The next pandemic may not come from bats or birds, but from the stuff in the melting ice, according to new data.
Genetic analysis of soil and lake sediment from Lake Hazen, the largest deep arctic freshwater lake in the world, suggests that the risk of viral spillover – where the virus first infects a new host – is higher near melting lakes.
The findings imply that as global temperatures rise due to climate change, it becomes more likely that viruses and bacteria trapped in moles and permafrost can awaken and infect local wildlife, especially as their habitat shifts even closer to the poles.
For example, a 2016 anthrax outbreak in northern Siberia that killed a child and infected at least seven other people was attributed to a wave of permafrost that melted and exposed an infected reindeer carcass. Before this, the last riot in the country had been in 1941.
To better understand the risk posed by frozen viruses, Dr Stephane Aris-Brosou and his 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 flowed from local mountains. .
Next, the RNA and DNA in these samples were sequenced to identify signatures closely matching the virus, and potential animal, plant or fungal hosts, and ran an algorithm that estimated the chance of these viruses infecting a limited group of organisms.
The research, published in the Proceedings of the Royal Society B, suggested the risk of the virus spilling into new populations was higher in nearby areas where large amounts of glacial meltwater were flowing in – a situation more likely as the climate warms.
The team did not quantify how many viruses they identified were previously unknown – something they plan to do in the coming months – nor did they assess whether these viruses were capable of triggering infection.
However, other recent research has suggested that an unknown virus can and does reside in the ice sheet. For example, last year, researchers at Ohio State University in the US announced that they had found genetic material from 33 viruses – 28 new ones – in ice samples taken from the Tibetan region in China. Based on their location, the virus is estimated to be about 15,000 years old.
In 2014, scientists at the French National Center for Scientific Research in Aix-Massile managed to recreate a giant virus isolated from Siberian permafrost, making it infectious for the first time in 30,000 years. Study author Jean-Michel Claverie told the BBC at the time that exposing the ice sheet was such a “recipe for disaster”.
Aris-Brosou’s team also cautioned that predicting a large spillover risk was not the same as predicting actual spillovers or pandemics. “As long as their virus and the ‘bridge vector’ are not present in the environment at the same time, the likelihood of dramatic events probably remains low,” they wrote.
On the other hand, climate change is predicted to alter the impact of existing species, potentially producing new hosts in contact with old viruses or bacteria.
“The only premise that we can confidently propose is that, as temperatures rise, the risk of exposure in this particular environment increases,” said Aris-Brosou. “Will this lead to a pandemic? We do not know at all. “
It is also uncertain whether the potential for host switching that is unique to Hazen Lake is unique among sediment lakes. “For all we know, it’s the same as the likelihood of a host mutating into a virus from the local silt in your pond,” said Arwyn Edwards, director of the Interdisciplinary Center for Environmental Microbiology at Aberystwyth University.
But “we really need to explore the microbial worlds across our planet to understand these risks in context,” he said. “Two things are now very clear. First, that the Arctic is rapidly warming and there are greater risks to humanity from the influx of our climate. Second, diseases from elsewhere are penetrating into vulnerable communities and the Arctic ecosystem.”
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