Climate change threatens human life in many ways but one of the less obvious could be a rise in pandemics.
A warming climate could release ancient pathogens, such as bacteria and viruses, that have been frozen in permafrost in the polar regions for millennia, Jean-Michel Claverie tells ABC RN's Future Tense.
"We know for certain that bacteria can remain dormant but alive for probably up to 500,000 years in permafrost. And so at that point, this is the very beginning of Homo sapiens. Our species was just emerging [at that time]," says the emeritus professor of medicine at France's Aix Marseille University.
Dr Claverie and his team of researchers recently published their findings on seven ancient viruses found in Siberia's permafrost. One was almost 50,000 years old and still infectious.
He says scientists don't yet know exactly how ancient diseases could impact living species today – animals or humans. In 2021, it was reported that more than 100 ancient strains of bacteria found in Siberia's permafrost were resistant to antibiotics.
The professor says that if an ancient disease – like a virus that was lethal for a woolly mammoth – did spread across the world, it could have dangerous implications for humans.
"This is, I think, very dangerous because mammoths are [genetically] very close to elephants. [And] elephants are [genetically] very close to humans."
Rising exposure
Dr Claverie says the risk is complex because even if an ancient pathogen is released from permafrost, it needs a host to infect. In inhospitable polar regions, he says, this isn't much of a concern at the moment.
But with a warming climate, these regions may become more hospitable, opening them up to an increased human presence.
"The danger is not so much the fact that those particles are released, but the fact that there will be more exposure to those particles by humans or animals," Dr Claverie says.
More humans in these areas risk new diseases and potentially future pandemics.
Dr Aaron Bernstein is the director of the Center for Climate, Health, and the Global Environment at Harvard University's School of Public Health in Massachusetts in the US.
He says our increasing proximity to animals is increasing zoonotic spillover, which is when pathogens evolve to infect humans.
It's been said that there could already be up to 850,000 viruses that have the potential to evolve from infecting animals to also infecting humans.
Dr Bernstein says deforestation and the wild animal trade are increasing the risks of zoonotic spillover.
"A huge [risk] is livestock and the fact that we have just immense concentrations of animals now in many places around the world, with relatively limited, if any, biosurveillance for potential spillover [being] a real challenge for us. "
The cost of pandemics
There are countless discussions underway about how to respond to future pandemics, particularly after the devastating impact of COVID-19.
However, Dr Bernstein says the focus should be on preventing the spread of potentially zoonotic diseases in the first place.
Responsive measures like vaccines may be effective at reducing harms, but Dr Bernstein doesn't believe they're the best approach to limiting the spread of disease.
He says if you prevent a pathogen from emerging in the first place, "then you get immense benefits where you don't worry about the efficacy of a vaccine, or people taking it, and the ethics that come up with who gets the vaccine and who has access to it".
He says there are also global cost benefits to focusing on prevention.
In October 2020, it was estimated the total cost of the COVID-19 pandemic was roughly US$16 trillion ($24.2 trillion) in the US alone.
Other virus outbreaks have also been costly. It's been estimated that the 2014 West African Ebola outbreak had a total cost of US$53.19 billion ($80.5 billion), while the 2003 SARS epidemic cost up to US$100 billion ($151.39 billion).
"If you look at all of the viruses that have caused 10 or more deaths in an outbreak roughly over the past century that are zoonotic … you're looking at [a cost of] roughly potentially like half a trillion dollars a year."
Dr Bernstein says there are other wider financial costs to a pandemic.
"If you look at the economic losses – meaning, how much did these emerging infectious diseases contribute to economic decline – that's another $300 billion a year every year from these diseases," he says.
"That [cost] gives you a sense of how much we're losing and how much might be justified in spending and prevention.
"But the question really comes down to: How effective do these interventions need to be?"
Working together will help
Dr Bernstein says one way to prevent these viruses early on could be more collaboration between sectors that don't regularly cross paths, for example, between animal conservationists or veterinarians working with public health officials.
"The folks who know the most about how animals live and how to conserve them have not been effectively engaged with the folks who are charged with addressing human disease risk," he says.
He's not alone. Others have said more collaborations between governments, scientific bodies and non-government organisations to ensure the health of the planet and its inhabitants – sometimes known as the "One Health" concept – could help prevent pandemics.
Dr Christine Prat, the director of operations at the European Virus Archive (EVA), is one of them.
"It is reported that 60 per cent of emerging diseases in the world are zoonosis … so in terms of virus research and pandemic preparedness and response, it's very important to have the smoothest collaboration across research organisations and in different countries," she says.
The EVA often shares virus strains with researchers from the world's scientific communities, which can be very helpful when new diseases emerge.
"During the Zika outbreak, it was very striking to us to see that scientists not only order the Zika virus [from the EVA] but they also needed to compare it to other clinically or epidemiologically relevant viruses," Dr Prat says.
"Those scientists ordered a lot of arboviruses at the same time, because the studies needed those kinds of comparisons," she adds.
"So we strongly believe that having an archive – the largest possible – is a strong pillar in pandemic preparedness."
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