A 28-year-old laboratory technician at the Irkutsk Anti-Plague Institute in Russia died in a suspected case of pneumonic plague following a broken test tube.
Around 200 people who may have had contact with the technician have been placed under quarantine, while Russian authorities classified the case as pneumonia of unknown aetiology.
The US State Department and CDC are monitoring the reports, urging Russian officials to provide precise information regarding the unverified details.