A 28-year-old laboratory technician at a Russian research institute dedicated to studying plague and other infectious diseases has died of a mysterious illness, prompting authorities to impose quarantine measures and place nearly 200 people under observation.
The researcher worked at the Irkutsk Research Anti-Plague Institute of Siberia, located in the town of Shelekhov near the Mongolian border. According to Rospotrebnadzor, the Russian agency that handles infectious disease, she was diagnosed with pneumonia of “unknown” origin .
Maxim Modin, the mayor of the Shelekhovsky district, said authorities are implementing a “comprehensive set of anti-epidemic measures.” The inpatient facility where the worker was treated has been placed under quarantine, and several departments have stopped discharging or admitting patients. Other hospitals in the region have also been closed .
According to Rospotrebnadzor, “no micro-organisms associated with the employee’s professional duties were detected in samples taken from the patient” . There have been no cases of infectious diseases reported among institute staff over the past 10 days, and all of the employee’s recent contacts are being tested and examined.
Unofficial reports, including by the independent regional news outlet Liudi Baikala, have said that nearly 200 people are under observation.
The head of the neighboring republic of Buryatia, Alexei Tsydenov, said earlier that the employee died “possibly from the plague.” He also noted that “there are no plague outbreaks” in Buryatia.
Pneumonic plague is one of three types of plague caused by the bacterium Yersinia pestis. According to the World Health Organization, pneumonic plague is the most virulent form, with an incubation period that can be as short as 24 hours. It can be transmitted from person to person through respiratory particles, and untreated cases are always fatal .
Plague has a case-fatality ratio of 30% to 60% for the bubonic type, and is always fatal for the pneumonic and septicaemic kinds when left untreated. However, antibiotic treatment is effective against plague bacteria, and early diagnosis and treatment can save lives .
The Irkutsk Anti-Plague Institute employs around 95 researchers and is a major research and public health facility responsible for monitoring and preventing outbreaks of high-risk bacterial and viral infections across Siberia and Russia’s Far East.
An aluminum plant near the laboratory instructed staff to wear masks as a precautionary measure. The director of the Irkutsk Aluminum Plant, Artem Fominikh, urged calm and noted that “there are many rumors and conflicting reports circulating.”
A former head of Rospotrebnadzor, Gennady Onishchenko, said on Friday that the infection in the Irkutsk region is “most likely not the plague, but even if confirmed, there will be no spread of this disease.” He told state news agency TASS that the onset of cold weather would likely prevent transmission.
A US State Department spokesperson told CNN that the United States is aware of the possible death due to pneumonic plague in Russia and is “monitoring the situation closely with the CDC and our other interagency partners.” The spokesperson encouraged Russian authorities to “share accurate information quickly and openly.”
The US Department of Health and Human Services said the CDC is closely monitoring the situation in Russia, and that the “safety and security of U.S. citizens is our highest priority.”
Plague is found on all continents except Oceania. Between 2019 and 2025, most human cases reported to WHO occurred in the Democratic Republic of the Congo and Madagascar.
