Over the next fifty years, Climate change It will lead thousands of viruses to jump from one type of mammal to another, according to A study Posted in Nature on Thursday. Mixing viruses between animals may increase one’s risk of transmitting to humans and causing a new pandemic, the researchers said.
Scientists have long warned that global warming may increase the disease burden. malaria, for example, is expected to spread as the mosquitoes that carry them expand their range in warming regions. But climate change may also give rise to entirely new diseases, by allowing pathogens to migrate to new host species.
“We know that species are on the move, and when that happens, they will have these opportunities to share viruses,” said Colin Carlson, a biologist at Georgetown University and one of the authors of the new study.
To understand what this engagement would look like, Dr. Carlson and his colleagues built a computer model of the potential ramifications in an increasingly warming world. Researchers are beginning to project how thousands of mammals might change their ranges with climate change between now and 2070.
As temperatures rise, many species are expected to spread farther from the smoldering equator to find more comfortable habitats. Others may move over hillsides and mountains to find cooler elevations. When different species come into contact for the first time, viruses may be able to infect new hosts.
To understand the prospects for a successful new infection, researchers set out to build a database of viruses and their mammalian hosts. Some viruses have been found in more than one species of mammal, which means they have jumped the species barrier sometime in the past.
Using a computational technique called machine learningResearchers have developed a model that can predict whether two host species share the virus.
The researchers found that the more geographically two species overlapped, the more likely they were to share the virus. That’s because the hosts were more likely to encounter each other, giving their viruses more opportunities to move between them.
Dr. Carlson and his colleagues also showed that closely related species were more likely to share the virus than distant relatives. This is probably because closely related mammals have similar biochemistry. A virus that is adapted to exploit one species is more likely to thrive in a relative. He may also be able to evade an immune system similar to the one he has already adapted to.
These findings enabled Dr. Carlson and his colleagues to make predictions about what might happen when mammal species come together for the first time in a hotter world.
Of the 3,139 species studied, the researchers predicted more than 4,000 cases in which viruses would pass from one species to another. In some cases, a single virus makes the jump. But the models also predicted that multiple viruses carried by one species would spread to the other.
The researchers were unable to determine which viruses would pass between species. What counts, they argued, is the sheer scale of what’s to come.
“When you try to predict the weather, you’re not predicting individual raindrops,” said Christopher Tresos, an ecologist at the University of Cape Town and one of the authors of the new study. “You expect the same clouds.”
Rachel Baker, a disease ecologist at Princeton University who was not involved in the study, said the research was an important step forward in understanding how climate change is affecting the world’s dangerous viruses. Previous studies focused on single virusesunlike surveying the entire world.
“It’s great progress,” she said. “We want to know as soon as possible if there is a link between climate change and the spread of pathogens.”
The researchers found that bats in Southeast Asia would be particularly vulnerable to these transmissions. As of now, many bat species in that region are restricted to small ranges and don’t come into much contact with each other. But as the planet warms, these bats will quickly fly to the right climates and encounter new species.
These results may be particularly ominous for humans. When viruses move to new host species, they evolve — and can evolve in ways that make them more susceptible to infection. The Corona Virus The one that caused SARS in 2002 originated in Chinese horseshoe bats and then jumped to another species — possibly raccoon dogs sold in Chinese animal markets — before infecting humans.
In February, scientists launched two studies Confirming that Covid arose through a similar chain of events, with the Corona virus transmitted from bats to wild mammals sold in markets in Wuhan before infecting humans.
“We think this is something that could happen a lot as a result of the interspecific transmission events we would expect,” said Gregory Alberi, a disease ecologist at Georgetown University and one of the authors of the new study.
When researchers looked at where mammals might end up in 2070, they found another reason to expect new human pandemics: They wouldn’t migrate to wildlife refuges. “It turns out that these are all the places where we built cities,” Dr. Carlson said.
Rare rodents that have little contact with humans today may transmit a virus to raccoons, who live comfortably in urban areas. “This opens a whole new avenue for this virus to spread to humans,” Dr. Alberi said.
Dr. Kristen Johnson, an epidemiologist at the University of California, Davis, who was not involved in the study, cautioned that such a broad model could not explain details that might have a significant impact on individual viruses. “We need field studies on a local basis to understand the effects of climate on species movements and the risks of disease transmission,” she said.
The fallout from the climate may start well before 2070. After all, the planet is already 1.1°C warmer than it was in the nineteenth century. In their computer model, the researchers found that there had already been enough climate change to start mixing viruses, even though their model doesn’t allow them to point to specific viruses that have jumped.
“The amount of warming we saw was enough to start the movement,” Dr. Carlson said.