There are concerns over potential international transmission after a 28-year-old laboratory technician died from suspected pneumonic plague in eastern Siberia.
It has triggered hospital lockdowns, regional transit concerns, and calls for airport screening in the UK.
Daria Shipilova, an employee at the Irkutsk Anti-Plague Research Institute of Siberia and the Far East, fell critically ill in late September and died at a district hospital in Shelekhov.
Russian news outlet People of Baikal reported on Friday that the dead woman may have contracted pneumonic plague from a broken test tube.
Russia’s public health consumer watchdog, Rospotrebnadzor has publicly denied any pathogen release or workplace link.
The health watchdog said on Tuesday (6) that no cases of plague had been detected among anyone who had come into contact with a Siberian plague institute laboratory worker who died last week, and locals said their lives had barely been disrupted.
The death has prompted international concern, including from US President Donald Trump.
Rospotrebnadzor said in a statement that no infectious diseases had been reported among the staff of the same plague research institute in Irkutsk over the past 10 days and that extensive testing had found no microorganisms in the deceased woman's body linked to her work.
"A comprehensive set of anti-epidemic measures was immediately organised and implemented in full in accordance with public health legislation," the watchdog said.
"This included identifying the widest possible circle of individuals who had been in contact with the patient and arranging for them to be placed under medical observation in hospital with daily laboratory tests."
Trump on Monday (5) described the situation as a "big problem for Russia" and offered to help.
US Secretary of State Marco Rubio said on Tuesday it was incumbent on Moscow to share more information, and said Washington was monitoring "very closely".
"I think it's incumbent upon Russia to obviously share more information with the world," Rubio said during a trip to Iceland.
In an apparent response to Trump's offer, Rospotrebnadzor on Tuesday (6) announced that Russia was prepared to assist the United States in combating its own outbreaks of infectious diseases.
Russia, it stressed, was "prepared to provide the US side with specialists, laboratory equipment and highly effective diagnostic and preventive tools".
The World Health Organization in Geneva said on Tuesday (6) that Russia had told it there were no cases of plague in the city of Irkutsk.
The update said Russia had launched an epidemiological investigation into a "case of community-acquired pneumonia" in an employee at the Irkutsk institute, and had identified contacts and made arrangements for medical monitoring and laboratory testing.
"Test results showed no presence of dangerous infectious disease pathogens in any of the contacts," the update said, according to WHO.
Based on the information currently available, the United Nations health agency "estimates the risk to be moderate to low for Irkutsk", spokesman Christian Lindmeier told a press briefing in Geneva.
He said the risk was low for Russia as a whole, and very low for the rest of Europe.
Nonetheless, he stressed that they were monitoring the situation closely and seeking to verify the event and the laboratory tests.
Plague is a bacterial disease that can occur in several forms, including pneumonic plague, which is the most contagious type and can be transmitted by respiratory means. Bubonic plague is transmitted by infected fleas.
Pneumonic plague, which causes lung failure, can be fatal if not treated early, according to WHO.
