On Oct. 5, 2026, Reuters reported that a laboratory worker at a plague research institute in ‌Siberia fell ill and died in undisclosed circumstances, prompting authorities to quarantine dozens of people and the head of Russia’s health watchdog to fly to the Irkutsk region. The death has sparked public health fears on social media, but the authorities said on Monday the situation was under control.

Plague is endemic to Siberia, location of the first known prehistoric human outbreak, as the bacterium that causes it, Yersinia pestis, is ​present among the small wild mammals in its vast wilderness and their fleas. It is rare for Russians to fall ill with plague, however, though cases occur every year in other parts of the world — notably Africa.

Plague comes in three forms affecting different parts of the body. Pneumonic plague, an infection of the lungs, prompts the ​patient to cough out infectious airborne droplets. If identified quickly, it can be treated with antibiotics. But if left untreated, it can be fatal ​in one to six days.

Local media have named the laboratory worker who died as Darya Shipilova, a 28-year-old employee at the Irkutsk Anti-Plague Research Institute of Siberia and the Far East.There were ‌conflicting reports ⁠about how and where she fell ill, but the authorities said she had died of pneumonia of as-yet unestablished origin. According to Russian media ⁠reports, about 200 people who had been in contact with the dead woman were quarantined, parts of the hospital in the town of Shelekhov where she died were cordoned off and an aluminium plant told its workers ​to wear masks.

Russia’s health watchdog, Rospotrebnadzor, told state media the institute had not found evidence of any accidents involving the handling of pathogens after rumours spread on social media that the woman had dropped a test tube containing live bacteria. Rospotrebnadzor, in a later statement quoted by the TASS news agency, said officials in Irkutsk Region had ​found two cases ⁠of COVID and two cases of rhinoviruses among people who had been in contact with her. No other cases of infectious diseases were noted.