Diseases like malaria and dengue fever will likely spread ever farther afield in coming decades.
Mosquitoes are some of the most dangerous animals in the world. Their bites cause millions of deaths every year from infectious diseases like malaria, dengue, Zika, chikungunya and yellow fever. Owing to climate change, mosquitoes are going to acquire even more power to spread diseases.
As the planet warms, mosquitoes learn to survive colder seasons, and thus quickly increase in numbers and spread to more temperate climates. According to a new paper published in PLOS Neglected Tropical Diseases, this may cause over a billion of new infections by the end of the century.
The scientists wanted to see how increasing temperatures would influence the spread of viruses by Aedes mosquitoes, which are among the worst vectors for diseases. To do so, they modeled the spread of viruses under different warming scenarios, comparing results of who is currently at risk with various future scenarios that might await us in 2050 and 2080.
“This study is a bit of a numbers game: with 7 billion people on Earth, who’s most at risk now? Who’s at risk in a generation? We don’t know where mosquitoes will be in the future. What we can do is say where they might be able to transmit viruses if they show up,” says Colin J. Carlson, a biologist at Georgetown University and co-author of the paper.
People in developing countries who are already badly affected are going to get even more plagued by mosquitoes, with the eastern part of sub-Saharan Africa to be most exposed to risks of malaria and dengue fever. Experts already have to focus on preventive measures, developing necessary health infrastructure and monitoring the spread of those diseases.
The diseases are also likely to spread because of people who travel a lot and so when they are bitten by mosquitos carrying a virus, they can then easily spread it abroad after being bitten by mosquitos there that can spread the disease further. As climate change is global, highly mobile global populations from countries like the U.S. are going to experience increased vulnerability to diseases, as exemplified by previous epidemics of dengue fever in Hawaii in 2001 and in Florida in 2009.
While out of thousands of mosquito species only a few are actually able to spread a certain disease, researchers so far were able to model the future for only two of them. With more research the problem might turn out to be much larger than previously thought, say researchers.