The World Health Organization (WHO) is seeking additional information from Russia regarding the death of a laboratory worker from suspected pneumonic plague, as well as reports of a second employee with pneumonia of unknown cause, its chief said Wednesday.
Tedros Adhanom Ghebreyesus said in a post on the US social media platform X that the worker at the Irkutsk Antiplague Research Institute died on October 2 after being hospitalised with “severe pneumonia.”
He said the WHO has requested additional information to clarify the cause of the worker’s severe pneumonia, the pathogen that prompted the public health measures and reports of a second employee with pneumonia of undetermined cause.
“Timely, complete and transparent information sharing” is essential to clarify conflicting reports and accurately assess potential public health risks, he added.
Initial media reports suggested pneumonic plague following an alleged “accidental laboratory exposure,” he said.
Russian authorities said no plague cases had recently been registered in Irkutsk Oblast, in response to a WHO verification request under the International Health Regulations.
Authorities told the WHO that an epidemiological investigation was conducted, preventive and control measures were implemented and identified contacts were monitored and tested.
No high-threat pathogens were detected among the contacts, and medical observation of all identified contacts has been completed, according to Russian authorities.
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.
