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A billion people may be newly exposed to mosquito vectors of disease by the end of the century because of global warming, says a new study that examines temperature changes every month in the world.
Scientists say the news is bad, even in areas where there is little chance of a mosquito-friendly climate, as the viruses they carry are notoriously prone to explosive outbreaks when they come to life. good place and in good conditions.
"Climate change is the biggest and most comprehensive threat to global health security," says Colin J. Carlson, a climate change biologist, PhD student, and postdoctoral researcher in the Department of Biology at Georgetown University. -author of the new study. "Mosquitoes are only part of the challenge, but after the zika epidemic in Brazil in 2015, we are particularly concerned about the aftermath of the events."
Published in the open access journal PLOS Neglected Tropical Diseases ("Global Expansion and Redistribution of Risk of Transmission of Aedes-Transmitted Virus with Climate Change"), the research team led by Sadie J. Ryan of the United States. University of Florida and Carlson studied what would happen if the two most common mosquito vectors of disease – Aedes aegypti and Aedes albopictus – follow and move as the temperature changes over the decades.
According to the World Health Organization, mosquitoes are one of the most deadly animals in the world, carrying diseases that cause millions of deaths each year. Aedes aegypti and Aedes albopictus can both be infected by dengue, Chikunguyna and Zika viruses, as well as by at least a dozen other emerging diseases that researchers say could pose a threat in the 50s. coming years.
According to scientists, with global warming, almost all of the world's population could be exposed at some point over the next 50 years. As the temperature increases, they expect year-round transmissions in the tropics and seasonal hazards almost everywhere else. Greater intensity of infections is also expected.
"These diseases, which we consider strictly tropical, are already occurring in climate-friendly areas like Florida, because humans are very effective at moving insects and their pathogens around the world," says Ryan, an badociate professor. Medical geography in Florida.
"The risk of disease transmission is a serious problem, even in the coming decades," says Carlson. "Regions like Europe, North America and the high tropical highlands, which were too cold for the virus, will face new diseases like dengue."
More severe climate change would result in less population exposure to the Aedes aegypti mosquito. However, in the areas with the greatest climatic increase, particularly West Africa and South-East Asia, the Aedes albopictus mosquito is expected to experience significant reductions, particularly in Southeast Asia and South Africa. West. This mosquito carries dengue, chikunguyna and zika.
"Understanding the geographic changes in risk really puts that in perspective," says Ryan. "Even if we see numbers change and think we have the answer, imagine a world too hot for these mosquitoes."
"This might seem like good news, bad news, but it's bad news if we end up in the worst climate change scenario," Carlson said. "Any scenario in which a region becomes too hot to transmit dengue fever is one where we also face different but equally serious threats in other areas of health."
The research team looked monthly at temperatures to predict the risks between 2050 and 2080. The modeling did not predict what type of mosquito would migrate, but rather to create a climate in which their propagation would not be prevented.
"From what we know about moving mosquitoes from one area to another, 50 years, it's a long time and we expect a significant spread of both types." of insects, especially Aedes aegypti, which thrive in urban environments, "says Carlson.
"It's only a study to begin to understand the future challenges we face in the face of global warming," Carlson says. "We have a Herculean task ahead of us. We must determine the pathogen by pathogen, region by region, when problems arise in order to be able to plan a global response to health. "
In addition to Ryan and Carlson, the authors of the study include Erin A. Mordecai of Stanford University and Leah R. Johnson of Virginia Polytechnic University and the University of Toronto. State.
This work was funded by: The National Science Foundation (DEB-1518681, DEB-1641145 and DEB-1640780), Centers for Disease Control and Prevention (1U01CK000510-01), Southeast Regional Center for Excellence on vector-borne diseases: the Program Portal, the Stanford Woods Institute of the Environment, and the Stanford Center for Global Health Innovation.
The authors do not report any potential financial conflict of interest related to the work described.
Source: Georgetown University
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