Climate change will accelerate viral transmission between species

“The coming decades will not only be hotter but sicker. » It is with this shocking phrase that Gregory Albery, from the Department of Biology at Georgetown University in Washington, summarizes the work he has carried out, with Colin Carlson and other members of the American NGO EcoHealth Alliance. , on the consequences of climate change on the risks of viral transmission between different animal species. In this study published Thursday, April 28 in the journal Naturethe authors estimate, using complex models and databases, that at least 15,000 new interspecies transmissions are expected to occur by 2070. “We have demonstrated a potentially devastating new mechanism for the emergence of diseases that could threaten the health of the animal population, with, for the most part, ramifications for our health,” emphasizes Gregory Albery.

Driven by climate change to move to survive, many animal species will travel a hundred or more kilometers in the coming century, taking their parasites and pathogens with them. These large-scale movements will cause many hitherto unprecedented encounters between species that previously evolved in separate environments, creating as many possibilities for the transmission of viruses and other potentially dangerous bacteria between animals. “The interesting point of this study is that it shows that new coexistences of species will occur on a large spatial scale, the barriers of encounter will disappear, emphasizes Jean-François Guégan, director of research at the Institute of Research for Development and at the National Research Institute for Agronomy, Food and the Environment, who did not contribute to the study. This “species tectonics” will cause more and more viral or bacterial transmissions between species, sometimes almost unpredictable. »

Hotspots in Africa, Asia and Europe

The extent of this phenomenon will largely depend on the compatibility between these viruses and their potential new hosts, as well as the areas of overlap of the life basins of the different species. In any case, the authors of the study warn that these viral exchanges are, for the most part, not studied and may eventually cause zoonoses, that is to say the transmission of some of these virus to the human population.

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Scientists have thus identified different “hotspots”, places particularly conducive to interspecies viral encounters and transmissions, which will largely coincide with a high population density in 2070, particularly in the Sahel, the Ethiopian highlands and the Rift Valley, l India, Eastern China, Indonesia and the Philippines. Some European territories have also been identified. Recently emerged pathogens such as the Usutu virus, which notably decimated the population of blackbirds in Europe, “show that these populations may still be vulnerable, despite increased surveillance and access to care”, warn the authors.

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