India, Oct. 5 -- A death inside a Siberian anti-plague research institute has turned into a growing public health mystery in Russia. Daria Shipilova, a 28-year-old laboratory worker in the Irkutsk region, died after developing severe pneumonia, while authorities placed nearly 200 people who may have had contact with her under medical observation. The incident has attracted international attention because of her workplace and reports that she may have been exposed to live bacteria.

However, Russia has not officially confirmed that Shipilova died from plague. Regional authorities have described the case as involving a "particularly dangerous infection", while the federal health watchdog has reportedly referred to pneumonia of unknown aetio...