Almost 200 people have been placed under medical observation in Russia after a worker at an anti-plague research institute in eastern Siberia died of what many have been reporting as a form of plague on Thursday.
The employee was hospitalized with severe pneumonia last Tuesday before dying in the hospital on Thursday, according to local news, which wrote on Friday that the 28-year-old Darya Shipilova was suspected to have fallen ill with the plague after returning from a work trip to Buryatia.
Early Russian reports wrote that Shipilova had contracted the pneumonia after breaking a vial of plague bacteria.
Alexei Tsydenov, head of the nearby Republic of Buryatia, where the woman had reportedly visited, stated that she had died from an unspecified form of plague.
Tsydenov later modified his statement to say she had possibly died from the plague.
Employee diagnosed with 'pneumonia of unspecified etiology', Russian watchdog says
Russia's public health watchdog, Rospotrebnadzor said on Sunday that the employee had been diagnosed with "pneumonia of unknown etiology," in a statement on Sunday, adding that no microorganisms linked to her work had been found.
According to Rospotrebnadzor, extensive anti-epidemic measures were put in place, including "identifying the widest possible circle of people who had been in contact with the patient, inpatient medical observation, and daily laboratory testing."
Aside from two cases of Covid-19 and two cases of rhinovirus infection (the most frequent cause of the common cold), no other infectious agents were found, according to the official watchdog agency.
However, many still suspect, as initial reports indicated, that Shipilova contracted pneumonic plague, one of the three kinds of plague caused by the Yersinia pestis bacterium, the same one behind the infamous Black Death that affected Europe in the mid 1300s.
Pneumonic plague occurs when the bacteria attacks the lungs, resulting in severe respiratory symptoms, including shortness of breath and coughing, which can turn bloody.
Pneumonic plague is also the only form that can be transmitted between humans through inhaling respiratory particles from someone who is sick.
While pneumonic plague can be fatal if left untreated, if detected and treated within 24 hours of symptom onset, recovery rates are high, according to the World Health Organization.
Trump 'concerned' about plague while Kremlin warns against rumors
US President Donald Trump said that he was concerned about the suspected plague outbreak when asked by reporters on Monday, saying that it was "a big problem for Russia."
"Well, I hate to see them having it," Trump said. "It's a rough disease."
Trump also said that the US would be willing to provide help if needed.
"We'll help," Trump said. "Anybody that has that kind of a problem, we're always willing to help."
US Secretary of State Marco Rubio also told reporters that US authorities were monitoring the situation on Monday, warning that "if something like that gets out it could quickly spread."
"We're watching and monitoring it closely," he said.
Kremlin spokesman Dmitry Peskov urged Russians to listen to Rospotrebnadzor's report rather than "various rumors and speculation."