New health threat? Pathogens frozen in permafrost resurface as Earth heats up

In the unlikely scenario where a virus is able to infect mammals and humans, it could be disastrous, say experts

By Taran Deol
Published: Tuesday 20 December 2022
New health threat? Pathogens frozen in permafrost resurface as Earth heats up
Photo: iStock Photo: iStock

A warming planet is resulting in the loss of the Earth’s cryosphere — parts of the planet where water is permanently frozen such as glaciers and ice sheets, and this could be resurrecting trapped pathogens, giving rise to potential public health threats, find a new study. 

While our understanding about microbes confined in glaciers has been developing over the past thirty years, a recent preprint published in the preprint repository bioRxiv last month shed some more light. 

It analysed samples from seven different ancient Siberian permafrost sites and pieced together preliminary characterisations of 13 new viruses. 

The study was led by European researchers who have added to the only existing literature on live viruses in the cryosphere: Two reports published in 2014 and 2015. In the former, published in the peer-reviewed journal Proceedings of the National Academy of Sciences (PNAS), pithovirus was identified. In the latter, also published in PNAS, mollivirus was identified

The motivation for the research was to develop a more realistic understanding of the viruses that persist in glaciers and ice sheets. An absence of information doesn’t indicate there is no threat at all, the authors wrote. 

Noting that these unknown viruses will eventually be released into the atmosphere, it remains to be seen how their interaction with outdoor conditions such as ultraviolet light, oxygen and heat unfold, and their potential to infect a suitable host. 

The viruses studied so far only infect amoeba and are of no real threat to humans or animals.

Another route of a potential viral threat could be the thawing of dead people who possibly died of an infection. A 300-year-old frozen mummy from Siberia was found to contain the variola virus that causes smallpox, a 2014 Nature study found. 

Bodies exhumed from Alaska’s permafrost contributed to understanding the 1918 Spanish flu virus genome, a 2007 study published in the journal of Antiviral Therapy revealed. 

In the unlikely scenario where a virus is able to infect mammals and humans, it could be disastrous, the researchers warned, adding:

Each new virus, even related to known families, almost always requires the development of highly specific medical responses, such as new antivirals or vaccines. There is no equivalent to ‘broad spectrum antibiotics’ against viruses, because of the lack of universally conserved druggable processes across the different viral families. 

In conclusion, the authors noted that the risk of viruses is “bound to increase in the context of global warming when permafrost thawing will keep accelerating, and more people will be populating the Arctic in the wake of industrial ventures”. 

While comparatively little research has been done on viruses trapped in permafrost, bacterias in similar conditions are better understood. In 2016, Russia’s Yamal Peninsula witnessed an anthrax outbreak, which killed more than 2,000 reindeer, infected dozens of people and, reportedly, also an unnamed boy. 

Temperatures in June, July and August that year were 20–100 per cent higher than the preceding three decades. “Abnormally high ambient temperature in the summer of 2016 contributed to the thawing of permafrost and viable Bacillus anthracis (anthrax-causing bacteria) spores could have become exposed to the surface,” a 2021 study published in the journal Frontiers noted. Such incidents date as far back as 1848 and are unlikely to cause a pandemic. 

“We can reasonably hope that an epidemic caused by a revived prehistoric pathogenic bacterium could be quickly controlled by the modern antibiotics at our disposal,” the preprint argued. This is because the antibiotics target cellular structures (such as ribosomes) and metabolic pathways (transcription, translation or cell wall synthesis) conserved during the evolution of all bacterial phyla, the authors added. 

Read more: Scientists revive approximately 50,000-year-old ‘zombie virus’ from frozen lake in Russia

The research paper also made an interesting observation about antibiotic-resistance genes being prevalent in permafrost. Paul Hunter, professor of medicine at the University of East Anglia, noted this isn’t particularly surprising since “many antimicrobial resistance genes have evolved from soil organisms that predate the antimicrobial era”. 

The planet is warming and the 10 per cent of Earth’s surface that is covered with ice and snow is slowly melting away. In fact, the Arctic is warming at a faster pace than the rest of the panet. 

There is an urgent need to strengthen our understanding of frozen pathogens, and expand our surveillance measures. “It is critical to complement the surveillance of ‘animal reservoirs’ of pathogens (both natural and accidental) with the study of ‘ecosystem reservoirs’,” a 2021 study published in the journal Environmental Sustainability said. Therefore, studies of microorganisms in glaciers and permafrost could help us to take a glimpse into the future, it added. 

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