Pakistan, Oct. 6 -- Russian authorities have quarantines a hospital in Siberia after a worker at a plague research institute died from pneumonia of an unknown cause. The woman worked at the Irkutsk Anti-Plague Research Institute of Siberia and the Far East. Local state television reported that she died last week at a hospital in Shelekhov, near Irkutsk.

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Authorities said extensive testing found no evidence linking her illness to pathogens associated with her work. However, unconfirmed media reports claimed she may have died from pneumonic plague. The hospital has stopped admitting and discharging patients as authorities investigate the case. Its laboratory has also suspended routin...