After the COVID pandemic, we’re all a little jumpy when it comes to new disease outbreaks. So it’s understandable that the death of a lab technician working at a plague research institute in Siberia has put everyone on high alert. But while there’s still much we don’t know about that case, there is another health threat brewing in Russia that deserves more attention and alarm.

The details of the suspected plague infection are murky. Local media coverage suggested that 28-year-old Darya Shipilova may have contracted pneumonic plague after an accident at her workplace, though those reports have not been verified. Russian authorities have said that about 200 of her contacts were quarantined. Pneumonic plague is a severe infection that occurs when the bacterium Yersinia pestis infects the lungs. Without treatment, it’s nearly always fatal.

Officially, Shipilova’s death has been attributed to pneumonia of “unknown” origin, and Russian authorities have told the World Health Organization that no plague case had been registered in the region. The WHO has requested further details, and US President Donald Trump has said he has a call scheduled with Russia’s Vladimir Putin to discuss the incident.

The WHO says it doesn’t have enough information to conduct a full risk assessment and that Russia has been too slow to respond to its inquiries, calling the delay “not okay.” The opacity of the country’s response is worrying — not least because the potential plague is not Siberia’s only public health concern.

The one I’m most worried about lies in the region’s permafrost, where remnants of previous pandemics are preserved in the cold. There, smallpox virus DNA was detected in a 300-year-old mummy and influenza virus RNA was found in the lung of a body lodged in the earth since 1918. Scientists have now been able to revive pathogens that have lain dormant in the permafrost for tens of thousands of years. Some are fascinating but not threatening, such as the giant viruses that can only target single-celled amoebas. Others are relatives of common human pathogens such as Staphylococci (staph bacteria) and Campylobacter (the most common cause of diarrhoeal diseases). Although we have drugs that should be able to defend against these familiar foes, there is a surprisingly high prevalence of antibiotic-resistant genes among bacteria in the frozen ground. Even scarier are the viruses and bacteria that may have played a role in the demise of Neanderthals or mammoths, and would be new to us today.

Of course, none of this would be a problem if our climate was stable. But human-caused climate change is warming the Arctic up to four times faster than the rest of the planet. The permafrost is rapidly thawing, raising the risk that a Pandora’s Box of ancient pathogens will be unleashed. The danger is heightened by the growing industrialization of the region and resulting increase in migrant workers, who raise the risk of spreading any outbreak to less remote parts of the world.

As far-fetched as the appearance of a zombie pathogen might sound, consider that thawing Siberian permafrost after a hot, dry summer led to a 2016 anthrax outbreak that killed a 12-year-old boy and more than 2,300 reindeer.

In 2023, scientists from France, Germany and Russia published a paper warning that the health risks of melting permafrost are very real and warrant further study. But with most of the world’s permafrost located in Russia, Putin’s invasion of Ukraine has complicated research partnerships and information sharing.

And as the lack of detail surrounding the suspected plague death demonstrates, it’s not at all clear that Russia would be forthcoming about any risk emerging from the permafrost.

As Tedros Ghebreyesus, director-general of the WHO, wrote in an X post Thursday about the investigation of Shipilova’s death: “Timely, complete and transparent information sharing under the International Health Regulations is essential to clarify conflicting reports and enable an accurate assessment of potential public health risks.” That’s as true for zombie pathogens as it for plagues.

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This column reflects the personal views of the author and does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

Lara Williams is a Bloomberg Opinion columnist covering climate change.

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