The next pandemic may come not from bats or birds, but from matter in melting ice, according to new data.
Genetic analysis of soil and lake sediments from Hazen Lake, the world’s largest Arctic freshwater lake, suggests that the risk of viral shedding, where a virus infects a new host for the first time, may be higher near melting glaciers.
The findings imply that as global temperatures rise due to climate change, viruses and bacteria locked in glaciers and permafrost are more likely to awaken and infect local wildlife, particularly as their range also expands. close to the poles
For example, in 2016, an anthrax outbreak in northern Siberia that killed one 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 outbreak in the region had been in 1941.
To better understand the risk posed by frozen viruses, Dr. Stéphane Aris-Brosou and colleagues at the University of Ottawa in Canada collected soil and sediment samples from Lake Hazen, near where small, medium and large amounts of meltwater from local glaciers. .
They then sequenced the RNA and DNA in these 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 possibility that these viruses infect unrelated groups of organisms.
The research, published in the Proceedings of the Royal Society B, suggested that the risk of viruses spilling over into new hosts was greater in places close to large amounts of glacial meltwater, a situation that more likely as the weather warms.
The team did not quantify how many of the viruses they identified were previously unknown, which they plan to do in the coming months, or assess whether these viruses were capable of triggering an infection.
However, other recent research has suggested that unknown viruses can, and do, roam the glacier ice. For example, last year, researchers at Ohio State University in the US announced that they had found genetic material from 33 viruses, 28 of them new, in ice samples taken from the Tibetan Plateau in China. Based on their location, the viruses were estimated to be approximately 15,000 years old.
In 2014, scientists at France’s 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 these ice layers could be “a recipe for disaster”.
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Still, Aris-Brosou’s team cautioned that predicting a high risk of overflow was not the same as predicting actual overflows or pandemics. “As long as viruses and their ‘bridging vectors’ are not simultaneously present in the environment, the probability of dramatic events probably remains low,” they wrote.
On the other hand, climate change is predicted to alter the range of existing species, and could bring new hosts into contact with old viruses or bacteria.
“The only consideration we can confidently propose is that as temperatures rise, the risk of a spill in this particular environment increases,” Aris-Brosou said. “Will this lead to pandemics? We absolutely do not know.”
It is also unclear whether the potential for host switching identified in Lake Hazen is unique within lake sediments. “For all we know, it could be the same as the probability of host switching posed by viruses in your local pond mud,” said Arwyn Edwards, director of Aberystwyth University’s Interdisciplinary Center for Environmental Microbiology.
However, “we urgently need to explore the microbial worlds across our planet to understand these risks in context,” he said. “Now two things are very clear. First, that the Arctic is warming rapidly and that the main risks to humanity come from its influence on our climate. Second, that diseases from elsewhere are finding their way into vulnerable communities and ecosystems in the Arctic.”