Employee of a Russian Anti-Plague Lab Dies of Pneumonia, Sparking Concerns Over the Disease Behind the Black Death. Here’s What to Know

No official cause of her pneumonia has been confirmed, and Russian health officials say that none of the deceased individual’s close contacts tested positive for the plague. Pneumonic plague is a rare, deadly form of the disease

Sara Hashemi | Daily Correspondent

October 7, 2026 10:00 a.m.

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A 28-year-old laboratory technician at the Irkutsk Anti-Plague Research Institute of Siberia and the Far East in Russia fell ill and died of pneumonia last week, sparking concerns that she may have had the rare but deadly pneumonic plague.

The exact circumstances of the employee’s sickness are still unclear as conflicting reports have emerged from the country. One Russian news outlet claimed that the worker, named Darya Shipilova, may have contracted pneumonia from a broken test tube containing plague samples, while another said that she contracted the disease after a trip to Thailand. There have also been concerns that the woman worked in a bioterrorism unit, though this has not been confirmed.

Dozens of people have been quarantined in the region of Siberia, although the country’s national health agency said that none of Shipilova’s close contacts tested positive for the plague, according to an October 6 statement from the World Health Organization (WHO).

No cause of death has been confirmed at this point, and the agency estimates the risk to the global public is low.

“Maybe it’s going to come out that she died from something unrelated and it was just a coincidence” that she worked in an anti-plague lab, says Lisa Morici, a microbiologist and immunologist in the Tulane University School of Medicine, to Berkeley Lovelace Jr. and Erika Edwards at NBC News.

Here’s what you should know about the disease at the center of the story.

What is the plague?

The plague is an infection caused by the bacterium Yersinia pestis. The most common forms of plague are bubonic, pneumonic and septicemic. According to the Centers for Disease Control and Prevention (CDC), pneumonic plague is the most serious form of the disease, and it’s the only one that can spread from person to person. However, it’s also the least common in nature.

Pneumonic plague occurs when Y. pestis spreads to the lungs of a person with untreated bubonic or septicemic plague, or when a person inhales droplets from a person or animal infected with pneumonic plague. Symptoms include fever, headache, weakness and a quickly developing pneumonia with shortness of breath, chest pain, cough and even bloody or watery mucus.

The disease progresses rapidly—symptoms can start as soon as one day after infection, according to the WHO. And once they set in, the illness can be fatal within 18 to 24 hours.

“It’s the one that’s so frightening because it can kill so quickly,” Morici tells NBC News. That’s also why it’s categorized as a “Category A” bioterrorism agent by the CDC.

How is it treated?

A roughly two-week course of antibiotics can treat the plague, reports CNN’s Jen Christensen. The sooner patients start the regimen, the better. Physicians might also provide patients with supplemental oxygen and fluids, as well as encourage rest.

If left untreated, the death rate of pneumonic plague is almost 100 percent.

Although a vaccine exists, neither the CDC nor the WHO recommend routine plague vaccination for people who are not regularly exposed to the plague. (High-risk people include laboratory personnel who work with Y. pestis.)

Should you be worried?

“This case does not cause undue concern,” says Michael Osterholm, an epidemiologist at the University of Minnesota, to Stephanie Soucheray of CIDRAP News, which is published by the university. “We would like more information, of course.”

Osterholm adds that if the case had occurred in a “friendly” nation, the public probably wouldn’t have jumped to claims of bioterrorism. Plague infections happen regularly around the world, including in the United States. About seven cases of the disease are reported each year in the country, per the CDC. They mostly occur in the Southwest, where the environmental conditions allow Y. pestis’s flea hosts to thrive.

The WHO emphasizes in the statement that the risk of pneumonic plague is low outside of the Irkutsk region—where the research institute is located—and moderate to low within it. The agency will continue working with Russian health authorities to assess the situation as more information becomes available.

Sara Hashemi is a science writer and fact-checker currently based in New York City. Her work has appeared in Sierra, The Body, Maisonneuve magazine and more.