Mosquito-borne diseases: ‘As world warms, parasites, diseases and viruses become more transmissible’

Mosquito-borne diseases: ‘As world warms, parasites, diseases and viruses become more transmissible’

This week, the EU’s health agency warned that Europe has seen a record number of outbreaks of mosquito-born illnesses this year. The European Center for Disease Prevention and Control said that the rise is driven by climate change, which leads to longer and more intense transmission seasons. Tiger mosquitoes, which spread viruses like chicken gona and deni, are now established in over three times as many European regions as they were 10 years ago. For more, we can bring in Thomas Churcher, a professor of infectious disease dynamics at the Imperial College London. Good morning. Thank you so much for taking the time to speak with us today. Good morning. Can you start by explaining a bit more about how these diseases spread and why climate change exacerbates the problem? So these diseases are spread from person to person by mosquitoes and mosquitoes are cold-blooded and so um their activity and the development of the virus and other parasites inside the mosquito is entirely dependent on the temperature that the mosquito is at. So as the the world warms these parasites and these diseases, these viruses get more transmissible and we see more chains of transmission. Okay. So, it’s not just that the mosquitoes are sort of spreading because of climate change to areas further north, but the mosquitoes themselves are are more capable of spreading the disease. Exactly. There’s these two things going on which are probably related as in over the last couple of years, we’ve seen these tiger mosquitoes expanding throughout Europe and these tiger mosquitoes are very good vectors for a a wide number of different diseases. And also as it gets warmer, these diseases are spread from person to person via these mosquitoes much easier. Can you talk a bit more about some of the viruses that we’re seeing getting spread and and what their symptoms are? So there’s a whole wide range of uh viral uh diseases that are spread by these mosquitoes ranging from something like deni fever to chicken ga and zika. And these these diseases are often endemic and and common in in hotter parts of the world and they can cause uh a wide range of uh diseases uh and and lots of the symptoms from them are not particularly obvious. So they’re kind of fever, headache, other things that that you might be getting from other viruses. So it’s not entirely obvious when you have a new outbreak of these diseases. And what about the bite itself? I mean, does a does a mosquito bite from an infected mosquito look or feel any different from just a regular mosquito bite? No, it doesn’t. You don’t you don’t really know. Obviously, you know, the nuisance factor of of mosquitoes is is a real problem and and and and you know, they’re they’re a pest, but uh you don’t really understand whether they’re transmitting the disease until you’ve actually had quite a lot of transmission going on and actually clusters of cases are together that you actually identify that being an issue. At this point, how should people in Europe be protecting themselves? I mean, would it would starting to sleep under a mosquito net of, for example, be be considered an overreaction? Well, so these mosquitoes, the celing, the tiger mosquito that we’re talking about, doesn’t actually just bite at night. It bites often during the day and and the time when you’re sitting outside in the evening. Um, so, you know, any mosquito prevention, you getting bitten yourself will will help. But unfortunately these this is an issue that you can’t just solve by yourself. It’s something that we all need to do together. And so for example countries like Singapore uh they are very strong in preventing people from having for example upturn water things in their garden that is where the mosquito breeds and therefore acts as a kind of a center for new for new mosquitoes. So we really need to work together to reduce the number of density of these mosquitoes. And has the European Union taken any sort of collective action to to reduce the spread of mosquitoes at this point? So there there are some initiatives. Um however, there aren’t particularly good ways of controlling these at a population level. You know, these these issues have been uh plaguing lots of uh low-income countries for many years. And so we really need new ways of controlling mosquitoes and new vaccines to help protect people from these new infections. When one hears this news, it’s sort of easy to imagine kind of a sci-fi horror film scenario where a mass, you know, there’s the mass spread of a deadly mosquito-born illness with the onset of climate change. How outlandish is a scenario like that? I mean, is that something that disease experts are preparing for? you know, in in in in Europe, it’s probably not going to be that kind of disaster scenario. There’s going to be increased annoyance from these things and increased disease burden from these cases. Uh but, you know, it’s unlikely that some of the more deadly diseases such as malaria will reinvade Europe. Can you talk a bit about some of the areas in Europe at this point that are the most impacted? So over the last year this report highlights that there’s been a ra large increase in the number of for example deni cases in in uh in France and so uh the number of cases that are locally transmitted. So we’re always getting u you know uh people coming in with disease but now what we’re seeing is small chains of transmission as those people spread the disease to people that haven’t got history of travel. And so what we’ve seen over the last couple of years is the number of um uh locally transmitted uh deni infections uh doubling every year. So last in 2024 there were about 84 cases in France. And I expect that to continue as as people become more aware of these infections and start testing for them more. And as you said a lot of lower income countries have been dealing with with this issue for years. What are some of the lessons uh that we in Europe could learn from them? Unfortunately, it’s that mosquitoes are very hard to control. These these these insects are very highly evolved to feed on us. And so we need really good new tools for controlling mosquitoes and the disease that they spread. And is this a phenomenon that we’re seeing perhaps in other parts of the world as well where they’re becoming more vulnerable to viruses that that didn’t used to be a threat? Yes. So both both both because of the uh the mosquito expand expanding its range but also because of this increasing temperature then you are seeing increasing areas where previously they didn’t have the disease and now they do because it’s a little bit warmer because the transmission season lasts for longer. You’re starting to see much greater cases in of these infections in many locations around the world. Can you talk about some of the other ones other than Europe? So for example, you know, in Africa, uh we have uh we have disease that spread by anophony mosquitoes that transmit malaria. And you’re seeing uh over the history place like Kenya, these uh diseases going higher and higher up the hill. And so previously high up that mountain, it was too cold for the disease to spread. Now we’re seeing uh because the temperature has risen that these mosquitoes are able to transmit the disease in these areas that previously hadn’t got any. All right, Thomas Churcher, thank you so much again for your insight this morning. That’s Thomas Churcher, a professor of infectious disease dynamics at the Imperial College London.

Europe has registered a record number of outbreaks of mosquito-borne illnesses such as chikungunya and West Nile virus this year, the EU health agency said Wednesday, saying climate change was contributing to a “new normal”. Europe is experiencing longer and more intense transmission seasons for mosquito-borne diseases, said the European Centre for Disease Prevention and Control (ECDC). For in-depth analysis and a deeper perspective, FRANCE 24’s Alison Sargent welcomes Thomas Churcher, Epidemiologist, Entomologist, Mathematical Modeller and Professor of Infectious Disease Dynamics in the School of Public Health – Faculty of Medicine at the Imperial College London.
#MosquitoBorneIllnesses #ECDC #EU

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