Health authorities in Siberia’s Irkutsk region have placed nearly 200 people under medical observation after a laboratory worker died from plague, according to media reports and a statement by a regional leader Friday.

Alexei Tsydenov, head of the neighboring republic of Buryatia, confirmed that the woman had died from an unspecified form of plague. Irkutsk officials had previously described the illness only as a “particularly dangerous infection.”

Citing information from Russia’s consumer safety watchdog Rospotrebnadzor and Buryatia’s government, Tsydenov said the woman had not visited his republic and that her infection was unrelated to the region.

“There are no plague outbreaks in the republic, including in areas bordering Mongolia,” he wrote on social media.