A 28-year-old laboratory worker has died of suspected plague in Russia’s Irkutsk region, triggering a large quarantine operation. Nearly 200 of her contacts have been placed under medical observation.

Daria Shipilova worked at the Irkutsk Anti-Plague Research Institute of Siberia and the Far East. Russian media reported that she told doctors she broke a test tube containing live bacteria on September 25 while collecting samples. She was admitted to hospital in Shelekhov on September 29 with severe pneumonia and died on October 1 after two days on a ventilator.

Officials first spoke only of a “particularly dangerous infection”. The head of neighbouring Buryatia later publicly named the disease as plague. Russia’s chief sanitary doctor Anna Popova flew about 2,600 miles from Moscow to take charge of the response.

The hospital in Shelekhov has been quarantined and about 100 of its staff isolated. A mask order is in effect in the town, some public events in Irkutsk were cancelled, and an investigation into possible safety violations has been opened.

Governor Igor Kobzev said the contacts under observation are asymptomatic and their initial tests have come back negative. Russia’s last registered plague case was in 2016.