MOSCOW, Russia – The United States is closely monitoring the situation in Russia after a laboratory researcher at an anti-plague institute died from pneumonia of unknown origin, amid reports she may have been exposed to pneumonic plague.
US Secretary of State Marco Rubio said Washington was watching developments but cautioned against alarm.
“We’re watching and monitoring it closely. I don’t think it’s cause for alarm, but it is cause for focus and a cause just to keep an eye on it,” Rubio said.
The 28-year-old female researcher worked at the Irkutsk Anti-Plague Research Institute of Siberia and the Far East.
Russia’s consumer welfare service said on Sunday that she died from “pneumonia of unknown etiology”, meaning the exact cause had not been established.
Russian authorities have not confirmed that the researcher contracted pneumonic plague.
They said there was no evidence that her illness was caused by any of the pathogens she worked with at the institute.
Nearly 200 Contacts Being Monitored
Reports citing a regional official said nearly 200 people who had been in contact with the researcher were being monitored.
Maksim Modin, mayor of the Shelekhov municipal district near Russia’s border with Mongolia, said the inpatient facility where the researcher was treated had been closed and placed under quarantine.
Russian authorities said the sanitary and epidemiological situation in Irkutsk region, including the cities of Irkutsk and Shelekhov, remained stable.
The Kremlin had not immediately responded to requests for comment.
WHO Warns Pneumonic Plague Can Spread Rapidly
The World Health Organisation (WHO) describes pneumonic plague as the most virulent form of plague and warns that it can trigger severe outbreaks through person-to-person transmission via respiratory particles.
The incubation period can be as short as 24 hours, with symptoms developing rapidly.
Symptoms may include severe respiratory problems, shortness of breath and coughing, sometimes accompanied by blood-stained mucus.
The WHO says untreated pneumonic plague can become fatal within 18 to 24 hours after symptoms begin.
However, the disease can be effectively treated with antibiotics when diagnosed and treated early.
Experts Say Wider Outbreak Appears Unlikely
Dr Ashish Jha, who served as White House COVID-19 response coordinator from 2022 to 2023, said pneumonic plague was “very hard” to spread from person to person.
Jha said more information and transparency from Moscow would be necessary to determine the circumstances surrounding the case.
If the incident proves to be an isolated case and there are no further deaths, he said, “it will probably end there”.
Jha also said questions surrounding possible biological weapons programmes would be more concerning and should be understood as part of the wider investigation.
Ian Jones, professor of virology at the University of Reading, described the incident as appearing to be a rare laboratory accident that was unlikely to develop into a wider outbreak.
“Although it is true that pneumonic plague is directly transmissible, the contacts of the primary case are known and can be treated if they show any sign of infection,” Jones said.
He noted that plague remains present in parts of the world, including Russia, but said modern living conditions, access to antibiotics and the ability to identify contacts had significantly reduced its potential for widespread transmission.
Plague Cases Still Reported Globally
The WHO said that between 2019 and 2025, 10 countries reported more than 3,800 suspected human plague cases.
Six of those countries reported confirmed cases, with most occurring in the Democratic Republic of the Congo and Madagascar.
The agency said 423 deaths were recorded among the reported cases.
For now, Russian authorities have not established that the Irkutsk researcher’s death was caused by pneumonic plague, while health officials continue monitoring people who may have been exposed.
