The next pandemic may not come from bats or birds but from material in melting ice, according to new data.
Genetic analysis of soil and lake sediments from Lake Hazen, the world’s largest High Arctic freshwater lake, suggests that the risk of viral spread – when a virus infects a new host for the first time – could be higher near melting glaciers.
The findings imply that as global temperatures rise due to climate change, it becomes more likely that viruses and bacteria locked up in glaciers and permafrost could wake up and infect local wildlife, especially as their range also approaches the poles.
For example, in 2016 an anthrax outbreak in northern Siberia that killed a child and infected at least seven others was attributed to a heat wave that melted permafrost and exposed an infected reindeer carcass. . Before that, the last epidemic in the region dates back to 1941.
To better understand the risk posed by frozen viruses, Stéphane Aris-Brosou and his colleagues at the University of Ottawa in Canada collected soil and sediment samples from Lake Hazen, close to where small, medium and large amounts of meltwater from local glaciers flowed.
Then they sequenced RNA and DNA from those samples to identify signatures that closely matched those of known viruses, as well as potential animal, plant, or fungal hosts, and ran an algorithm that assessed the risk that these viruses infect unrelated groups of organisms.
The research, published in Proceedings of the Royal Society B, suggested the risk of the virus spreading to new hosts was greatest at locations close to where large amounts of glacial meltwater have flowed – a situation that becomes more likely as the climate warms.
The team didn’t quantify how many of the viruses they identified were previously unknown – which they plan to do in the coming months – nor did they assess whether those viruses were capable of triggering a infection.
However, other recent research has suggested that unknown viruses can and do hang around in glacier ice. For example, last year researchers at Ohio State University in the United States announced that they had found genetic material from 33 viruses – including 28 new ones – in ice samples taken from the Tibetan Plateau in China. Based on their location, the viruses have been estimated to be around 15,000 years old.
In 2014, scientists from the National Center for Scientific Research in Aix-Marseille managed to revive a giant virus they isolated from Siberian permafrost, making it infectious again for the first time in 30,000 years. Study author Jean-Michel Claverie told the BBC at the time that exposing such layers of ice could be “a recipe for disaster”.
Even so, the Aris-Brosou team cautioned that predicting a high risk of spillover was not the same as predicting actual spillovers or pandemics. “As long as viruses and their ‘bridge vectors’ are not simultaneously present in the environment, the likelihood of dramatic events likely remains low,” they wrote.
On the other hand, climate change is expected to alter the range of existing species, potentially bringing new hosts into contact with old viruses or bacteria.
“The one takeaway that we can move forward with confidence is that as temperatures rise, the risk of overspill in that particular environment increases,” Aris-Brosou said. “Will this lead to pandemics? We absolutely don’t know.
It is also unclear whether the host switching potential identified in Lake Hazen is unique to lake sediments. “As far as we know, this could be the same as the host-switching probability posed by sludge viruses in your local pond,” said Arwyn Edwards, director of the Interdisciplinary Center for Environmental Microbiology at the University of Washington. ‘Aberystwyth.
However, “we urgently need to explore microbial worlds across our planet to understand these risks in context,” he said. “Two things are very clear now. First, that the Arctic is warming rapidly and that the main risks for humanity come from its influence on our climate. Second, that diseases from elsewhere find their way into vulnerable Arctic communities and ecosystems.
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