Close to 200 people are under medical observation in Russia’s Irkutsk region after a laboratory worker at a local anti-plague research institute died following suspected exposure to plague.

Regional authorities confirmed that 189 individuals are being monitored. Alexei Tsydenov, head of the neighbouring Republic of Buryatia, said the woman had died from an unspecified form of plague. Local media had earlier reported the worker was 27 years old and had returned from a work trip to Buryatia, where an outbreak had been recorded near the Mongolian border, before falling ill with suspected pneumonic plague.

Russia’s public health watchdog Rospotrebnadzor stated that the employee had been diagnosed with pneumonia of unidentified origin and that the sanitary and epidemiological situation across Irkutsk and the nearby city of Shelekhov remained stable. The agency added that expanded testing had not detected microorganisms connected to the employee’s professional work, citing the agency’s public communications.

The White House said it was monitoring reports of the suspected case and associated quarantine measures in Russia. A Trump administration official, as cited by Axios, indicated that the administration was aware of the situation and assessing its options.

Russia’s health ministries, the World Health Organisation and the US State Department had not responded to requests for comment at the time of reporting.

Plague, caused by the bacterium Yersinia pestis, remains present in parts of central Asia and is periodically detected in rodent populations near the Russian and Mongolian border regions. Pneumonic plague, the suspected form in this case, affects the lungs and is the most serious of the three main forms of the disease. It is transmissible person to person, though outbreaks in modern settings are typically contained when identified promptly.

The situation is evolving, and the scale of the monitoring operation reflects standard precautionary protocol rather than confirmed widespread transmission. Authorities have not publicly declared an outbreak in Irkutsk itself and the epidemiological picture remains under active assessment.