Russian authorities have quarantined a hospital and are monitoring contacts of an employee at a plague research institute in Siberia who contracted pneumonia of an “unknown” cause. Local state TV said the woman died last week. Russian authorities said they found no evidence that her illness was caused by any of the pathogens she worked with. But the case has raised alarm in Russia after unconfirmed media reports suggested she might have died of pneumonic plague — a less common but severe form of plague that can spread from person to person. The woman worked at the Irkutsk Anti-Plague Research Institute of Siberia and the Far East in Irkutsk, southeastern Siberia. A state TV station in Irkutsk reported Monday that she died last week in a hospital in Shelekhov, a town just outside Irkutsk. The hospital has been placed under quarantine, Mayor Maxim Modin said Friday, no longer admitting or discharging patients, and its laboratory halted carrying out routine tests. The hospital's outpatient clinic kept operating as usual, he said. Anna Popova, head of Russia’s public health watchdog,