The World Health Organization has said Russia reported no recent plague cases in the Irkutsk region after a laboratory worker died of severe pneumonia, following reports of suspected pneumonic plague linked to an alleged lab exposure.

WHO Director-General Tedros Adhanom Ghebreyesus said the agency is in contact with Russian health authorities and has sought further information from them to determine the cause of the illness and clarify reports of a second employee with pneumonia.

The laboratory worker died on October 2 after being hospitalised with severe pneumonia. She worked at the Irkutsk Anti-Plague Research Institute in Siberia, a facility that specialises in plague and other high-threat infectious diseases.

Russian health authorities have since said that the woman's death was linked to pneumonia of unknown origin and that no plague had been detected among those who came into contact with her.

An epidemiological investigation was carried out and preventive and control measures were implemented, the WHO said. Contacts of the deceased worker were identified, tested and placed under medical observation.

Around 200 people were reportedly placed under observation as a precaution following the death. Russian authorities have said that testing among the contacts did not identify plague or other dangerous infectious pathogens. Reuters reported that about 60 per cent of those placed under quarantine had subsequently been released.

The WHO has stressed that the reported death should not be treated as evidence of a confirmed plague outbreak.

"Timely, complete and transparent information sharing under the International Health Regulations is essential to clarify conflicting reports and enable an accurate assessment of potential public health risks," Tedros Adhanom Ghebreyesus said.

"No high-threat pathogens have been detected among the contacts," the WHO said, adding that medical observation of all identified contacts had been completed.

According to information provided by Russian health authorities to the WHO under the International Health Regulations, no case of plague had recently been registered in Irkutsk Oblast.

WHO has offered technical support to Russian authorities and said it remains in contact with them.

Why the reports sparked concern

The Irkutsk incident drew international attention because the deceased worker was employed at an anti-plague research institute and initial reports suggested pneumonic plague following a possible laboratory accident.

Pneumonic plague is the most severe form of plague and can spread between people through respiratory particles. It can progress rapidly and be fatal if treatment is delayed. However, plague is treatable with antibiotics when diagnosed early.

WHO's latest fact sheet, updated on September 29, says plague is caused by Yersinia pestis and is usually associated with small mammals and their fleas. Human infection can occur through infected flea bites, contact with infected tissues or inhalation of respiratory particles from someone with pneumonic plague.

The agency says human plague remains endemic in some countries, with most cases reported to WHO between 2019 and 2025 coming from the Democratic Republic of the Congo and Madagascar.

For the Irkutsk incident, however, WHO has said the available information does not establish a confirmed plague case or a wider outbreak.

WHO spokesperson Christian Lindmeier said the public health risk to the general population appeared to be low based on the information available.

The focus now remains on determining what caused the laboratory worker's severe pneumonia and resolving conflicting reports surrounding the incident. WHO has said further information from Russian authorities is needed before a definitive assessment can be made.



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