In the last decade, Jean-Michel Claverie, a professor of economics and bioinformatics at Aix-Marseille University in France, has been hunting for “zombie viruses”. These are dormant microbes that could still infect hosts after being frozen for hundreds or thousands of years.
Most recently, he uncovered the oldest ever recorded zombie virus that dates back approximately 48,500 years ago. This is what these previously frozen viruses could mean for human health.
Scientists have uncovered a 48,500 year old virus that could be the oldest ever discovered. The virus was found embedded in Siberian permafrost. The discovery potentially reveals that ancient viruses can stay frozen for long periods of time without losing their ability to infect hosts.
For safety, Claveria has only studied viruses that can infect amoeba, or single-celled organisms. He and his team isolated 13 viruses from samples of Siberian permafrost.
When placed in petri dishes with amoeba, these viruses were all able to worm their way into the organisms. Using radiocarbon dating of the permafrost samples, they determined that the youngest of the viruses was 27,000 years old, but the oldest was frozen 48,500 years ago — setting a new record for the resuscitation of a zombie virus.
What Is Permafrost?
Permafrost is defined as ground that remains below 32 degrees Fahrenheit for two or more years. It is found in parts of Alaska, Canada, and Siberia, where it covers up to a fifth of the land area.
The permafrost is extremely important because it stores huge amounts of carbon. As the permafrost thaws due to climate change, this stored carbon is released into the atmosphere and contributes to global warming.
How Does Permafrost Preserve Things So Well?
Permafrost is a very cold environment. The ground is frozen solid, and there is no oxygen or bacteria in it to cause decay.
This process is called mummification, allowing organic material to remain intact for thousands of years. Many examples of preserved animals and plants found in permafrost have been carbon dated to be over 50,000 years old.
What Do These Zombie Viruses Mean For Human Health?
The Arctic is getting warmer and defrosting, exposing previously frozen microbes and other creatures to the surface environment. The researchers’ findings raise concerns about what this could mean for animal and human health in light of climate change.
“We view these amoeba-infecting viruses as surrogates for all other possible viruses that might be in the permafrost,” Claverie told CNN. “We see the traces of many, many, many other viruses, so we know they are there. We don’t know for sure that they are still alive. But our reasoning is that if the amoeba viruses are still alive, there is no reason why the other viruses will not be still alive, and capable of infecting their own hosts.”
While the viruses that Claverie and his team have studied are only capable of infecting amoeba, this doesn’t mean that other human and animals infecting viruses haven’t also been discovered. Scientists have discovered traces of human-infecting viruses in permafrost.
For example, in 1997, scientists exhumed the body of a woman buried in permafrost in Alaska. They took a sample of her lungs, which contained the DNA of the flu strain that caused the 1918 Spanish flu pandemic.
Some Evidence of Zombie Viruses Being Problematic For Humans Already Exists
In July and August of 2016, an anthrax outbreak in Siberia affected dozens of humans and more than 2,000 reindeer. Scientists have linked this outbreak to the deeper thawing of the permafrost during unusually hot summers, which allowed old spores of Bacillus anthracis to resurface from old burial grounds or animal carcasses.
“You must remember our immune defense has been developed in close contact with microbiological surroundings,” Birgitta Evengård, professor emerita at Umea University’s Department of Clinical Microbiology in Sweden told CNN. “If there is a virus hidden in the permafrost that we have not been in contact with for thousands of years, it might be that our immune defense is not sufficient. It is correct to have respect for the situation and be proactive and not just reactive. And the way to fight fear is to have knowledge.”
How Likely Is It That A Zombie Virus Could Infect Humans?
Though the researchers say we should study these viruses in order to be proactive about the situation, they don’t want to cause imminent panic- after all, many things are still unclear. They don’t know how long or how well a thawed virus would survive, especially given that current-day conditions are much different than they were tens of thousands of years ago.
On top of that, in order to survive, a virus needs a host. These viruses trapped in permafrost are in places where very few, if any, humans actually live. Once thawed, how will they even find a host? Additionally, not all viruses cause disease. Some are benign while others are even beneficial.
Still, there is reason for concern. After all, as the Earth warms, it is not just viruses that will potentially spring back to life. Newly possible industrial opportunities in these arctic places will inevitably attract more people. This increases the likelihood that a human could come in contact with a zombie virus, and from there, we could potentially have problems.
“We’re really unclear as to how these microbes are going to interact with the modern environment,” she said Kimberley Miner, a climate scientist at the NASA Jet Propulsion Laboratory at the California Institute of Technology in Pasadena, California. “It’s not really an experiment that I think any of us want to run.”
The best course of action, according to the experts?
Do our best to keep the permafrost as frozen as possible. This means continuing our efforts to fight back against climate change. The colder the arctic remains, the better.
Sources:
“Scientists have revived a ‘zombie’ virus that spent 48,500 years frozen in permafrost.” CNN Katie Hunt. March 8, 2023.
“An Update on Eukaryotic Viruses Revived from Ancient Permafrost.” Pubmed. Jean-Marie Alempic, et al. February 2023.
“What Is Permafrost?” Climate Kid