Climate change | Increased risk of new pandemics

According to a new study, by 2070 there will be 15,000 crosses of a virus from one animal species to another. However, such viral transfers sometimes lead to an adaptation of the virus to humans. This means there are likely to be more new epidemics or even pandemics.

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Mathieu Perreault

Mathieu Perreault
The press

“It’s a process that’s already underway,” said Gregory Albery of Georgetown University, one of the co-authors of the study published Thursday in the journal. Nature† “It’s one of the aspects of global warming that’s unavoidable. It even occurs in the most optimistic scenarios of the Intergovernmental Panel on Climate Change (IPCC). †

Climate experts often, and rightly, focus on what can be done to minimize climate change, says another co-author, Colin Carlson also of Georgetown, who is part of the IPCC team. “But in the case of zoonoses — diseases that pass from animals to humans — and pandemics, the focus should be on how to respond to an unavoidable problem,” Carlson said at the conference. We need to ensure better monitoring of zoonoses and strengthen our health systems. †

concerned bats

Of the more than 3,300 mammal species studied by researchers, bats are among the most involved in viral transmission, as they fly far and their very robust immune systems allow them to carry many viruses without getting sick. The COVID-19 pandemic likely originated with a bat virus transmitted to a wild animal sold in Chinese markets, possibly the pangolin.

Ebola and HIV are other viruses that jumped from one mammal to another before mutating enough to infect humans.

The study of Nature modeled the possible changes in the range of these mammals depending on climate change. The probability of a virus passing from one species to another, coupled with genetic similarities between different mammals, was also modeled. “It’s a multi-year job,” Carlson said. The number of mammals studied represents about half of all species and is therefore relatively representative.

Not even the Arctic is spared

Most species-to-species virus transmission occurs in Asia and Africa, due to their rich biodiversity. “But it’s possible that there will also be a lot of viral crossovers in South America in the future,” Carlson said. For mysterious reasons, researchers believe that the phenomenon is uncommon in South America, but the very high biodiversity present there certainly lends itself to the phenomenon. Maybe we’re just missing data on the region. Very little is known about South American animal viruses. †

The transmission of viruses from one species to another will also pose a problem for wildlife. “In the Arctic, the loss of sea ice will facilitate the transmission of viruses between marine mammals. It could devastate some populations, Carlson says. We are already seeing reports of massive seal deaths in the Arctic. †

Several journalists asked about specific examples of possible viral transmission. But the researchers did not want to be more specific. “If I talk about a possible event that will happen when a tiger first encounters a deer, but it doesn’t happen, it diminishes the credibility of the science,” Carlson said.

The next step is to better model the behavior of animals when they interact with human populations due to the expansion of cities and the changes in human behavior in the face of climate change, Carlson said. “Our models can be refined to better understand the true increase in risk. Bird and insect populations should also be included. †

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  • 10,000
    Number of virus species that can infect mammals

    SOURCE : NATURE

    6%
    Proportion of mammalian species carrying a virus present in another species

    SOURCE : NATURE

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