Climate Change | Increased risk of new pandemics

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

Mathieu Perreault
The Press

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

Climate experts often focus, and rightly so, 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 instead be on how to respond to an unavoidable problem,” Carlson said during the conference. Wednesday press. We must ensure better monitoring of zoonoses, strengthen our health systems. »

Bats involved

Of the more than 3,300 species of mammals studied by researchers, bats are among the most involved in viral transmission, because they fly far and their very robust immune system allows them to carry many viruses without be sick. The COVID-19 pandemic likely originated with a bat virus that was 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, linked to genetic similarities between different mammals, was also modelled. “It’s a multi-year job,” Carlson said. The number of mammals studied represents about half of all species and is therefore relatively representative.

Even the Arctic is not spared

Most species-to-species virus transmission occurs in Asia and Africa, due to their rich biodiversity. “But it’s possible there will be a lot of viral crossovers in South America in the future as well,” Carlson said. For mysterious reasons, researchers believe that the phenomenon does not often occur in South America, but the very high biodiversity present there certainly lends itself to the phenomenon. Perhaps we simply lack data on the region. Very little is known about South American animal viruses. »

The passage 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, says Carlson. We are already seeing reports of massive seal mortality in the Arctic. »

Several journalists asked for 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 the first time a tiger 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 come into contact with human populations due to the expansion of cities, and the changes in human behavior in the face of climate change, according to Carlson. “Our models can be refined to better understand the real increase in risk. Bird and insect populations must also be included. »