Environment

'Zombie Viruses' Frozen in Fragile Permafrost Could Be Reawakened by Climate Change and Cause Global Epidemics

Sure, it could happen—but don't lose any sleep over it.

Photo Credit: ImageFlow/Shutterstock

Are zombie pathogens on the rise due to global warming, as has been reported? Are they a threat to humankind?

As reported in Scientific American, dozens of people and thousands of reindeer in Siberia were infected by anthrax last year, potentially as a result of thawing disease pathogens. It was the region's first outbreak in 75 years.

The report explained that the potential dangers of newly emerged infection from permafrost greatly depend on the robustness of a given infection. Some can persist for many years, but extreme cold could also cause microorganisms to perish.

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Any time a new strain of virus or bacteria emerges from mutation, animal reservoirs or permafrost, humans could be infected. In order to cause a global pandemic, the pathogen would need several characteristics: It would have to be easily transmitted, such as by coughing or sneezing; have no available treatment or cure; be a virus (as antibiotics are ineffective against viruses); and be unique from other current viral pathogens, so our immune systems would not recognize it.

One potential example is a unique strain of influenza, a virus that causes a contagious respiratory illness that infects the nose, throat and sometimes the lungs, and can sometimes cause death.

Here's how it could work: Influenza also infects birds. If a bird who died of influenza 1,000 years ago thawed, it could be picked up by a dog out for a walk with its owner. If the dog brought the bird back to the owner in its mouth, jumped up and licked her owner's face, that creates the possibility of transmission. A virus could infect the human; the human gets sick and goes to the local doctor's office and coughs on a nurse and a doctor. The nurse and the doctor catch the virus without realizing it. Both continue to see patients even after they develop a cough. Many of the patients develop a cough about a week later. One of these patients hops on a plane to go to a wedding. It's a long flight and air is recycled on planes, so the virus spreads to many other passengers. Once the virus hits a major airport, it can cross the globe in less than 24 hours.

The chance of this happening is very low, but it is possible.

I wouldn't lose sleep over the microbes that are now thawing from permafrost. In order to be a real threat, the pathogens need to survive the long freeze and come in contact with a human. Since most permafrost areas are sparsely populated, the overall risk is quite low.

While reports of dangerous microbes being released from thawing permafrost aren't as scary as some scientists have reported, it's a situation that deserves more study.

Elizabeth Greguske is an assistant professor of biology at Saint Anselm College in Manchester, New Hampshire.