tag:theconversation.com,2011:/africa/topics/bednets-22287/articlesbednets – The Conversation2022-03-07T14:59:48Ztag:theconversation.com,2011:article/1772582022-03-07T14:59:48Z2022-03-07T14:59:48ZSome malaria parasites are evading detection tests, causing an urgent threat to public health<figure><img src="https://images.theconversation.com/files/447747/original/file-20220222-13-1nqn2c6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Diagnostic is a crucial step in the fight against malaria.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Malaria is an old disease. Yet it continues to have devastating impacts on poor people, especially in Africa. To fight the disease, countries <a href="https://www.who.int/publications/i/item/guidelines-for-malaria">primarily</a> use insecticide-treated bed nets to control the mosquitoes that transmit malaria parasites, or medicines to treat malaria patients. </p>
<p>These measures have been <a href="https://www.who.int/publications/i/item/9789240040496">highly effective</a> over the years. But now they are threatened by mosquitoes resisting the insecticides, and parasites resisting the drug treatments. </p>
<p>Malaria patients are currently treated using <a href="https://www.who.int/publications/i/item/guidelines-for-malaria">artemisinin combination therapy (ACT)</a>. However, patients need timely and accurate diagnosis. This helps to ensure effective treatment and prevents wastage of expensive medicines. </p>
<p>For this purpose, the World Health Organization (WHO) currently recommends either the use of microscopes by trained technicians, or rapid diagnostic tests.</p>
<p>Microscopy has been practised for more than a century. It’s generally very reliable for detecting and identifying specific malaria parasites. But it <a href="https://link.springer.com/article/10.1007/BF03256295">requires</a> highly skilled experts, reliable equipment, and stable electricity as well as high-quality reagents. Providing these can be a challenge, especially in rural areas. </p>
<p>Thus in 2010, <a href="http://whqlibdoc.who.int/publications/2010/9789241547925_eng.pdf">WHO recommended</a> that malaria-endemic countries should introduce rapid diagnostic tests in all healthcare facilities as the main diagnostic platform. This strategy has <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0018419">significantly</a> enhanced malaria management by guiding appropriate medication.</p>
<p>A more recent concern, however, is that parasites are becoming resistant to the methods used for malaria diagnosis.</p>
<p>Current rapid diagnostic tests detect a specific parasite protein (HRP2) in the patient’s blood. But <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0008091">evidence</a> shows that malaria parasites in some locations have changed their genetic make-up so that they no longer produce this protein. This results in diagnostic resistance. Rapid diagnostic tests can’t detect these changed parasites even in patients who are severely ill with malaria. </p>
<p>This presents a major public health threat to malaria-endemic countries as well as the ongoing global elimination efforts. There are steps that can be taken to avoid a worst case scenario. These are: improving surveillance, responding quickly to diagnostic resistance, finding alternative diagnostic methods, and global and national cooperation.</p>
<h2>Status of diagnostic resistance</h2>
<p>Malaria parasites lacking the HRP2 protein have been <a href="https://www.who.int/publications/m/item/WHO-UCN-GMP-2021.09">detected globally</a>. In countries in the Horn of Africa, notably <a href="https://malariajournal.biomedcentral.com/articles/10.1186/s12936-017-1752-9">Eritrea</a>, the rapid diagnostic tests based on that protein missed 60%-80% of infections in 2016. Switching to a different test for two years resulted in a remarkable <a href="https://www.nature.com/articles/s41598-021-00714-8.pdf">reduction to less than 42%</a>. In Ethiopia, undetectable parasites now make up about <a href="https://www.nature.com/articles/s41564-021-00962-4.pdf">10% of all malaria infections</a>. </p>
<p>The new alternative tests are expensive, not readily available and are often less sensitive. </p>
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<a href="https://theconversation.com/the-warning-lights-are-on-for-malaria-medicines-in-africa-172700">The warning lights are on for malaria medicines in Africa</a>
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<p>Other African countries have also reported the presence of <a href="https://academic.oup.com/jid/article/220/9/1444/5524476">diagnostic resistance</a>. The levels are still below the WHO <a href="https://www.who.int/docs/default-source/documents/publications/gmp/false-negative-rdt-results.pdf?sfvrsn=ec917b72_2">thresholds</a> required for changing the rapid diagnostic tests. This is good news for now. But changes can occur rapidly because undetectable parasites generally remain untreated and can continue spreading in communities. In Tanzania undetectable parasites have been <a href="https://malariajournal.biomedcentral.com/articles/10.1186/s12936-020-03459-3">reported</a> sporadically.</p>
<h2>Preventing a worse problem</h2>
<p>There are four ways to deal with diagnostic resistance before it gets worse. </p>
<p>First, intensified <a href="https://mesamalaria.org/mesa-track/molecular-surveillance-malaria-parasite-populations-and-antimalarial-drug-resistance">surveillance</a> is highly recommended. All countries should use new molecular methods recommended by WHO to map the existence of parasites that don’t produce HRP2 protein. Surveillance will enable health authorities to act on diagnostic resistance before it reaches unmanageable levels.</p>
<p>The WHO is closely monitoring the status of diagnostic resistance globally. It has put forward <a href="https://apps.who.int/iris/bitstream/handle/10665/331197/9789240002050-eng.pdf">guidelines</a> on how and when countries need to investigate the incidents. Experts and reference laboratories with technical capacity for analysing the parasites have also been identified. </p>
<p>Second, the national malaria control programmes in all countries should monitor the quality and performance of rapid diagnostic tests. If there are any suspicious reports or complaints, they should act immediately. Inability of tests to detect malaria infections results in untreated patients who can further spread the parasites. </p>
<p>Third, where parasites with diagnostic resistance are known to be circulating, governments should provide management guidelines. Alternative diagnostic methods should be made available. These could be microscopy or another kind of rapid diagnostic test. Service providers should be made aware of the problem and what they can do about it. This will ensure suspected malaria patients with negative results are investigated and managed properly. The patients should be re-tested and reports should be submitted to local health authorities to ensure adequate monitoring of the situation.</p>
<p>Finally, malaria programmes, research institutions and experts must work together to address this issue. It’s especially urgent now when most countries are transitioning from the era of control to elimination. Scientists must look for new ways of detecting malaria parasites so that there are other options when the current tests are no longer useful. New methods and efforts to eliminate malaria by targeting mosquitoes and effectively treating patients to prevent onward transmission must be strengthened and scaled-up by all countries. The WHO and global community should support malaria-affected countries to strengthen their capacity to tackle this challenge.</p>
<p><em>Catherine Bakari, a PhD student based at the National Institute for Medical Research (NIMR) in Tanzania, contributed to this article.</em></p><img src="https://counter.theconversation.com/content/177258/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Deus Ishengoma receives funding from the Bill & Melinda Gates Foundation, the World Health Organization, US President’s Malaria Initiative, and the US National Institute of Health.</span></em></p><p class="fine-print"><em><span>Fredros Okumu receives funding from the Bill & Melinda Gates Foundation and the Wellcome Trust, UK among others,</span></em></p>Evidence shows that malaria parasites in some locations have changed their genetic make-up so that they can evade rapid diagnostic tests.Deus Ishengoma, Principal Research Scientist, National Institute for Medical Research (NIMR)Fredros Okumu, Director of Science, Ifakara Health InstituteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1696392021-10-11T15:06:13Z2021-10-11T15:06:13ZMalaria vaccine is a major leap forward: but innovation mustn’t stop here<figure><img src="https://images.theconversation.com/files/425668/original/file-20211011-18-73vdg2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A health worker prepares a malaria vaccination in Yala, Kenya</span> <span class="attribution"><span class="source">Brian Ongoro / AFP via Getty Images</span></span></figcaption></figure><p>The World Health Organisation (WHO) took an historic step in the fight against malaria when it recently recommended the use of a <a href="https://www.who.int/news/item/06-10-2021-who-recommends-groundbreaking-malaria-vaccine-for-children-at-risk">malaria vaccine</a> for young children. The announcement marked a major achievement – the development of the first ever successful malaria vaccine against <em>falciparum</em> malaria, the deadliest form of malaria and the one that is most common in sub-Saharan Africa.</p>
<p>The wide uptake of the vaccine could prevent thousands of deaths in the region. According to the <a href="https://www.who.int/publications/i/item/9789240015791">2020 World Malaria Report</a>, over 250,000 children under the age of five years died of malaria in Africa in 2019. That is a very sombre statistic for a treatable and preventable disease.</p>
<p>The development of the vaccine (called RTS,S) has taken <a href="https://www.malariavaccine.org/sites/mvi/files/content/page/files/PATH_MVI_RTSS_Fact%20sheet_042019.pdf">over 30 years</a>. It is the culmination of work by researchers from the Walter Reed Army Institute of Research, in partnership with the pharmaceutical company GlaxoSmithKline and the global health organisation PATH.</p>
<p>Producing an effective malaria vaccine has been challenging as the malaria parasite is able to hide from the human immune system. In addition, different forms of the malaria parasite infect the liver and red blood cells. </p>
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Read more:
<a href="https://theconversation.com/why-does-malaria-recur-how-pieces-of-the-puzzle-are-slowly-being-filled-in-108833">Why does malaria recur? How pieces of the puzzle are slowly being filled in</a>
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<p>Vaccine trials were started in 2019 in three <a href="https://www.who.int/docs/default-source/immunization/mvip/mvip-milestones-to-programme-development-final.pdf?sfvrsn=14768db0_4">African countries</a> – Ghana, Kenya and Malawi. The study showed that the RTS,S vaccine was safe in young children, that it reduced hospitalisation and death in vaccinated children by over <a href="https://www.lshtm.ac.uk/newsevents/news/2021/severe-malaria-among-young-african-children-dramatically-reduced-through">70%</a>, and that a successful malaria vaccination programme was possible in rural African settings. </p>
<p>The pilot study also showed that the vaccine was able to reach children who were not being protected by other methods like bed nets in the <a href="https://www.who.int/director-general/speeches/detail/who-director-general-s-opening-remarks-on-who-recommendation-for-wider-use-of-the-rts-s-malaria-vaccine">study sites</a>. This provided additional support to the calls for the widespread use of the vaccine in malaria-affected areas.</p>
<p><a href="https://www.who.int/publications/i/item/9789240015791">Since 2015</a> malaria case numbers have been either flat or on the rise. This follows 15 years during which the numbers had been on the decline.</p>
<p>The addition of the RTS,S vaccine to the malaria control and elimination toolkit could get global efforts back on track. But it cannot be viewed as the silver bullet required to achieve malaria elimination. </p>
<h2>Not a complete solution</h2>
<p>The vaccine has several <a href="https://www.tandfonline.com/doi/pdf/10.1080/21645515.2019.1669415?needAccess=true">shortcomings</a>. </p>
<p>Firstly, in its current form it only works very effectively in very young children, aged between five and 17 months. These children must be given three vaccine doses, at least one month apart. A fourth booster dose is recommended at 18 months for the vaccine to work optimally.</p>
<p>This is makes running an effective vaccination programme very challenging. One possible solution is using community-based vaccination programmes to increase access and improve compliance.</p>
<p>In addition, although the vaccine prevents severe disease, it doesn’t necessarily prevent infection. This is similar to the <a href="https://www.who.int/news-room/feature-stories/detail/vaccine-efficacy-effectiveness-and-protection">COVID-19 vaccines</a>. </p>
<p>Thirdly, it’s only effective against one (<em>Plasmodium falciparum</em>) of the five human malaria parasites. </p>
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Read more:
<a href="https://theconversation.com/breakthrough-malaria-vaccine-offers-to-reinvigorate-the-fight-against-the-disease-169500">Breakthrough malaria vaccine offers to reinvigorate the fight against the disease</a>
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<p>There are other concerns too. One is increased <a href="https://www.africaportal.org/features/myths-and-models-whats-driving-vaccine-hesitancy-in-africa-and-how-can-we-overcome-it/">vaccine hesitancy</a> across Africa.</p>
<p>There are also likely to be challenges in meeting the demand for vaccines, given the current focus on producing COVID-19 vaccines. </p>
<p>In light of these challenges, the RTS,S vaccine cannot replace existing effective interventions. These include indoor residual spraying and the use of insecticide treated bed nets. Instead, the vaccine must be used <a href="https://www.who.int/director-general/speeches/detail/who-director-general-s-opening-remarks-on-who-recommendation-for-wider-use-of-the-rts-s-malaria-vaccine">alongside these</a> to break the malaria transmission cycle.</p>
<p>As the RTS,S vaccine is only effective in young children, it will only be used where they are at higher risk of infection than older children. Such conditions are generally found in <a href="https://www.who.int/news/item/06-10-2021-who-recommends-groundbreaking-malaria-vaccine-for-children-at-risk">moderate to high transmission areas</a>. In these areas, frequent malaria infections result in older children developing partial immunity. </p>
<p>This immunity prevents children from showing the signs and symptoms of malaria. They become asymptomatic carriers of malaria. Many malaria-endemic African countries, including Botswana, Eswatini, Namibia and South Africa, have very low transmission intensities, so the population does not develop immunity against malaria. </p>
<p>Including the RTS,S vaccine in a childhood immunisation programme in these low transmission countries would not be cost-effective.</p>
<p>Despite the challenges associated with the RTS,S vaccine, its addition to the suite of malaria control interventions is a leap forward in the global fight against malaria. But vaccine innovation must not stop here. Efforts must be put into developing a vaccine that is effective in older children and adults, which requires only one dose and is effective against all human malarias.</p><img src="https://counter.theconversation.com/content/169639/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jaishree Raman receives funding from the National Research Foundation of South Africa, the National Health Laboratory Services Research Trust and the Bill and Melinda Gates Foundation. She is affiliated with Centre for Emerging Zoonotic Diseases, National Institute for Communicable Diseases, the Wits Research for Malaria, University of Witwatersrand and the UP Institute for Sustainable Malaria Control, University of Pretoria.</span></em></p><p class="fine-print"><em><span>Shüné Oliver receives funding from the National Research Foundation of South Africa and the National Health Laboratory Services Services Research Trust. She is affiliated with Centre for Emerging Zoonotic Diseases, National Institute for Communicable Diseases and the Wits Research for Malaria, University of Witwatersrand</span></em></p>The successful development of an effective vaccine against the deadliest form of malaria that is most common in sub-Saharan Africa is indeed a major achievement.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/765332017-04-24T15:59:47Z2017-04-24T15:59:47ZMosquito discovery sheds light on how malaria is spread in South Africa<figure><img src="https://images.theconversation.com/files/166494/original/file-20170424-12650-e50q0e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A second Malaria causing mosquito has been discovered in South Africa .</span> <span class="attribution"><span class="source">Flickr</span></span></figcaption></figure><p>Across the world there are limited tools available for controlling mosquitoes. The two <a href="https://malariajournal.biomedcentral.com/articles/10.1186/1475-2875-12-62">most successful</a> and widely used initiatives are indoor house spraying and the use of insecticide treated bed nets. These target mosquitoes that feed on humans inside their homes and then rest indoors. Hundreds of millions of bed nets have been distributed across Africa in the <a href="http://apps.who.int/iris/bitstream/10665/200018/1/9789241565158_eng.pdf">last 15 years</a>. </p>
<p>But there are no methods that control mosquitoes that operate outdoors. This is a major challenge across the continent. It poses a particular problem for South Africa which has set itself the goal of <a href="https://theconversation.com/parts-of-southern-africa-are-within-tantalising-reach-of-eliminating-malaria-49848">eliminating malaria by 2018</a>.</p>
<p>The reason is the variable behaviour of the main malaria carrying mosquito in the country, <em>Anopheles arabiensis</em>. Although it prefers to feed on people inside their houses – and rest there while its eggs develop – it’s not averse to doing so outside. This makes it less amenable to house spraying which means that it’s never completely eradicated from an area.</p>
<p><a href="https://www.nature.com/articles/srep43779">Our research</a> has uncovered that another mosquito vector, <em>Anopheles vaneedeni</em>, also carries the parasite and is also amenable to biting and breeding outside. <em>Anopheles vaneedeni</em> has been known about since 1977, it has never – before now – been identified as a malaria carrying vector in nature. </p>
<p>Our discovery is a step in the right direction. It gives weight to the view that until effective methods are developed for controlling outdoor mosquitoes, eliminating local malaria transmission in southern Africa will be extremely difficult. The fact that we now know about <em>Anopheles vaneedeni</em> means that we can target our research towards knowing more about this vector’s behaviour. This, in turn, can open the door to finding solutions.</p>
<h2>South Africa’s history with malaria</h2>
<p>Historically there were cases of malaria throughout the north-eastern areas of the country which have subtropical climates: Limpopo, Gauteng, Mpumalanga and KwaZulu-Natal. There have been epidemics around Pretoria and as far south as Port St Johns on the south east coast. In 1932, for example, there were over 22,000 deaths from malaria in northern Kwazulu-Natal. </p>
<p>South Africa adopted malaria intervention strategies as early as the 1950s. As a result, the burden was reduced and areas affected by the disease shrank. Now only the far north-eastern part of Limpopo Province, eastern Mpumalanga and far northern Kwazulu-Natal, bordering Mozambique, continue to be affected. </p>
<p>South Africa has a long history of intense malaria control activities. Entomologists in the country have been studying malaria mosquitoes for close to 100 years. </p>
<p>South Africa was a pioneer in one of the early methods adopted by the World Health Organisation (WHO) to fight malaria. Extensive surveys conducted in parts of the country showed how effective it was to spray insecticides indoors to protect people from mosquito bites. This method was adopted by the WHO in the 1950s for their <a href="http://www.who.int/malaria/about_us/en/">global malaria eradication programme</a>. </p>
<p>As part of our research we assist the provincial malaria control programmes by collecting mosquitoes and doing the necessary laboratory analysis to identify the species and detect malaria parasites in these mosquitoes. </p>
<h2>What we found, and the significance</h2>
<p>We carried out an extensive collection of mosquitoes in outdoor resting places such as clay pots and modified plastic buckets. Using these methods, we found that <em>Anopheles vaneedeni</em> was indeed carrying the parasite. </p>
<p>This species was shown to be capable of transmitting malaria parasites in laboratory experiments in 1977, but has not, until now, been implicated in transmission in the field. It will happily feed on humans outdoors, and definitely liked our outdoor clay pots as resting sites.</p>
<p>We also found specimens of both <em>Anopheles arabiensis</em> in the clay pots. Until now it was thought that only this species was responsible for ongoing malaria transmission in South Africa. We now know that this situation is more complex because other Anopheles species is also responsible for the ongoing transmission.</p>
<h2>The trouble with outdoor vectors</h2>
<p>It’s now clear that the drivers of malaria in South Africa are more complicated than previously believed. Methods that target the immature stages of the mosquito’s life cycle – such as when the larvae breed in rain pools, ponds, swamps, streams, rice paddies – are generally only applicable in very specific situations. It would be impossible to treat every rain puddle on the continent. </p>
<p>Another intervention being explored is the use of sterile male mosquitoes – female mosquitoes mate only once in their lifetime and if the male is sterile, she will not produce viable eggs. </p>
<p>We are also testing novel compounds that might disrupt the parasite development inside the mosquito or kill mosquitoes that feed on cattle. </p>
<p>A lot of research, internationally, is going on into novel traps and control methods and we are collaborating with groups in the UK, US and Tanzania who want to test these methods. </p>
<p>The first step towards a successful malaria control or elimination programme, is “knowing the vector”. That means understanding the behaviour of the mosquitoes – their feeding and resting patterns, the mating behaviour of the males and females, the preferred aquatic habitat of the immature stages, their geographic distribution, and what their response is to insecticides. The Anopheles vaneedeni can now also be studied in this light.</p><img src="https://counter.theconversation.com/content/76533/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Maureen Coetzee receives funding from the National Research Foundation, the Medical Research Council, UK-MRC/DFID, Wellcome Trust and US-NIH. </span></em></p><p class="fine-print"><em><span>Basil Brooke receives funding from the National Research Foundation, the Medical Research Council of South Africa and the Centres for Disease Control & Prevention (GDD). </span></em></p><p class="fine-print"><em><span>Lizette Koekemoer receives funding from NTeMBI. Department of Science and Technology and the International Atomic Energy Agency. </span></em></p>Malaria in South Africa is close to being eliminated but to complicate matters scientists have identified a second mosquito transmitting the disease.Maureen Coetzee, Director of Wits Research Institute for Malaria in the Faculty of Health Sciences, University of the WitwatersrandBasil Brooke, Associate Professor at the Wits Research Institute for Malaria in the Faculty of Health Sciences, University of the WitwatersrandLizette Koekemoer, Associate Professor at the Wits Research Institute for Malaria in the Faculty of Health Sciences, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/763582017-04-24T13:43:12Z2017-04-24T13:43:12ZKenyan study shows why reusing old mosquito nets should be encouraged<figure><img src="https://images.theconversation.com/files/166305/original/file-20170421-22929-10zd2yc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Millions of mosquito bed nets have been distributed in Africa.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p><em>Treated mosquito nets are <a href="http://www.gla.ac.uk/news/archiveofnews/2016/july/headline_474682_en.html">vital</a> in the fight against malaria. But the average lifespan of a net is about <a href="https://www.againstmalaria.com/faq_bednets.aspx">four years</a>. The Conversation Africa’s Health and Medicine Editor Joy Wanja Muraya asked Dr Lydiah Kibe to explain how old and torn bed nets are being reused in coastal Kenya.</em></p>
<p><strong>Why are treated bed nets a critical protective barrier against mosquitoes?</strong></p>
<p>Mosquitoes are a nuisance and cause irritation. On the public health front, they transmit diseases such as malaria, <a href="http://www.who.int/mediacentre/factsheets/fs207/en/">Rift Valley Fever</a>, <a href="http://www.who.int/mediacentre/factsheets/fs117/en/">Dengue fever</a>, <a href="http://www.who.int/mediacentre/factsheets/zika/en/">Zika virus</a> and <a href="http://www.who.int/mediacentre/factsheets/fs327/en/">Chikungunya</a>, yellow fever, filariasis among others.</p>
<p>One of the key ways mosquitoes are controlled is through the use of insecticide treated nets which are hung over beds, especially at night.</p>
<p>Insecticide treated nets <a href="https://parasitesandvectors.biomedcentral.com/articles/10.1186/1756-3305-4-113">reduce</a> illnesses and deaths from malaria. It can <a href="http://onlinelibrary.wiley.com/wol1/doi/10.1002/14651858.CD000363.pub2/full">reduce deaths</a> in children by a fifth and episodes of malaria by half.</p>
<p>Since 2002 about 30 million nets have been<a href="http://www.ifrc.org/ar/noticias/noticias/africa/kenya/34-million-mosquito-nets-distributed-in-kenya/"> distributed</a> in Kenya to high risk groups especially pregnant women and children under five years.</p>
<p>In 2006, about 3.4 million <a href="http://www.who.int/mediacentre/news/releases/2007/pr43/en/">Long Lasting Insecticides Nets</a> were given at no cost to children under five in malaria endemic areas in Kenya. Six years later, 11.5 million treated nets were <a href="https://www.unicef.org/media/media_62293.html">distributed</a> in the 87 <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3310610/">malaria prone</a> regions in the western, coast and parts of eastern Kenya. Furthermore, a mass distribution campaign is underway in Kenya to provide <a href="http://www.capitalfm.co.ke/news/2017/03/mass-distribution-15mn-mosquito-nets-kicks-off-23-counties/">15 million treated</a> nets in 23 malaria prone counties. </p>
<p>The aim is to achieve <a href="http://www.who.int/malaria/publications/atoz/who-clarification-estimating-population-access-itn-mar2014.pdf">universal coverage</a>, targeting one treated bed net per two household members.</p>
<p>Other interventions used to control mosquitoes include; </p>
<ul>
<li><p>aerosols- a spray that contains a natural active ingredient that kills mosquitoes</p></li>
<li><p>repellents- applied to skin, clothing, or other surfaces to discourage mosquitoes from landing or climbing on that surface</p></li>
<li><p>screening windows and eaves- netting material mostly on windows that prevents entry of mosquitoes</p></li>
<li><p>larviciding- an insecticide that specifically targets the larval life stage of a mosquito</p></li>
</ul>
<p><strong>What motivated your study into how old nets are being used?</strong></p>
<p>Our <a href="https://malariaworld.org/mwj/2015/research-formative-study-disposal-and-re-use-old-mosquito-nets-communities-malindi-kenya">study</a> was done in 888 households in Malindi, coastal Kenya. It was motivated by a lack of guidelines on disposing old, expired and torn mosquito nets especially after a mass distribution. We investigated the reuse of bed nets, particularly those that were old, torn and expired bed nets. The nets are made of polyethylene or polyester materials which are strong and long lasting. </p>
<p>There are no official guidelines to follow, but we found that residents had devised imaginative, creative and innovative ways of recycling them. </p>
<p>The most popular reuses we found were:</p>
<ul>
<li><p>a quarter of the respondents had used them to reinforce fences and shelters</p></li>
<li><p>as net ropes for tying animals</p></li>
<li><p>building and furniture materials (23%)</p></li>
<li><p>protecting seedlings (17%)</p></li>
<li><p>as chicken coops (13%) </p></li>
<li><p>as window screens (11%)</p></li>
<li><p>covering wells and water containers (4%)</p></li>
<li><p>to scrub utensils</p></li>
<li><p>as a sponge for personal hygiene during bathing</p></li>
</ul>
<p>Children also put them to use. We found that they had been fashioned into goal posts, strings and jumping ropes as well as swings.</p>
<p>We also found that women liked to use the material to make a traditional attire known as <a href="https://www.standardmedia.co.ke/business/article/1144001979/malindi-women-celebrate-the-traditional-hando"><em>hando</em></a> – a short skirt made of a long material, preferably cotton, folded into gathers. These are usually made from old clothes or material made from sisal.</p>
<p><strong>What reasons were given for the disposal of the bed nets?</strong></p>
<p>Nets eventually become ineffective. This happens when they are old, worn out and insecticidal activity is reduced. Residents dispose them once they’ve been repaired them many times or the holes have become too big and numerous.</p>
<p>Damage to nets is often caused by tin lamps, friction from a mat or edge of the bed, sparks from a fire and children playing with them. They were also often washed frequently.</p>
<p>This is what some respondents had to say about why they disposed of the nets:</p>
<blockquote>
<p>My net had big holes like the size of my fist and mosquitoes were entering through these holes. I had to buy another net to replace it.</p>
<p>Our houses are like you can see them (referring to mud thatched houses). We sleep with our chicken and goats inside the house. This makes the nets get dirty very fast as the goats sometimes urinate on the nets. You have to wash it regularly and this makes it get torn very fast.</p>
<p>Sometimes you repair the holes until the net cannot be repaired anymore. You repair it today, after a week you find another bigger one. If it’s old you throw it away in the trash and get a new one or stay without one.</p>
</blockquote>
<p><strong>What next?</strong></p>
<p>It’s time that alternative uses of old and worn out nets wasn’t interpreted as misuse but seen as an innovative way of using them.</p>
<p>However, health promotion officers should provide guidance on alternative uses. For example, people could be encouraged to use them in a way that compliments malaria control efforts such as using them as window screens and covering water wells.</p>
<p>In addition, efforts should be made to involve communities in viable and realistic ways of reusing old nets. This could be done without compromising the overall goals of malaria control initiatives. For example, they could serve as alternative sources of income by encouraging collection, sorting and making ropes which could then be sold.</p><img src="https://counter.theconversation.com/content/76358/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lydiah Kibe receives funding from KEMRI Internal Research Grants; Biovision Foundation - Switzerland; University of Camerino - PhD Study Fellowship.
</span></em></p>Mosquitoes are controlled by insecticide treated nets to curb the spread of Malaria. The nets which are hung over beds can be reused after serving its purpose.Lydiah Kibe, Research Officer, Kenya Medical Research InstituteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/621262016-07-11T21:05:42Z2016-07-11T21:05:42ZMalaria: should we abandon insecticide-treated bednets?<figure><img src="https://images.theconversation.com/files/129884/original/image-20160708-24079-myanab.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/dl2_lim.mhtml?src=aameXJdcHLkf3zd2yjPLdA-2-3&clicksrc=download_btn_inline&id=286728137&size=medium_jpg&submit_jpg=">punghi/Shutterstock</a></span></figcaption></figure><p>In Africa, some malaria-carrying mosquitoes have found ways to survive exposure to insecticides. This means that bednets treated with these chemicals may become less effective at preventing malaria. A new study we’ve published in <a href="http://www.pnas.org/content/early/2016/07/05/1603431113.abstract">PNAS</a> shows that although these resistant mosquitoes don’t die immediately on contact with insecticide-treated bednets, their risk of death in the days and weeks following contact is greatly increased. As a result, the opportunity for these mosquitoes to transmit malaria to a human drops by two-thirds.</p>
<p>There were over 200m cases of malaria in <a href="http://www.who.int/malaria/media/world-malaria-report-2015/en/">2015</a>, causing more than 400,000 deaths, mostly in Africa. While these numbers are still shockingly high, <a href="http://www.nature.com/nature/journal/v526/n7572/abs/nature15535.html">since 2000</a>, the rates of malaria have been decreasing dramatically, largely due to the widespread use of insecticide-treated bednets.</p>
<p>Such bednets help control malaria in two different ways: by providing a physical barrier between the human and the disease infected mosquito; or by turning the person sleeping under the bednet into a deadly mosquito trap, where the mosquito is lured towards the scent of the sleeper. The mosquito then flies into a wall of insecticide that not only stops it from biting but kills it too. So impregnating bednets with insecticide has been very useful for controlling malaria mosquito populations.</p>
<p>The problem with the widespread use of insecticide-treated bednets is that many mosquitoes have now become highly resistant to these chemicals. Insecticides are designed to kill mosquitoes immediately on contact, so when more than 10% of them are still alive in the day following exposure we know they are getting resistant to insecticides. </p>
<p>To worsen the problem, there is only one type of insecticide that can be safely used to treat bednets. So when mosquitoes become fully resistant, we could enter an era where our primary weapon against malaria can no longer be used and the public health gains achieved so far reversed.</p>
<h2>Thinking beyond 24 hours</h2>
<p>While the spread of insecticide resistance is of great concern, our results indicate that by classifying mosquitoes as resistant only on the basis of mosquito survival in the 24 hours following exposure, we are overseeing important long-term costs arising from exposure to insecticides. By rearing thousands of mosquitoes in the laboratory and exposing them to nets impregnated with insecticides we were able to closely monitor the longer-term fate of resistant mosquitoes that encounter an insecticide-treated bednet. We found that while they survive the first day, there were consistent reductions in their daily survival for the rest of their lives. Over the life time of the mosquito, these small but consistent reductions combine to reduce their lifespan by half. </p>
<p>The malaria parasites needs at least nine days to mature inside the mosquito before they can be passed onto a human, so these longer-term survival reductions could have a big impact on malaria transmission. </p>
<p>In total, we estimated that contact with a treated bednet can reduce the transmission potential of even highly resistant mosquitoes by two-thirds. This may explain why bednets appear to be effectively controlling malaria in areas of Africa where mosquito populations are highly resistant. So for now, it would be premature to abandon this strategy.</p>
<p>Unfortunately, we also found evidence that these longer-term impacts on mosquito survival may be temporary and could disappear as mosquitoes develop more intense levels of resistance. This is why there remains a huge urgency to find alternative methods to control malaria mosquitoes. </p>
<p>By making new insecticidal products - or finding alternative or other complementary solutions - we may be able to start killing these resistant mosquitoes again. As we wait for these developments, we should continue to use mosquito insecticide-treated bednets. Despite the rapid spread of insecticide resistance, they are still the most effective method to prevent malaria transmission.</p><img src="https://counter.theconversation.com/content/62126/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mafalda Viana receives funding from MRC. </span></em></p><p class="fine-print"><em><span>Angela Hughes 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>Bednet insecticides should kill mosquitoes on contact, but some have become highly resistant to the chemicals.Mafalda Viana, Research fellow, University of GlasgowAngela Hughes, Laboratory Manager/PhD studentLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/498732015-11-04T04:05:01Z2015-11-04T04:05:01ZSeven things worth knowing about mosquitoes<figure><img src="https://images.theconversation.com/files/100535/original/image-20151102-16527-1dthulh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Anopheles Gambiae, one of three mosquitoes found in Africa that transmit malaria.</span> <span class="attribution"><span class="source">shutterstock</span></span></figcaption></figure><p><em><em>This article is part of a series The Conversation Africa is running as part of the South African Development Community malaria week. You can read the rest of the series <a href="https://theconversation.com/africa/topics/sadc-malaria-week">here</a>.</em></em></p>
<p><strong>1. Not all mosquitoes bite.</strong></p>
<p>The female mosquitoes are the dangerous ones. They bite and draw blood. Male mosquitoes feed on flower nectar. Males have very hairy and fuzzy antennae (like a powder puff) whereas females have less hairy antennae. </p>
<p><strong>2. There are three types of malaria carrying mosquitoes.</strong></p>
<p>The top three malaria transmitters in Africa are Anopheles gambiae, Anopheles funestus and Anopheles arabiensis. The first two live in areas of Africa where there is higher rainfall while the third, Anopheles arabiensis, is a more savanna-based, arid zone species. </p>
<p>Gambiae and funestus prefer to feed indoors and are strongly attracted to humans, but arabiensis feeds as easily outdoors as indoors and also as easily on cattle and other animals as humans. This means it is easier to target gambiae and funestus using indoor methods such as spraying walls with insecticides and using insecticide-impregnated bed nets. The outdoor-feeding arabiensis is far more difficult to control. </p>
<p>In most areas all three species have a peak of biting in the early hours of the morning when people are in their deepest sleep and less likely to disturb mosquitoes during the feeding process. There are also other important species of malaria-transmitting mosquitoes but they are more localised in distribution.</p>
<p><strong>3. Mosquitoes have started to change their feeding patterns.</strong></p>
<p>Because of the strong focus on indoor strategies to fight malaria transmitting mosquitoes using bed nets and indoor spraying, genetic selection is resulting in some populations of these mosquitoes biting outdoors and earlier at night when people are not protected by bed nets. It means these mosquitoes are more difficult to reach with insecticides, just as is the case with Anopheles arabiensis.</p>
<p><strong>4. Most mosquito bites are harmless. It’s only the ones that carry certain types of parasites that lead to malaria, and potentially death.</strong></p>
<p>In Africa, there are four known species of microscopically small parasites that can cause the disease we call malaria. All four belong to the group <em>Plasmodium</em>. The most common of these parasites in Africa is <em>Plasmodium falciparum</em>, which is the most deadly of the four species. </p>
<p>Birds and some other groups of animals carry their own species of <em>Plasmodium</em>, which is also transmitted by mosquitoes, but they do not cause malaria in humans. Mosquitoes also carry many other disease-causing organisms such as yellow fever virus, West Nile virus, Rift Valley fever, and the worms that cause the dreaded disfiguring elephantiasis (filariasis).</p>
<p><strong>5. Mosquitoes select where they feed on the body. They have very acute sensory mechanisms (like heat-seeking missiles) that lead them to select particular parts of the body (such as ankles) to feed from.</strong></p>
<p>All three of the main malaria carrying mosquitoes have similar biting preferences. If you are sitting or standing outside in the evening the overwhelming majority will try to feed on your ankles and feet - so make sure you cover these areas with repellent or wear socks and shoes.</p>
<p>The antennae of mosquitoes are highly specialised sensory organs that can detect very small amounts of chemical cues that lead them to food and mates. Various chemicals, of which carbon dioxide is one, help female mosquitoes track down their hosts. Pheromones, which are hormones secreted as odours into the environment, enable males and females to meet and mate. They are also detected by the antennae.</p>
<p><strong>6. Malaria mosquitoes do not like wind.</strong></p>
<p>Using a fan over you when going to bed will lessen your chances of being bitten. These mosquitoes don’t like flying when there is even a slight breeze.</p>
<p><strong>7. 97 countries and territories still face ongoing malaria transmission.</strong></p>
<p>According to the World Health Organisation, an estimated 3.2 billion people, or just under half the world’s population, are at risk of getting malaria. The bulk of the malaria burden is shouldered by Africa where 89% of cases and 91% of deaths occur.</p><img src="https://counter.theconversation.com/content/49873/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Professor Leo Braack received funding from Bill & Melinda Gates Foundation and also University of Pretoria to conduct malaria research</span></em></p>The irritating buzz that rings in your ear in the dead of the night comes from an insect barely traceable with your naked eye. Here are a few facts worth knowing about the mosquito.Leo Braack, Research Chair, Integrated Vector Management in the Vector Control Cluster, Centre for Sustainable Malaria Control , University of PretoriaLicensed as Creative Commons – attribution, no derivatives.