimed at treating <a href="https://www.exelixis.com/cabozantinib-development-program/">cancer</a> and <a href="https://ir.exelixis.com/news-releases/news-release-details/exelixis-collaborator-daiichi-sankyo-launches-minnebror">cardiovascular disease</a>.</p>
<p>More innovation is required for the development of new drugs that can, to name two examples, keep <a href="https://doi.org/10.1377/hlthaff.28.4.949">malaria</a> and <a href="https://dx.doi.org/10.1016%2Fj.pt.2018.07.007">dengue fever</a> at bay.</p>
<p>Unfortunately, despite the desperate need for drugs for other illnesses that mostly afflict the poor, most drugmakers are not <a href="https://www.nationalgeographic.com/science/phenomena/2015/05/23/oneill-amr-3/">pursuing new methods for treating them</a>. That is, there is no “<a href="https://www.cancer.gov/research/key-initiatives/moonshot-cancer-initiative">moonshot</a>” aimed at curing and preventing these illnesses being funded by the private sector.</p>
<p>And while federal agencies like the National Institutes of Health do provide funding for the study of <a href="https://www.hhs.gov/about/budget/fy2018/budget-in-brief/nih/index.html">infectious diseases and neurological disorders</a>, neither have adequate funding. </p>
<p>The problem is that <a href="https://www.medpagetoday.com/blogs/revolutionandrevelation/72407">private companies are largely obligated to maximize their profits</a> no matter what they produce. It therefore seems unreasonable to expect drug companies to work in areas that they suspect will not earn any money in the long run, if ever.</p>
<h2>$1.4 billion</h2>
<p>Let’s say the president of Pfizer were to announce tomorrow that the company is going to invest heavily in <a href="https://www.theguardian.com/world/2019/aug/23/malaria-will-not-be-eradicated-in-near-future-warns-who">eradicating malaria</a>. They would likely be nominated for the Nobel Peace Prize. However, the company might immediately start looking for a new top executive since eradicating malaria would easily cost Pfizer more than it could possibly recoup in sales. </p>
<p>A 2016 report by the <a href="https://doi.org/10.1016/j.jhealeco.2016.01.012">Tufts Center for the Study of Drug Development</a> estimated the cost of developing an FDA-approved prescription drug is US$1.4 billion. Production, shipping or any type of sales cost even more.</p>
<p>Meanwhile, those at the greatest risk of contracting malaria live in countries where the <a href="http://global-growing.org/en/content/fact-7-about-three-quarters-african-population-live-less-2-half-population-less-125-day">average annual income can be less than $1,000</a>. The prospects of being able to recover even a small fraction of that investment are <a href="https://health-e.org.za/2001/10/26/no-new-drugs-for-unprofitable-diseases-of-developing-world/">extremely slim</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/291644/original/file-20190909-109915-18lt48x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/291644/original/file-20190909-109915-18lt48x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/291644/original/file-20190909-109915-18lt48x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/291644/original/file-20190909-109915-18lt48x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/291644/original/file-20190909-109915-18lt48x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/291644/original/file-20190909-109915-18lt48x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/291644/original/file-20190909-109915-18lt48x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/291644/original/file-20190909-109915-18lt48x.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">Bringing a new drug to market from experimentation through marketing costs a small fortune.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/flask-scientist-hand-dropping-chemical-liquid-457937065?src=1-SETlpvTrCJ8KDprGS8uQ-1-34">totojang1977/Shutterstock.com</a></span>
</figcaption>
</figure>
<h2>Superbugs</h2>
<p>Before you dismiss this as a problem unlikely to affect your own well-being, consider the health risks posed by <a href="https://www.cdc.gov/features/antibiotic-resistance-global/index.html">antibiotic resistance</a>.</p>
<p>The development of bacterial resistance to common drugs like <a href="https://www.drugs.com/article/antibiotic-resistance.html">amoxicillin</a>, <a href="https://www.webmd.com/sexual-conditions/antibiotic-resistant-std-faq">azithromycin</a> and other similar drugs has given rise to the discovery of other drugs such as <a href="https://www.mdedge.com/ccjm/article/95526/drug-therapy/vancomycin-50-something-year-old-antibiotic-we-still-dont-understand">vancomycin</a> and <a href="https://www.britannica.com/science/methicillin">methicillin</a>. However, new strains of bacteria have come along that are <a href="https://www.the-hospitalist.org/hospitalist/article/121560/antimicrobial-resistant-infections/superbug-infections-rise-no-antibiotic">resistant to even these last lines of defense</a>. </p>
<p>Modern medicine has no known treatments against these so-called “superbugs.”</p>
<p>Absent new drugs to treat such infections, a person who gets a scratch that becomes infected could be at risk of dying. </p>
<p>With that in mind, there is a clear need for new antibiotic drug discovery. Yet <a href="https://www.businessinsider.com/major-pharmaceutical-companies-dropping-antibiotic-projects-superbugs-2018-7">virtually all drugmakers have moved away from this line of business</a> for one obvious reason.</p>
<p>If a new drug were identified tomorrow, it would obviously be held out as the new <a href="https://www.healthcaredive.com/news/without-more-stewardship-superbugs-could-kill-thousands-more-americans-ann/541832/">last line of resistance</a> for the treatment of bacterial infections. How could a company justify spending the requisite $1.4 billion to develop a drug that would only be used as a drug of last resort?</p>
<p>If, say, 1,000 patients needed the drug in a given year, could a company realistically expect each patient over 10 years to pay $140,000 just to recover the initial cost of the discovery? Of course not. But it might make sense for nonprofits to do this if that’s their mission.</p>
<h2>Promising examples</h2>
<p>There are nonprofits who engage in drug discovery for these neglected diseases. One good example is <a href="https://www.mmv.org/">Medicines for Malaria Venture</a>, a group of scientists based in Switzerland dedicated to reducing the burden of malaria on a global scale. </p>
<p><a href="https://www.gatesfoundation.org/">The Bill and Melinda Gates Foundation</a>, <a href="https://www.oneworldhealth.com/">OneWorld Health</a>, the <a href="https://www.newtbdrugs.org/">Working Group on New Tuberculosis Drugs</a> and the <a href="https://www.milkeninstitute.org/centers/center-for-public-health">Milken Institute Center for Public Health</a> are among the best-known organizations working to realize these important goals <a href="https://www.mmv.org/partnering/our-donors/current-donors">without being subjected to stockholder pressure</a>.</p>
<p>These efforts have given rise to <a href="https://www.mmv.org/research-development/mmv-supported-projects">nearly a dozen new approved drugs to treat malaria</a>, and they have made progress toward creating vaccines that might stem the spread of diseases like <a href="https://www.who.int/csr/resources/publications/ebola/ebola-ring-vaccination-results-12-april-2019.pdf">Ebola</a> and <a href="https://www.nih.gov/news-events/news-releases/nih-begins-clinical-trial-live-attenuated-zika-vaccine">Zika</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/291643/original/file-20190909-109927-1vxzs3z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/291643/original/file-20190909-109927-1vxzs3z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/291643/original/file-20190909-109927-1vxzs3z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/291643/original/file-20190909-109927-1vxzs3z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/291643/original/file-20190909-109927-1vxzs3z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/291643/original/file-20190909-109927-1vxzs3z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/291643/original/file-20190909-109927-1vxzs3z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/291643/original/file-20190909-109927-1vxzs3z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=471&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The bacteria that causes tuberculosis.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/bacteria-mycobacterium-tuberculosis-causative-agent-3d-1013219203?src=qmHc3gUU1FUp62X5iZ4ujw-1-1">Kateryna Kon/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>The <a href="https://www.tballiance.org/">TB Alliance</a> is an international nonprofit dedicated to the discovery, development and delivery of better, faster-acting and affordable tuberculosis drugs that are available to <a href="https://www.cdc.gov/tb/statistics/default.htm">those who need them</a>.</p>
<p>With support from the <a href="https://www.tballiance.org/about/donors">Gates Foundation</a> and government agencies from around the world, the alliance gained FDA approval for <a href="https://www.fda.gov/news-events/press-announcements/fda-approves-new-drug-treatment-resistant-forms-tuberculosis-affects-lungs">pretomanid</a>, its new drug that can treat multidrug-resistant TB, which an estimated <a href="https://www.who.int/tb/areas-of-work/drug-resistant-tb/en/">600,000 people develop every year</a>.</p>
<p>What I found to be especially noteworthy is that the alliance facilitated and funded the efforts that resulted in a new lifesaving treatment without creating its own lab. Instead, it coordinated the efforts of other researchers already conducting TB investigations in many countries. </p>
<p>The continued support by government agencies, private donors and nonprofits of these ventures could prove paramount to the survival of the human species. While their continued funding is clearly needed to provide these critical medicines, all of us are fortunate to have organizations such as this working for the betterment of mankind.</p>
<p>[ <em><a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=expertise">Expertise in your inbox. Sign up for The Conversation’s newsletter and get a digest of academic takes on today’s news, every day.</a></em> ]</p><img src="https://counter.theconversation.com/content/122294/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>James Leahy owns shares of stock in a variety of pharmaceutical companies, including Exelixis, where he worked for 14 years. His research is funded in part by funding agencies such as the National Institutes of Health and the National Science Foundation.</span></em></p>There’s a big market for new treatments for TB, malaria and other ailments. But most of these diseases afflict low-income people unable to pay for medicine.James Leahy, Professor of Chemistry; Interim Chair of the Chemistry Department, University of South FloridaLicensed 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/1122122019-02-25T19:09:03Z2019-02-25T19:09:03ZExplainer: what is Murray Valley encephalitis virus?<p>Western Australian health authorities recently <a href="https://ww2.health.wa.gov.au/Media-releases/2019/Murray-Valley-encephalitis-warning-for-Kimberley">issued warnings</a> about Murray Valley encephalitis, a serious disease that can spread by the bite of an infected mosquito and cause inflammation of the brain.</p>
<p>Thankfully, no human cases have been reported this wet season. The virus that causes the disease was detected in chickens in the Kimberley region. These “sentinel chickens” act as an early warning system for potential disease outbreaks.</p>
<h2>What is Murray Valley encephalitis virus?</h2>
<p>Murray Valley encephalitis virus is named after the Murray Valley in southeastern Australia. The virus was first isolated from patients who died from encephalitis during an outbreak there in 1951.</p>
<p>The virus is a member of the Flavivirus family and is closely related to <a href="https://theconversation.com/what-is-japanese-encephalitis-virus-and-how-can-i-avoid-it-when-i-travel-106775">Japanese encephalitis virus</a>, a major cause of encephalitis in Asia. </p>
<p>Murray Valley encephalitis virus is found in northern Australia circulating between mosquitoes, especially <em>Culex annulirostris</em>, and water birds. Occasionally the virus spreads to southern regions, as mosquitoes come into contact with infected birds that have migrated from northern regions.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/after-the-floods-come-the-mosquitoes-but-the-disease-risk-is-more-difficult-to-predict-111173">After the floods come the mosquitoes – but the disease risk is more difficult to predict</a>
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<h2>How serious is the illness?</h2>
<p>After being transmitted by an infected mosquito, the virus incubates for around two weeks. </p>
<p>Most people infected don’t develop symptoms. But, if you’re unlucky, you could develop <a href="https://www.mja.com.au/journal/2012/196/5/murray-valley-encephalitis-review-clinical-features-diagnosis-and-treatment">symptoms</a> ranging from fever and headache to paralysis, encephalitis and coma. </p>
<p>Around 40% of people who develop symptoms won’t fully recover and about 25% die. Generally, one or two human cases are reported in Australia per year.</p>
<p>Since the 1950s, there have been <a href="https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0002656">sporadic outbreaks</a> of Murray Valley encephalitis, most notably in 1974 and 2011. The 1974 outbreak was Australia-wide, resulting in 58 cases and 12 deaths. </p>
<p>It’s likely the virus has been causing disease since at least the early 1900s when epidemics of encephalitis were attributed to a mysterious illness called <a href="https://www.sciencedirect.com/science/article/pii/037811359500074K">Australian X disease</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/260097/original/file-20190221-148517-1h3kl53.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/260097/original/file-20190221-148517-1h3kl53.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/260097/original/file-20190221-148517-1h3kl53.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/260097/original/file-20190221-148517-1h3kl53.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/260097/original/file-20190221-148517-1h3kl53.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/260097/original/file-20190221-148517-1h3kl53.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/260097/original/file-20190221-148517-1h3kl53.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">Traditional monitoring of mosquito-borne diseases relies on the collection of mosquitoes using specially designed traps baited with carbon dioxide.</span>
<span class="attribution"><span class="source">Cameron Webb</span></span>
</figcaption>
</figure>
<h2>Early warning system</h2>
<p>Given the severity of Murray Valley encephalitis, health authorities rely on <a href="https://parasitesandvectors.biomedcentral.com/articles/10.1186/s13071-018-2901-x">early warning systems</a> to guide their responses. </p>
<p>One of the most valuable surveillance tools to date have been chooks because the virus circulates between birds and mosquitoes. Flocks of chickens are placed in areas with past evidence of virus circulation and where mosquitoes are buzzing about.</p>
<p>Chickens are highly susceptible to infection so blood samples are routinely taken and analysed to determine evidence of virus infection. If a chicken tests positive, the virus has been active in an area.</p>
<p>The good news is that even if the chickens have been bitten, they don’t get sick.</p>
<p>Mosquitoes can also be collected in the field using <a href="https://theconversation.com/the-worst-year-for-mosquitoes-ever-heres-how-we-find-out-68433">a variety of traps</a>. Captured mosquitoes are counted, grouped by species and tested to see if they’re carrying the virus. </p>
<p>This method is very sensitive: it can identify as little as one infected mosquito in a group of 1,000. But processing is labour-intensive. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-australian-wildlife-spread-and-suppress-ross-river-virus-107267">How Australian wildlife spread and suppress Ross River virus</a>
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</em>
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<hr>
<h2>How can technology help track the virus?</h2>
<p>Novel approaches are allowing scientists to more effectively detect viruses in mosquito populations. </p>
<p>Mosquitoes feed on more than just blood. They also need a sugar fix from time to time, usually plant nectar. When they feed on sugary substances, <a href="https://academic.oup.com/jme/article-abstract/44/5/845/973141?redirectedFrom=fulltext">they eject small amounts of virus in their saliva</a>. </p>
<p>This led researchers to develop traps that contain <a href="https://www.pnas.org/content/107/25/11255">special cards coated in honey</a>. When the mosquitoes feed on the cards, they spit out virus, which specific tests can then detect. </p>
<p>We are also investigating whether <a href="https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0006771">mosquito poo</a> could be used to enhance the sugar-based surveillance system. Mosquitoes spit only tiny amounts of virus, whereas they poo a lot (300 times more than they spit). </p>
<p>This mosquito poo can contain a treasure trove of genetic material, <a href="https://www.nature.com/articles/srep24885">including viruses</a>. But we’re still working out the best way to collect the poo. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/260136/original/file-20190221-195883-zv7d4a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/260136/original/file-20190221-195883-zv7d4a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=386&fit=crop&dpr=1 600w, https://images.theconversation.com/files/260136/original/file-20190221-195883-zv7d4a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=386&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/260136/original/file-20190221-195883-zv7d4a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=386&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/260136/original/file-20190221-195883-zv7d4a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=485&fit=crop&dpr=1 754w, https://images.theconversation.com/files/260136/original/file-20190221-195883-zv7d4a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=485&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/260136/original/file-20190221-195883-zv7d4a.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">Mosquito poo, shown here after mosquitoes have fed on coloured honey, can be used to detect viruses like Murray Valley encephalitis.</span>
<span class="attribution"><span class="source">Dagmar Meyer</span></span>
</figcaption>
</figure>
<h2>Staying safe from Murray Valley encephalitis</h2>
<p>There is no vaccine or specific treatment for the virus. Avoiding mosquito bites is the only way to protect yourself from the virus. You can do this by:</p>
<ul>
<li><p>wearing protective clothing when outdoors</p></li>
<li><p>avoiding being outdoors when the mosquitoes that transmit the virus are most active (dawn and dusk)</p></li>
<li><p>using <a href="https://theconversation.com/the-best-and-worst-ways-to-beat-mosquito-bites-70274">repellents</a>, mosquito coils, insect screens and mosquito nets</p></li>
<li><p>following public health advisories for your area.</p></li>
</ul>
<p>The virus is very rare and your chances of contracting the disease are extremely low, but not being bitten is the best defence.</p><img src="https://counter.theconversation.com/content/112212/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ana Ramírez is supported by a doctoral scholarship granted by the Australian Institute of Tropical Health and Medicine, James Cook University. </span></em></p><p class="fine-print"><em><span>Andrew van den Hurk has received funding from local, state and federal agencies to study the ecology of mosquito-borne pathogens, and their surveillance and control. He is an employee of the Department of Health, Queensland Government.</span></em></p><p class="fine-print"><em><span>Cameron Webb and the Department of Medical Entomology, NSW Health Pathology and University of Sydney, have been engaged by a wide range of insect repellent and insecticide manufacturers to provide testing of products and provide expert advice on the biology of medically important insects. 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>Scott Ritchie receives funding from the National Health and Medical Research Council, Menzies HOT NORTH Programme, and Verily Life Sciences to study the ecology of mosquitoes and how to trap them.</span></em></p>Murray Valley encephalitis virus is a rare but potentially fatal mosquito-borne virus. Here’s what you need to know about it.Ana Ramírez, PhD candidate, James Cook UniversityAndrew van den Hurk, Medical Entomologist, The University of QueenslandCameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of SydneyScott Ritchie, Professorial Research Fellow, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1111732019-02-07T05:53:22Z2019-02-07T05:53:22ZAfter the floods come the mosquitoes – but the disease risk is more difficult to predict<p>We’re often warned to avoid mosquito bites after major flooding events. With more water around, there are likely to be more mosquitoes. </p>
<p>As flood waters recede around Townsville and clean-up efforts continue, the local population will be faced with this prospect over the coming weeks.</p>
<p>But whether a greater number of mosquitoes is likely to lead to an outbreak of mosquito-borne disease is tricky to predict. It depends on a number of factors, including the fate of other wildlife following a disaster of this kind.</p>
<h2>Mozzies need water</h2>
<p>Mosquitoes lay their eggs in and around water bodies. In the initial stages, baby mosquitoes (or “wrigglers”) need the water to complete their development. During the warmer months, it doesn’t take much longer than a week before they are grown and fly off looking for blood. </p>
<p>So the more water, the more mosquito eggs are laid, and the more mosquitoes end up buzzing about. </p>
<p>But outbreaks of disease carried by mosquitoes are dependent on more than just their presence. Mosquitoes rarely emerge from wetlands infected with pathogens. They typically need to pick them up from <a href="https://theconversation.com/how-australian-wildlife-spread-and-suppress-ross-river-virus-107267">biting local wildlife</a>, such as birds or mammals, before they can spread disease to people.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-worst-year-for-mosquitoes-ever-heres-how-we-find-out-68433">The worst year for mosquitoes ever? Here's how we find out</a>
</strong>
</em>
</p>
<hr>
<h2>Mosquitoes and extreme weather events</h2>
<p>Historically, major inland flooding events have triggered <a href="https://cameronwebb.wordpress.com/2016/10/06/do-outbreaks-of-mosquito-borne-disease-always-follow-floods/">significant outbreaks of mosquito-borne disease</a> in Australia. These <a href="https://academic.oup.com/trstmh/article/111/6/248/4554990">outbreaks</a> have included epidemics of the potentially fatal Murray Valley encephalitis virus. In recent decades, Ross River virus has more commonly been the culprit.</p>
<p>A focal point of the current floods is the Ross River, which runs through Townsville. The <a href="https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1005070">Ross River virus</a> was first identified from mosquitoes collected along this waterway. The disease it causes, known as Ross River fever, is diagnosed in <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC89008/">around 5,000 Australians every year</a>. The disease isn’t fatal but it can be seriously debilitating.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/257600/original/file-20190206-174883-18eppdz.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/257600/original/file-20190206-174883-18eppdz.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/257600/original/file-20190206-174883-18eppdz.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/257600/original/file-20190206-174883-18eppdz.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/257600/original/file-20190206-174883-18eppdz.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/257600/original/file-20190206-174883-18eppdz.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/257600/original/file-20190206-174883-18eppdz.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">Following substantial rainfall, mosquito populations can dramatically increase. Carbon dioxide baited light traps are used by local authorities to monitor changes in mosquito populations.</span>
<span class="attribution"><span class="source">Cameron Webb (NSW Health Pathology)</span></span>
</figcaption>
</figure>
<p>In recent years, major outbreaks of Ross River virus have occurred throughout the country. Above average rainfall is likely a driving factor as it boosts both the abundance and diversity of local mosquitoes.</p>
<p>Flooding across Victoria over the 2016-2017 summer produced <a href="https://www.abc.net.au/news/2017-02-09/ross-river-virus-cases-spike-victoria-nsw/8255280">exceptional increases in mosquitoes</a> and resulted in the state’s largest outbreak of Ross River virus. There were almost <a href="http://www9.health.gov.au/cda/source/cda-index.cfm">1,700 cases</a> of Ross River virus disease reported there in 2017 compared to an average of around 300 cases annually over the previous 20 years.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-is-ross-river-virus-24630">Explainer: what is Ross River virus?</a>
</strong>
</em>
</p>
<hr>
<p>Despite plagues of mosquitoes taking advantage of flood waters, outbreaks of disease don’t always follow. </p>
<p>Flooding resulting from hurricanes in North America has been associated with increased mosquito populations. After Hurricane Katrina hit Louisiana and Mississippi in 2005, there was <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2828079/">no evidence</a> of increased mosquito-borne disease. The impact of wind and rain is likely to have adversely impacted local mosquitoes and wildlife, subsequently reducing disease outbreak risk.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/257643/original/file-20190207-174873-x72kvj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/257643/original/file-20190207-174873-x72kvj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/257643/original/file-20190207-174873-x72kvj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/257643/original/file-20190207-174873-x72kvj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/257643/original/file-20190207-174873-x72kvj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/257643/original/file-20190207-174873-x72kvj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/257643/original/file-20190207-174873-x72kvj.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">Applying insect repellent is worthwhile even if the risk of mosquito-borne disease isn’t known.</span>
<span class="attribution"><span class="source">From shutterstock.com</span></span>
</figcaption>
</figure>
<p><a href="https://academic.oup.com/jme/article/51/6/1097/861519">Australian studies</a> suggest there’s not always an association between flooding and Ross River virus outbreaks. Outbreaks can be triggered by flooding, but this is not always the case. Where and when the flooding occurs probably plays a major role in determining the likelihood of an outbreak.</p>
<p>The <a href="https://www.tandfonline.com/doi/abs/10.1080/23737867.2017.1359697">difficulty in predicting</a> outbreaks of Ross River virus disease is that there can be <a href="https://parasitesandvectors.biomedcentral.com/articles/10.1186/s13071-018-2776-x">complex biological, environmental and climatic drivers</a> at work. Conditions may be conducive for large mosquito populations, but if the extreme weather events have displaced (or decimated) local wildlife populations, there may be a decreased chance of outbreak. </p>
<p>This may be why historically significant outbreaks of mosquito-borne disease have occurred in inland regions. Water can persist in these regions for longer than coastal areas. This provides opportunities not only for multiple mosquito generations, but also for increasing <a href="https://www.sciencedirect.com/science/article/pii/S0006320701002683">populations of water birds</a>. These birds can be important <a href="https://www.liebertpub.com/doi/abs/10.1089/vbz.2008.0040">carriers of pathogens</a> such as the Murray Valley encephalitis virus.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/giant-mosquitoes-flourish-in-floodwaters-that-hurricanes-leave-behind-104350">Giant mosquitoes flourish in floodwaters that hurricanes leave behind</a>
</strong>
</em>
</p>
<hr>
<p>In coastal regions like Townsville, where the main concern would be Ross River virus, flood waters may displace the wildlife that carry the virus, such as kangaroos and wallabies. For that reason, the flood waters may actually reduce the initial risk of outbreak.</p>
<h2>Protect yourself</h2>
<p>There is <a href="https://parasitesandvectors.biomedcentral.com/articles/10.1186/s13071-018-2733-8">still much to learn</a> about the ecology of wildlife and their role in driving outbreaks of disease. And with a fear of <a href="https://www.abc.net.au/news/2019-02-06/could-climate-change-make-australia-uninsurable/10783490">more frequent and severe extreme weather events</a> in the future, it’s an important area of research.</p>
<p>Although it remains difficult to predict the likelihood of a disease outbreak, there are steps that can be taken to avoid mosquito bites. This will be useful even if just to reduce the nuisance of sustaining bites.</p>
<p>Cover up with long-sleeved shirts and long pants for a physical barrier against mosquito bites and use topical insect repellents containing <a href="https://theconversation.com/chemical-or-natural-whats-the-best-way-to-repel-mozzies-36879">DEET, picaridin, or oil of lemon eucalyptus</a>. Be sure to apply an even coat on all exposed areas of skin for the longest lasting protection.</p><img src="https://counter.theconversation.com/content/111173/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cameron Webb and the Department of Medical Entomology, NSW Health Pathology and University of Sydney, have been engaged by a wide range of insect repellent and insecticide manufacturers to provide testing of products and provide expert advice on the biology of medically important insects. 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 more water, the more mosquito eggs are laid, and the more mosquitoes end up buzzing about. But to spread disease to people, they first need to bite infected wildlife.Cameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/926112018-03-07T19:25:00Z2018-03-07T19:25:00ZThe buzz from your smartphone won’t stop mosquito bites<p>Forget a peaceful night’s sleep. The whine of a lone mosquito circling your bedroom can be incredibly frustrating. They’re not just the <a href="http://www.who.int/mediacentre/factsheets/fs094/en/">deadliest animals on the planet</a>, they could be the most annoying!</p>
<p>Often various products or apps claim special sounds can stop mosquitos from buzzing. But the science doesn’t back up these claims. And tuning into mosquitoes’ murmurings might even help us prevent disease.</p>
<h2>Why do mosquitoes make that sound?</h2>
<p>All mosquitoes make sound. The mosquitoes you hear are usually the ones a little less decisive about biting. Those more ready to bite will come in, land, suck your blood and fly off before you’ve noticed them. </p>
<p>Those occasionally annoying tones produced by mosquitoes come from the <a href="https://www.sciencenews.org/article/mosquito-flight-unlike-any-other-insect">beating of their wings</a>. The sounds can be wide-ranging and vary between males and females. Each mosquito has its own musical “fingerprint” but its not just the noisy by-product of flight, the tones produced by mosquitoes can be used for communication. Romantic communication.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-can-i-eat-to-stop-mosquitoes-biting-me-87178">What can I eat to stop mosquitoes biting me?</a>
</strong>
</em>
</p>
<hr>
<p>Male and female mosquitoes of some species have been documented responding to the wing beat frequencies of each other in a “<a href="https://www.sciencedirect.com/science/article/pii/S0960982209009816">mating duet</a>”. In a phenomenon known as “harmonic convergence” the mosquitoes change the frequency of their wing beats in response to each other. This <a href="https://www.sciencedirect.com/science/article/pii/S0960982206016368">helps identify potential mates</a> and make an <a href="http://science.sciencemag.org/content/323/5917/1077">assessment of the quality</a> of the potential mate based on the quality of their “song”.</p>
<p>This romantic sing-along has been reported in a range of mosquitoes involved in the transmission of <a href="http://science.sciencemag.org/content/323/5917/1077">dengue</a> and <a href="https://www.sciencedirect.com/science/article/pii/S0960982209020557">malaria</a> pathogens. So an understanding of how mosquitoes make and respond to sound could provide better mosquito surveillance or control strategies.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/208739/original/file-20180303-65522-1f8ega5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/208739/original/file-20180303-65522-1f8ega5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/208739/original/file-20180303-65522-1f8ega5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/208739/original/file-20180303-65522-1f8ega5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/208739/original/file-20180303-65522-1f8ega5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/208739/original/file-20180303-65522-1f8ega5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/208739/original/file-20180303-65522-1f8ega5.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">This is the mosquito buzzing in your ear, the brown house mosquito (Culex quinquefasciatus) most commonly comes inside and will buzz about your bedroom at night.</span>
<span class="attribution"><span class="source">Stephen Doggett (NSW Health Pathology)</span></span>
</figcaption>
</figure>
<p><audio preload="metadata" controls="controls" data-duration="131" data-image="" data-title="Sounds of the Brown House Mosquito (_Culex quinquefasciatus_)" data-size="2111946" data-source="Cameron Webb" data-source-url="https://soundcloud.com/seaworthy/culex-quinquefasciatus" data-license="Author provided (no reuse)" data-license-url="">
<source src="https://cdn.theconversation.com/audio/1073/cameronwebb-mosquitoesounds-culexquinquefasciatus-feb2018.mp3" type="audio/mpeg">
</audio>
<div class="audio-player-caption">
Sounds of the Brown House Mosquito (<em>Culex quinquefasciatus</em>)
<span class="attribution"><a class="source" rel="nofollow" href="https://soundcloud.com/seaworthy/culex-quinquefasciatus">Cameron Webb</a>, <span class="license">Author provided (no reuse)</span><span class="download"><span>2.01 MB</span> <a target="_blank" href="https://cdn.theconversation.com/audio/1073/cameronwebb-mosquitoesounds-culexquinquefasciatus-feb2018.mp3">(download)</a></span></span>
</div></p>
<h2>Sounds to keep mosquitoes away</h2>
<p>There is a long history of entrepreneurs marketing various sound-producing gadgets to repel mosquitoes. The sounds broadcast typically covered a range of frequencies, some even the sounds of mosquito predators (such as the wing beat frequencies of dragonflies). There was <a href="http://www.bbc.com/news/magazine-20669080">little scientific evidence</a> they worked.</p>
<p>There are now dozens of “mosquito repellent” apps available online for your smartphone. The sounds may now be available with a swipe of the finger, rather than a flick of a switch, but the general sale pitch remains the same, silence the mosquito bites with sound.</p>
<p>It’s all wishful thinking. There is no evidence sound emitting devices can stop mosquitoes biting. A review of field testing showed <a href="http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD005434.pub2/full">no protection was provided</a>. Similarly, laboratory studies <a href="http://europepmc.org/abstract/med/2906666">failed to show any bite prevention</a>.</p>
<p>Studies have even demonstrated these sound-emitting devices actually increase mosquito bites by the <a href="https://www.sciencedirect.com/science/article/pii/S0001706X12003452">Asian Tiger Mosquito</a> and <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1948-7134.2010.00061.x/full">Yellow Fever mosquito</a>.</p>
<p>There’s no reason to think smartphone apps are <a href="http://www.independent.co.uk/travel/news-and-advice/can-you-repel-mosquitoes-with-an-app-a6981121.html">going to perform any better</a> than any of the other gimmicks that have come and gone from supermarket shelves over the decades. If they cannot stop mosquito bites, they won’t <a href="http://www.scielo.br/scielo.php?pid=S1519-566X2001000300030&script=sci_arttext">prevent mosquito-borne disease</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/208782/original/file-20180304-65516-tl91zz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/208782/original/file-20180304-65516-tl91zz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=373&fit=crop&dpr=1 600w, https://images.theconversation.com/files/208782/original/file-20180304-65516-tl91zz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=373&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/208782/original/file-20180304-65516-tl91zz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=373&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/208782/original/file-20180304-65516-tl91zz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=469&fit=crop&dpr=1 754w, https://images.theconversation.com/files/208782/original/file-20180304-65516-tl91zz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=469&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/208782/original/file-20180304-65516-tl91zz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=469&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">There are dozens of apps available for your smartphone but there is little evidence they provide any genuine protection from biting mosquitoes.</span>
<span class="attribution"><span class="source">Cameron Webb (NSW Health Pathology)</span></span>
</figcaption>
</figure>
<h2>Calling all mosquitoes!</h2>
<p>Sound may not be helping stop mosquito bites but it could still be useful in managing mosquito-borne disease outbreaks.</p>
<p>Mosquito traps used by scientists and health authorities around the world focus on <a href="https://theconversation.com/the-worst-year-for-mosquitoes-ever-heres-how-we-find-out-68433">attracting female mosquitoes</a> as they search for blood or a place to lay eggs. There’s generally not been much interest in males.</p>
<p>Exploiting the attraction of male mosquitoes to the sounds of females is being tested in new surveillance technologies. Baiting mosquito traps with sound devices replicating the flight tone of female <em>Aedes aegypti</em> mosquitoes collected <a href="https://phys.org/news/2015-10-male-mosquitoes-lured-female-wing-beats.html">approximately twice as many male mosquitoes</a> compared to traps without sound. </p>
<p>Female mosquitoes didn’t respond to sound but when biosecurity surveillance relies on picking up as many mosquitoes as possible, the additional male mosquitoes collected increases the likelihood of detecting the arrival of exotic mosquitoes.</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>The “acoustic fingerprint” of mosquitoes may be also be key to new mosquito traps that not only catch the mosquitoes, but <a href="https://medium.com/the-physics-arxiv-blog/entomologists-have-never-been-able-to-identify-flying-insects-automatically-until-now-ee4d93067443">can identify them too</a>. Studies have investigated how wing beat frequencies can be used to identify the mosquito species and <a href="https://www.sciencedirect.com/science/article/pii/S0168169915002471">even tell if they’re male or female</a>.</p>
<p>There is little doubt <a href="https://news.microsoft.com/transform/videos/technology-turns-mosquitoes-into-allies-instead-of-enemies-in-the-fight-against-deadly-viruses/#sm.000006ip5r949vdw2rexdyfudjj3x">traps of this nature</a> will play a critical role in providing an early warning of future mosquito-borne disease outbreaks.</p>
<p>For now though, if it’s the buzz of bedroom mosquitoes keeping you awake, there are some easy solutions. Screening your windows will keep them out. Using insecticides will help but are not always necessary.</p>
<p>Switch on a ceiling or oscillating fan and the breeze will blow away the carbon dioxide you’re exhaling that’s attracting the mosquitoes. It will also make it just a little harder for the mosquito to circle your bed and buzz in your ears!</p><img src="https://counter.theconversation.com/content/92611/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>The sounds of mosquitoes may be annoying to many but tuning into their musical whines could help design new mosquito traps. Just don’t expect sounds from your smartphone to protect you from bites!Cameron Webb, Clinical Lecturer and Principal Hospital Scientist, South Western Sydney Local Health DistrictLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/802692017-07-16T19:56:40Z2017-07-16T19:56:40ZMozzies are evolving to beat insecticides – except in Australia<figure><img src="https://images.theconversation.com/files/178024/original/file-20170713-9462-16t5ncj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mosquitoes are the main vectors for dengue and zika. Insecticides are our best weapon against them. </span> <span class="attribution"><span class="source">Anja Jonsson/Flickr</span></span></figcaption></figure><p>Chemical pesticides have been used for many years to control insect populations and remain the most important method of managing diseases carried by pests, including mosquitoes. However, insects have fought back by evolving resistance to many pesticides. <a href="https://www.pesticideresistance.org/">There are now thousands of instances of evolved resistance</a>, which make some chemical classes completely ineffective.</p>
<p>The <em>Aedes</em> mosquito, largely responsible for the spread of viruses like dengue and zika, has globally developed <a href="http://unifeb.edu.br/uploads/arquivos/revista-cientifica/Toxicidade_aguda_de_inseticidas_e_espalhante_usados_no_controle_de_vetores.pdf">resistance to commonly used chemicals, including pyrethroids</a>. Pyrethroids are the most used insecticides in the world, which includes the control of dengue outbreaks and quarantine breaches at air and sea ports.</p>
<p>In Asia and the Americas, pyrethroid resistance in <em>Aedes</em> mosquitoes is now <a href="http://journal.tropika.net/scielo.php?script=sci_arttext&pid=s2078-86062010000100003&lng=en">widespread</a>. In Australia, our mosquitoes have not developed these defences and pyrethroids are still very effective.</p>
<p>The difference lies in our stringent and careful protocols for chemical use. As the global community fights zika and other mosquito-borne diseases, there are lessons to be learned from Australia’s success. </p>
<h2>Developing resistance</h2>
<p>Mosquitoes usually become resistant to pyrethroids through the <a href="http://www.mdpi.com/2075-4450/7/4/60">mutation of a sodium channel gene</a> that controls the movement of ions across cell membranes. Mutations in a single gene are enough to make mosquitoes almost completely resistant to the level of pyrethroids used in insecticides. </p>
<p>The mutations first arises in a population by chance, and are rare. However, they rapidly spread as resistant females breed. The more times a mosquito population is exposed to the same chemical, the more the natural selection process favours their impervious offspring.</p>
<p>Eventually, when many individuals in a population carry the resistance mutation, the chemical becomes ineffective. This can <a href="https://www.mosquitonets.com/blog/the-practice-of-fogging/">happen where insecticide “fogging” is common practice</a>. Overseas, fogging is sometimes undertaken across entire neighbourhoods, several times a month, <a href="http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0004551">despite concerns about its effectiveness</a> as well as <a href="http://www.todayonline.com/voices/widespread-fogging-may-do-more-harm-good">its environmental and health impacts</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/178025/original/file-20170713-10278-1tiyfhp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/178025/original/file-20170713-10278-1tiyfhp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=389&fit=crop&dpr=1 600w, https://images.theconversation.com/files/178025/original/file-20170713-10278-1tiyfhp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=389&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/178025/original/file-20170713-10278-1tiyfhp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=389&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/178025/original/file-20170713-10278-1tiyfhp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=489&fit=crop&dpr=1 754w, https://images.theconversation.com/files/178025/original/file-20170713-10278-1tiyfhp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=489&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/178025/original/file-20170713-10278-1tiyfhp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=489&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A pest exterminator carries out insecticide fogging in an apartment block in Singapore.</span>
<span class="attribution"><a class="source" href="http://one.aap.com.au/#/search/mosquitoes?q=%7B%22pageSize%22:25,%22pageNumber%22:2%7D">EPA, Wallace Woon/AAP</a></span>
</figcaption>
</figure>
<p>Once resistance develops, it can spread to non-resistant mosquito populations in other areas. Pest species, including mosquitoes, are often highly mobile because they fly or are carried passively (in vehicles, ships and planes) at any stage of their life cycle. Their mobility means mutations spread quickly, crossing borders and possibly seas. </p>
<h2>We can still control Australian mosquitoes</h2>
<p>Despite this, Australian populations of <em>Aedes</em> mosquitoes remain susceptible to pyrethroids. <em>Aedes aegypti</em> (the yellow fever mosquito) is the main disease-carrying mosquito in Australia. Its population is restricted to urban areas of northern Queensland, where dengue can occur. </p>
<p>Recent research found that <a href="https://academic.oup.com/jme/article-abstract/doi/10.1093/jme/tjx145/3964514/Pyrethroid-Susceptibility-Has-Been-Maintained-in?redirectedFrom=fulltext">all Australian populations of this species are still vulnerable to pyrethroids</a>. None of the hundreds of mosquitoes tested had any mutations in the sodium channel gene, despite the high incidence of such mutations in <a href="https://www.ncbi.nlm.nih.gov/pubmed/26463408">mosquito populations of South-East Asia</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/178027/original/file-20170713-19645-sqvtig.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/178027/original/file-20170713-19645-sqvtig.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=403&fit=crop&dpr=1 600w, https://images.theconversation.com/files/178027/original/file-20170713-19645-sqvtig.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=403&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/178027/original/file-20170713-19645-sqvtig.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=403&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/178027/original/file-20170713-19645-sqvtig.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=507&fit=crop&dpr=1 754w, https://images.theconversation.com/files/178027/original/file-20170713-19645-sqvtig.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=507&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/178027/original/file-20170713-19645-sqvtig.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=507&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A female <em>Aedes aegypti</em> mosquito during a feed.</span>
<span class="attribution"><a class="source" href="https://phil.cdc.gov/phil/details.asp?pid=9178">James Gathany, CDC Prof Frank Hadley Collins/Wikimedia</a></span>
</figcaption>
</figure>
<p>We believe these mosquitoes remain vulnerable to pyrethroids because in Australia pressure to select for resistance has been low. </p>
<p>Australia does not carry out routine fogging. If <a href="https://www.health.qld.gov.au/__data/assets/pdf_file/0022/444433/dengue-mgt-plan.pdf">dengue is detected in an area</a>, pyrethoids are used in highly regimented and limited fashion. Spraying is restricted to the insides of premises within selected house blocks, and then only for a short period. </p>
<p>Importantly, water-filled artificial containers, which can serve as a habitat for larvae, are treated with insect growth regulators, which do not select for the pyrethroid resistance mutations. </p>
<h2>Exporting resistance</h2>
<p>With chemical resistance growing around the world, it is more urgent than ever that we co-ordinate action to control and reduce risk of resistance. Unfortunately, no global guidelines exist to minimise the evolution of resistance in mosquitoes. </p>
<p>Adopting <a href="http://www.irac-online.org/about/resistance/management/">pesticide resistance management strategies</a> has proven to be effective against other pests – for example, the <a href="https://www.daf.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/integrated-pest-management/a-z-insect-pest-list/helicoverpa/insecticide-resistance">corn earworm</a> (<em>Helicoverpa armigera</em>). Guidelines include rotating different class of pesticides to deny pests the chance to develop resistance, and investing in non-chemical options such as natural predators of target pests.</p>
<p>Resistance management strategies are particularly critical for new pesticides that have different <a href="http://www.irac-online.org/modes-of-action/">modes of attack</a>, such as preventing juvenile insects from moulting, or attacking various chemical receptors. </p>
<p>To prolong the effectiveness of pesticides, we must develop these strategies before resistance begins to develop. North Queensland may be an example to the rest of the world on the best path forward.</p><img src="https://counter.theconversation.com/content/80269/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ary Hoffmann receives funding from the National Health and Medical Research Council, the Australian Research Council,
the Wellcome Trust, and the Grains Research and Development Corporation. </span></em></p><p class="fine-print"><em><span>Nancy Margaret Endersby-Harshman receives funding from the National Health and Medical Research Council. </span></em></p><p class="fine-print"><em><span>Scott Ritchie receives funding from the National Health and Medical Research Council, US Dept. of Defence, and USAid.</span></em></p>Australian mosquitoes, unlike their Asian and American counterparts, can still be controlled by insecticides like pyrethroids. What lessons are there for managing pesticide resistance in insects?Ary Hoffmann, Professor, School of BioSciences and Bio21 Institute, The University of MelbourneNancy Margaret Endersby-Harshman, Research fellow, The University of MelbourneScott Ritchie, Professorial Research Fellow, James Cook UniversityLicensed 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>
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<span class="caption">A Florida Keys Mosquito Control District research entomologist releasing <em>Wolbachia</em>-infected male mosquitoes in Key West, Florida, in April.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Modified-Mosquitoes/0ef1eb60fb234e628c7ce2c3fe5a9522/1/0">Beth Ranson/Florida Keys Mosquito Control District via AP</a></span>
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<p>The strategy relies on a phenomenon called <a href="https://doi.org/10.1073/pnas.0403853101">cytoplasmic incompatibility (CI)</a> to reduce mosquito populations. CI occurs when a male mosquito infected with <em>Wolbachia</em> mates with an uninfected female. Because <em>Wolbachia</em> is transmitted through the female egg, the offspring will be <em>Wolbachia</em>-free. But <em>Wolbachia</em> has already altered the father’s sperm DNA in a way that allows offspring to survive only if the fertilized egg has <em>Wolbachia</em>. Since the infected males will come in contact only with the naturally occurring <em>Wolbachia</em>-free population, their offspring will die during embryonic development – the eggs won’t hatch. </p>
<p>And unfortunately for the mosquitoes, females store sperm inside them to continuously fertilize their eggs. This means that the female mosquito’s first mate will be the father of all her offspring. So even if a female just mates again, once she’s partnered with a <em>Wolbachia</em>-infected male, all her offspring will not be viable.</p>
<p>The Florida Keys Mosquito District is not limiting its attack to <a href="http://keysmosquito.org/control-methods/">just one approach</a>. Beyond <em>Wolbachia</em> and more traditional strategies, they’re also partnering with <a href="http://www.oxitec.com">Oxitec</a>, a genetic engineering company. Like MosquitoMate, Oxitec also releases male mosquitoes. But, in place of <em>Wolbachia</em>, Oxitec genetically modifies its mosquito to <a href="http://www.oxitec.com/our-solution/technology/">contain a self-limiting gene that causes offspring to die</a>.</p>
<p>The goal remains the same: Release males into the environment that will mate with females and cause all offspring to die, eventually leading to a mosquito population crash.</p>
<h2>Male and female strategies share one goal</h2>
<p>Each <em>Wolbachia</em> mosquito strategy has its strengths: The female approach is broad-reaching and should directly decrease disease transmission. The male strategy effectively lowers the local mosquito population, without releasing female nuisance mosquitoes.</p>
<p>The male release strategies are an important “right-now” fix, but they’ll require an annual, costly release because male mosquitoes – with either MosquitoMate’s <em>Wolbachia</em> or Oxitec’s self-limiting gene – cannot pass on to the next generation their crucial trait. When these males are not being released, fertile wild males will mate with females and the population will rebound.</p>
<p>Eliminate Dengue’s female release strategy is sustainable long-term, but it takes extensive monitoring to ensure the initial establishment of mosquitoes. While MosquitoMate and Oxitec do not disclose their costs, Eliminate Dengue hopes to make their system affordable at a cost of <a href="https://dx.doi.org/10.1038/533450a">approximately US$1 per person</a>.</p>
<p>Some members of the public have <a href="https://dx.doi.org/10.1126/science.aal0350">advocated against these kinds of mosquito release programs</a>, particularly when the mosquitoes have been genetically modified, as with Oxitec’s transgenic insects. While the United States Department of Agriculture received <a href="https://dx.doi.org/10.1038/533450a">2,600 responses to the Oxitec plan, only one response</a> was filed regarding MosquitoMate’s non-GMO strategy.</p>
<p>In the U.S., mosquito control districts are taking a cautious approach. They’re first trying the two nonpermanent male strategies in small areas. The Florida Keys will be <a href="http://keysmosquito.org/2017/03/03/fkmcd-to-test-wolbachia-mosquitoes-in-mid-april/">evaluating mosquitoes on their Stock Island release site for 12 weeks</a>. We should know how effective male <em>Wolbachia</em>-infected mosquitoes are at reducing populations by late summer.</p><img src="https://counter.theconversation.com/content/77541/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michaela Schultz does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Several sites in the US are releasing bacteria-infected mosquitoes as a way to fight mosquito-borne viruses that threaten people. What’s the science – and how well will it work?Michaela Schultz, Graduate Student in Biology, Boston UniversityLicensed as Creative Commons – attribution, no derivatives.