Russia denies reports of second case linked to Siberian plague lab

Russian health authorities on Thursday denied reports of a second infection linked to a worker at a plague research institute in Siberia who died last week.

The country's health regulator said it had checked all contacts of the dead woman, in a statement carried by Russian news agencies. None showed signs of infectious disease, and nearly 5,000 lab tests found no dangerous pathogens.

The case drew international attention when the woman, who worked at the Irkutsk Anti-Plague Research Institute of Siberia and the Far East, died on October 2 after being hospitalized with pneumonia of unknown cause. Russian authorities said that tests found no microorganisms linked to her work. Reports that she died of plague remain unconfirmed.

Pneumonic plague occurs when plague bacteria infect the lungs. WHO notes this form is especially contagious and "can trigger severe epidemics through person-to-person transmission via respiratory particles."

According to WHO, pneumonic plague "can be fatal within 18 to 24 hours of disease onset if left untreated, but common antibiotics for enterobacteria can effectively cure the disease if they are delivered early."