The US has said it is monitoring developments relating to a suspected case of pneumonic plague in Russia, which has imposed sweeping quarantine measures in Siberia over the incident while insisting there has been no outbreak.
On Monday, US secretary of state Marco Rubio said Washington was watching the matter “closely” after an employee at Siberia’s Irkutsk Anti-Plague Research Institute was admitted to hospital outside the city on September 29.
“It seems there was a worker at the lab that was infected and there was concern that could have spread,” Rubio said. “Like anything else, if something like that gets out, it could quickly spread so we are watching and monitoring it closely.”
Daria Shipilova, 28, died two days later from what public health watchdog Rospotrebnadzor described as “pneumonia of unknown” origin. Local media reported that pneumonic plague may have been the cause of death.
Marco Rubio says Washington is watching the matter “closely” amid reports of a suspected plague case in Russia
If confirmed, it would be Russia’s first case of plague in a decade. Europe has not seen a human plague outbreak since the immediate aftermath of the second world war.
However, Rubio cautioned that he did not think the incident was “cause for alarm”.
Russian authorities have not confirmed a recorded plague infection. The public health watchdog said tests on samples from Shipilova did not detect micro-organisms “connected with her work”.
Speaking to reporters on Monday, Kremlin spokesperson Dmitry Peskov urged them “not to listen to rumours about a plague outbreak” and to “rely on Rospotrebnadzor’s statement”.
But the scale of the Russian authorities’ response suggested they were treating the situation as exceptional. Irkutsk region governor Igor Kobzev said in a social media post on October 2 that he held an “emergency meeting” with Rospotrebnadzor over “a suspected case of a highly dangerous infectious disease”.
Rospotrebnadzor was “carrying out the full range of anti-epidemic measures”, while everyone who had been in contact with Shipilova had been “placed under medical observation”, he added.
As many as 200 people were placed under observation, according to local media. The inpatient section of the Shelekhov district hospital was quarantined alongside several hospitals in Irkutsk, the independent People of Baikal outlet reported.
Only the quarantine at the Shelekhov hospital has been officially confirmed.
Staff at Shipilova’s institute were also isolated inside the building, “sleeping on chairs”, RFE/RL’s Siberia.Realities reported, citing sources.
On October 3, the head of the Irkutsk aluminium factory wrote on his Telegram channel that employees must wear face masks because of “contradictory information about plague”, but quickly edited the post to remove the mention of the disease.
According to the pro-Kremlin Telegram channel Mash, which has close ties to Russia’s law enforcement agencies, Shipilova had recently returned from a work trip to the country’s Buryatia region near the border with Mongolia.
Mongolia regularly records plague cases, with 17 confirmed instances reported to the World Health Organization between 2019 and 2025.
But Alexei Tsydenov, head of Russia’s Republic of Buryatia, said the woman who had “possibly died of plague” had not entered the region.
The US state department told the FT that “many details have not been confirmed” about the matter, adding that “we encourage Russian authorities to share accurate information quickly and openly”.
“Plague is a known disease and is treatable with common antibiotics, especially when treatment starts early,” the official added.
Shipilova joined the Irkutsk institute in 2022 and had served as a researcher in its plague microbiology department since 2023. This spring, she was listed among the authors of a presentation on antibacterial drug susceptibility of the plague-causing bacterium Yersinia pestis.
The last confirmed plague case in Russia was in 2016, in a tiny Altai Republic settlement near the border with Mongolia, when a 10-year-old boy contracted the disease after contact with a marmot that his grandfather killed while hunting. The boy survived after receiving treatment.
The authorities did not dispute the diagnosis, isolated the boy’s contacts, disinfected affected areas and carried out an extensive campaign against marmot hunting.
Additional reporting by James Politi