Russia is investigating a suspected laboratory accident after a 28-year-old worker at a plague research institute in Siberia died following a severe illness.

The incident took place at the Irkutsk Research Anti-Plague Institute in Shelekhov, near Irkutsk, where the woman worked as a laboratory technician.

According to reports from local and independent Russian media, the worker may have accidentally broken a test tube containing plague bacteria while working at the facility. She later developed severe pneumonia and died on October 2.

However, Russian health authorities have not confirmed that plague caused her death or that a laboratory accident involving the pathogen took place.

Rospotrebnadzor, Russia’s consumer and public health watchdog, said the woman had been diagnosed with pneumonia of unknown origin. It added that further testing found no microorganisms linked to her professional activities.

The agency also said the sanitary and epidemiological situation in Irkutsk and Shelekhov remains stable.

Despite the lack of confirmation, authorities have introduced precautionary measures and are monitoring people who may have had contact with the woman.

Nearly 200 people have reportedly been placed under medical observation, while restrictions have been introduced at medical facilities linked to the case. Officials have said identified contacts are being tested and monitored.

The case has raised particular concern because the institute specializes in studying plague and other dangerous infectious diseases.

Plague is caused by the bacterium Yersinia pestis. Its pneumonic form affects the lungs and can spread between people through respiratory droplets. It can become serious quickly but is treatable with antibiotics when treatment begins promptly.

For now, there is no publicly confirmed evidence of a wider plague outbreak in the region. Russian authorities continue to describe the local epidemiological situation as stable.