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How Are Mosquitoes Spreading New Health Risks? October 20, 2026 · 7:52 · With Maya, Grace, and Alex
Grace is our columnist for health and medicine, and Alex is our station journalist. Thanks for joining us.
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Maya Welcome to Slow English FM. This is our round table, where we look at one subject from different sides and connect the facts to people’s lives. I’m Maya. Grace is our columnist for health and medicine, and Alex is our station journalist. Thanks for joining us. We’re asking how disease-carrying mosquitoes are spreading, what that means for health, and what communities can do to prepare. Maya Let’s begin with the scale of the health problem. Dengue, chikungunya, and Zika are viruses that can spread through mosquito bites. Grace, what do the latest figures tell us about dengue, and why does mosquito presence matter? Grace The World Health Organization received reports of more than 14.4 million dengue cases in 2024, and 11,201 deaths. More than 90 percent of those reported cases were in the Americas. Dengue is a viral disease spread by mosquitoes in the Aedes group. That group includes species able to carry dengue, chikungunya, and Zika. The number is striking beside the figure for 2000. Santé publique France, the French national public-health agency, reports 505,430 dengue cases worldwide that year. The two figures show a very large rise in reported cases over time. Alex, what has changed in Europe? Alex The European Centre for Disease Prevention and Control, or ECDC, tracks where the Asian tiger mosquito is established. It reported that, by April 2026, this mosquito was established in 384 regional units across 16 European Union and European Economic Area countries. That was 14 more units than in the previous update. The count shows where the mosquito has become established. Maya So the mosquito’s range is expanding. Grace, how can temperature affect what happens after a mosquito bites someone who has a virus? Grace A systematic review looked at 34 laboratory studies of Aedes mosquitoes and dengue, chikungunya, and Zika. Most of the studies found higher rates of infection or transmission in mosquitoes at higher temperatures. But some studies found different results, or no effect. That matters because temperature can affect how well a virus develops inside a mosquito. Temperature is one part of transmission. Maya You mentioned the time the virus needs inside the mosquito. Could you put that in plain language, Grace? Grace Researchers call it the extrinsic incubation period. It means the time between a mosquito picking up a virus and becoming able to pass it on. The review says higher temperatures shortened this period in the studies it examined. In simple terms, the virus may become ready to spread sooner under some conditions. But the results vary by virus, mosquito, and the conditions in each experiment. Alex And it is important to connect that laboratory evidence with what has happened in Europe. The ECDC reported 27 chikungunya outbreaks in Europe in 2025. France also reported its first locally acquired case in the Alsace region. A locally acquired case means the person was infected in that area, rather than bringing the infection from somewhere else. Maya Alex, how does an imported infection become a local health concern? And what happened in France in 2025? Alex An imported infection means a person acquired the disease elsewhere and then arrived in the area. If a local mosquito bites an infected person, the mosquito may be able to carry the virus onward. Institut Pasteur reported at least 1,073 imported chikungunya cases in mainland France in 2025, followed by 788 cases acquired locally. It said health authorities used surveillance and rapid mosquito-control measures to curb transmission. Grace That example shows why health services need to watch both human illness and mosquito populations. Finding imported cases can help authorities spot a possible route for local spread. The figures from Institut Pasteur also show that local transmission occurred after imported cases were recorded. The useful point is that quick detection and mosquito control were part of the response described for France. Maya That brings us to prevention. Alex, there is also a different approach that changes the mosquito population itself. What happened in a trial in Indonesia? Alex A trial in Yogyakarta tested the release of Aedes aegypti mosquitoes carrying Wolbachia, a type of bacterium. The World Mosquito Program, which ran the intervention, reports that a peer-reviewed study found 77 percent lower rates of confirmed dengue and 86 percent fewer dengue hospitalisations in treated areas during the trial. Routine mosquito-control measures continued in both trial groups. Maya Grace, how does that fit with the more familiar approach of watching for cases and controlling mosquitoes? Grace They address the problem in different ways. Surveillance helps identify illness and possible local spread. Mosquito control aims to reduce the insects that can carry a virus. Wolbachia is another tool: in the Yogyakarta trial, mosquitoes carrying the bacterium were released, and dengue illness and hospitalisations were lower in treated areas. The trial kept routine control in place, too. So the reported results support looking at how different measures can work together. Maya Alex, what should listeners take from the European figures, without assuming that every place with tiger mosquitoes faces the same level of danger? Alex The ECDC’s map is useful because it shows the mosquito is established in more regional units than before. The 2025 chikungunya outbreaks show that local transmission has occurred in Europe, including the case in Alsace. The France figures also show that authorities responded with surveillance and mosquito control. Together, those facts make preparation practical: health services need to recognize cases, and local responses can include control of mosquitoes. Maya Grace has explained how temperature can affect virus development inside mosquitoes, while noting that laboratory results vary. Alex has connected the wider mosquito range with real cases and with prevention efforts in France and Indonesia. The central lesson is that mosquito presence, disease transmission, and illness are related, but they are not the same measure. Understanding each one helps communities prepare. Thanks for listening to Slow English FM.
