Europe is “very closely” monitoring a suspected case of pneumonic plague in eastern Russia, following the death of a lab worker, a European Commission spokesperson said Monday.

“We are aware of the reports concerning the laboratory incident in Russia, seemingly involving a pathogen-causing plague,” European Commission spokesperson Eva Hrncirova told reporters. “We are in touch with our experts from [the] European Center for Disease Prevention and Control, and we monitor very closely what is going on.”

A 28-year-old employee at the Irkutsk Anti-Plague Institute of Siberia and the Far East fell ill and died on Friday from what Alexei Tsydenov, head of the neighboring republic of Buryatia, said could be a case of pneumonic plague.

Rospotrebnadzor, Russia’s consumer watchdog, has not confirmed the exact cause of death, saying only that the employee died from “pneumonia of unknown etiology.” More than 200 people have been placed under observation following her death.

“The sanitary and epidemiological situation in the Irkutsk region, the cities of Irkutsk and Shelekhov is stable,” Rospotrebnadzor said in a statement, adding that “a special set of measures was organized and carried out” in connection with the death.

It added that no microorganisms associated with her professional activities were identified in the sample from the deceased patient.

Igor Kobzev, governor of the Irkutsk region, where the institute is located, said authorities had identified, examined, and placed under medical supervision all the people who had come into contact with the patient. No other employee at the anti-plague institute has visited the doctor over the past few days, he added.

Information sharing

U.S. officials have told Radio Free Europe that they are monitoring the situation, and urged Russian authorities to “share accurate information quickly and openly.”

Secretary of State Marco Rubio told reporters Monday the U.S. knew “whatever the Russians have provided.” “I don’t think its cause for alarm but it is cause for focus and cause for just keeping an eye on it and we’re doing that,” he added.

A spokesperson for the World Health Organization said the United Nations health agency was aware of the “reports” of the death and it was attempting to verify the details.

In accordance with International Health Regulations, “WHO is in contact with the Russian health authorities to verify the event, its circumstances, the laboratory tests underway, and their results, the rationale for contact-tracing and the health status of contacts, as well as any potential international public health implication,” a WHO spokesperson told POLITICO.

“Based on unofficial information available, the public health risk to the general population appears to be low,” the spokesperson said, adding that the risk assessment will be updated once more information is available.

Asked about the communication with Russia, Hrncirova said the EU has “channels [on] how to get the information.” “We obviously would like to recall that timely and transparent reporting and access to reliable epidemiological and laboratory finding is essential,” she added.

Treatment

Plague is an infectious disease caused by the bacterium Yersinia pestis, usually found in small mammals and their fleas, according to the WHO. It has been absent from Europe for more than 50 years, said Hrncirova, though it continues to appear in the Americas, Africa and Asia.

Pneumonic plague is the most contagious form as it can pass from person to person via respiratory particles. Its incubation is relatively short, with symptoms — including shortness of breath and coughing — appearing usually within 24 hours after infection. Pneumonic plague is always fatal if left untreated.

“Pneumonic plague is particularly serious because it means the infection has reached the lungs,” said Simon Clarke, associate professor in cellular microbiology and public engagement in science at the University of Reading.

Plague is treatable with common antibiotics, if diagnosed early. Hrncirova could not immediately say whether Europe has sufficient stocks of antibiotics.

“Countries have their stocks of antibiotics, and then we have reserves on the European level. But at this stage, I am not able to give you any numbers,” she said.

But “until more details emerge, it is difficult to assess whether this represents an isolated case, an occupational exposure, or evidence of wider transmission,” Clarke added. “Any outbreak of plague is worrying, but this can be controlled and stopped with appropriate surveillance and control measures.”

This story has been updated.