The World Health Organisation (WHO) says it has found no evidence of ongoing transmission linked to the death of a Russian laboratory worker who developed severe pneumonia, although the cause of her illness remains unknown.
In an outbreak report published on Saturday, the WHO said Russian authorities had reported negative test results for plague and other tested high-threat pathogens in the deceased worker and her identified contacts.
The worker, an employee of the Irkutsk Antiplague Research Institute of Siberia and the Far East, died on October 2 after being hospitalised with severe pneumonia on September 29.
Her death raised concerns about a possible pneumonic plague infection following media reports of potential occupational exposure at the laboratory.
However, Russian authorities said she died from pneumonia of undetermined aetiology after testing negative for a range of dangerous pathogens.
Nearly 200 People Monitored After Death
According to the WHO, nearly 200 people were reportedly placed under medical observation following the death, prompting precautionary measures, including contact tracing and laboratory testing.
Russian authorities reported that more than 5,500 laboratory tests had been conducted, with none detecting high-consequence or dangerous pathogenic microorganisms.
The seven-day medical monitoring of identified contacts, which included daily laboratory testing, was completed on Friday, according to information provided to the WHO.
“The 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,” the WHO said, citing a report from Russia’s National Focal Point.
WHO Says Cause of Illness Remains Unknown
The WHO said it had not received information identifying the agent responsible for the fatal illness, leaving the precise cause undetermined.
Although a laboratory-associated exposure could not be completely ruled out, the available information did not indicate infection with the tested high-threat pathogens or identify additional linked cases.
Russian authorities also said the worker had been vaccinated against the high-threat pathogens she handled as part of her job. She had not travelled outside Irkutsk Oblast during the two weeks before her symptoms began.
Officials further reported that investigations had found no laboratory biosafety or biosecurity incidents at the institute, disputing media reports suggesting otherwise.
The case attracted international attention, with the United States and the WHO seeking further information from Russia amid uncertainty surrounding the suspected infection.
No Travel or Trade Restrictions Advised
In its latest assessment, the WHO said the absence of a confirmed diagnosis limited its ability to independently assess the public health risk.
The organisation said additional clinical, epidemiological and laboratory information was needed to establish the cause of the illness and strengthen confidence in its assessment.
The WHO said it would continue monitoring the situation but did not recommend any travel or trade restrictions related to the incident.
The findings indicate that no ongoing transmission linked to the case has been identified, but the cause of the worker’s death remains unresolved.
