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Pneumonia of undetermined etiology - the Russian Federation

WHO Disease Outbreak News

Published

10 Oct 2026

On 2 October 2026, WHO became aware through media reports of the death of an employee of the Irkutsk Antiplague Research Institute (APRI) of Siberia and the Far East, the Russian Federation. According to these reports, the individual died on 2 October following hospitalization for severe pneumonia on 29 September, and pneumonic plague was suspected as the cause of death, following occupational exposure in laboratory settings. Following requests for verification from WHO, the National Focal Point for the International Health Regulations (2005) (NFP) of the Russian Federation confirmed the death and informed WHO that no case of plague had been registered recently in Irkutsk Oblast, that preventive and control measures had been implemented in accordance with national sanitary legislation, and that the laboratory testing of contacts detected no high-threat pathogens. The authorities also reported that no biosecurity incidents had occurred in the laboratory, contrary to reports in the media, and that there were no further case of severe pneumonia linked to this case. The NFP informed WHO that the case and all contacts had been tested for a range of microorganisms, including high-threat pathogens. Test results were negative for the tested high-threat pathogens. All contacts had been medically followed up in healthcare facilities or at home, and all remained asymptomatic throughout. Quarantine measures were instituted in the hospital where the patient was being treated. Based on the information provided by NFP, WHO has not identified evidence of ongoing transmission associated with this event. A key uncertainty remains the absence of a confirmed diagnosis in the deceased laboratory worker. WHO will continue to monitor the situation and assess any potential public health implications as further information becomes available.