Five hospitals in the Siberian city of Irkutsk have been placed under quarantine after the death of a 28-year-old employee of a plague research institute, sparking concerns about a possible outbreak.
Russian health authorities insist there is no plague epidemic and officially attribute the woman's death to pneumonia of unknown origin.
Authorities are monitoring almost 200 people who are believed to have come into contact with the woman.
Hospitals and universities affected
Quarantine measures have reportedly been imposed at three municipal hospitals in Irkutsk, the Ivano-Matreninskaya Children's Hospital and a maternity hospital.
Local reports say universities in the region have cancelled classes, while an aluminium plant has introduced mandatory mask-wearing.
Officials have not confirmed that the measures are linked to plague, a lack of clarity that has fuelled concern among residents.
Death of institute employee
The woman was identified as Daria Shipilova, an employee of the Irkutsk Anti-Plague Institute.
Reports differ on how she may have become infected.
One account claims a laboratory vial containing a dangerous pathogen broke on 25 September. Another suggests she had recently returned from a work trip to Buryatia, where plague cases had reportedly been recorded near the Mongolian border.
Shipilova was admitted to hospital in Shelekhov on 29 September with pneumonia symptoms and later placed on a ventilator. She died several days later and the hospital was subsequently quarantined.
Concern despite official denials
According to local media, some healthcare workers privately suspected plague, despite the disease not being mentioned in official records.
The anti-plague institute where Shipilova worked is responsible for monitoring and researching dangerous pathogens, including the bacterium that causes plague, under strict biosecurity protocols.
What is plague?
Plague is caused by the bacterium Yersinia pestis, which was responsible for historic pandemics including the Black Death.
The disease still exists in wild rodent populations across parts of Central Asia, Mongolia and Siberia, with sporadic human infections occasionally linked to contact with infected animals.
The pneumonic form of the disease is considered especially dangerous because it can spread directly between people through respiratory droplets.
Russian authorities continue to deny that there is a plague outbreak or that the quarantine measures are connected to confirmed plague cases.
Source: CNN
