What the WHO found

The World Health Organization said on Saturday that it still does not know what caused the death of a young worker at a laboratory in Irkutsk, Siberia, that focuses on plague and other illnesses. In its first full Disease Outbreak News since the case emerged earlier this month, the agency cited initial, unconfirmed reports suggesting pneumonic plague, a severe form of pneumonia that spreads from person to person but has high recovery rates when detected and treated in time. Russian health officials had conducted more than 5,500 tests and found no evidence of any dangerous pathogenic microorganisms, according to the WHO. Russia also told the agency that no plague cases had recently been recorded in Irkutsk Oblast and that no biosafety incident had occurred at the institute.

The worker and the days before her death

The employee, 28-year-old Daria Szypiłowa, worked at the institute in Irkutsk Oblast, according to Polish reporting on the case. She was admitted to hospital on 29 September with symptoms of severe pneumonia and died three days later. Earlier local media reports said that on 25 September she broke a test tube containing a pneumonic plague pathogen, a claim that the Russian side has not accepted. The WHO learned of the case from media reports on 2 October, and after her death authorities placed about 200 people under observation and quarantine.

Russia's denial and the disputed second case

Russia has denied that any second case exists. The WHO continues to refer to "a purported second case" which it earlier attributed, in emailed explanations to The Associated Press, to two tabloid news outlets in Britain and Serbia that cited unspecified reports in Russia. Laboratory tests on people who had contact with the infected worker showed no pathogens posing a high risk, according to Russian authorities. WHO director-general Tedros Adhanom Ghebreyesus had earlier said the organization could not complete a full risk assessment because Russia had not supplied complete data and the cause of the worker's death had not been established.

What remains open

The WHO has called for a continued investigation and has sent official questions to Russian authorities. US President Donald Trump said this week that Russia was giving Americans "a bit of information" but that he wanted more, adding that Russians assured him they had things "under control". The agency's request for more data is set out in its statement.

“Additional clinical, epidemiological and laboratory information, including confirmation of the diagnosis in the deceased laboratory worker, is required to improve confidence in the assessment.”

The diagnosis in the deceased worker has not been confirmed, and the cause of her death remains unknown.