New York: As many as a billion people could be newly exposed to disease-carrying mosquitoes by the end of the century because of global warming, says a new study that examines temperature changes on a monthly basis across the world.
Scientists say the news is bad even in areas with only a slight risk of having a climate suited for mosquitoes, because the viruses they carry are notorious for explosive outbreaks when they show up at the right place under the right conditions.
“Climate change is the largest and most comprehensive threat to global health security,” says global change biologist Colin J. Carlson, PhD, a postdoctoral fellow in Georgetown University’s biology department, and co-lead author of the new study. “Mosquitoes are only a part of the challenge, but after the Zika outbreak in Brazil in 2015, we’re especially worried about what comes next.”
Published in the open access journal PLOS Neglected Tropical Diseases (“Global expansion and redistribution of Aedes-borne virus transmission risk with climate change”), the research team, led by Sadie J. Ryan of the University of Florida and Carlson, studied what would happen if the two most common disease-carrying mosquitoes – Aedes aegypti and Aedes albopictus— track and move as the temperature changes over decades.
According to the World Health Organization, mosquitoes are one of the deadliest animals in the world, carrying diseases that cause millions of deaths every year. Both Aedes aegypti and Aedes albopictus can carry the dengue, chikunguyna and Zika viruses, as well as at least a dozen other emerging diseases that researchers say could be a threat in the next 50 years.
With global warming, the scientists say, almost all of the world’s population could be exposed at some point in the next 50 years. As the temperature increases, they expect year-round transmissions in the tropics and seasonal risks almost everywhere else. A greater intensity of infections is also predicted.
“These diseases, which we think of as strictly tropical, have been showing up already in areas with suitable climates, such as Florida, because humans are very good at moving both bugs and their pathogens around the globe,” explains Ryan, associate professor of medical geography at Florida.
“The risk of disease transmission is a serious problem, even over the next few decades,” Carlson says. “Places like Europe, North America, and high elevations in the tropics that used to be too cold for the viruses will face new diseases like dengue.”