“The coming decades will not only be hotter, but also worse. » It is with this shocking proposal that Gregory Albury of the Department of Biology at Georgetown University in Washington sums up the work he has done with Colin Carlson and other members of the American non-governmental organization EcoHealth Alliance to study the effects of climate change on the risk of transmission of the virus between different animal species. In this study, published Thursday, April 28 in the journal Nature, the authors estimate, using sophisticated models and databases, that at least 15,000 new interspecies transfers should occur by 2070. “We have demonstrated a potentially devastating new mechanism for the emergence of diseases that can threaten the health of animal populations, mainly with consequences for our health.” emphasizes Gregory Albury.
Due to climate change, many animal species will travel hundreds of miles or more in the coming century to survive, carrying their parasites and pathogens with them. These large-scale movements will trigger numerous encounters, so far unprecedented, between species that previously evolved in different environments, creating as many opportunities as possible for the transfer of viruses and other potentially harmful 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, barriers to encounter will disappear, emphasizes Jean-Francois Guégan, director of research at the Institute for Development Studies and at the National Research Institute of Agronomy, Food and the Environment, who was not involved in the study. This “species tectonics” will cause more and more viral or bacterial transmissions between species, sometimes almost unpredictable. »
Hot spots in Africa, Asia and Europe
The extent of this phenomenon will largely depend on the compatibility of these viruses with their potential new hosts, as well as areas of overlap between the life pools of different species. In any case, the authors of the study caution that these viral exchanges are largely unexplored and may eventually cause zoonoses, that is, the transmission of some of these viruses to the human population.
Thus, scientists have identified various “hot spots”, places particularly favorable for cross-species viral contact and transmission, which will largely coincide with high population density in 2070, especially in the Sahel, the Ethiopian Highlands and the Rift Valley, India, East China, Indonesia. and the Philippines. Some European territories have also been identified. Newly emerging pathogens such as the Usutu virus, which has markedly wiped out the thrush population in Europe. “show that these populations can remain vulnerable despite increased surveillance and access to health care”, warn authors.
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