Russian health authorities have placed roughly 189 contacts under medical observation after the death of a 28-year-old laboratory worker at the Irkutsk Anti-Plague Institute in Siberia, with the White House and the U.S. Centers for Disease Control now monitoring the case. Darya Shipilova, a lab technician at the facility in Shelekhov, died overnight on October 1-2 in intensive care, according to local media and officials.

Local reports say Shipilova broke a test tube containing Yersinia pestis - the bacterium that causes plague - on September 25, while other accounts suggest she may have been exposed during fieldwork in Buryatia near the Mongolian border. Buryatia's governor, Alexei Tsydenov, wrote on Telegram that she "died, maybe of the plague." Russia's health watchdog Rospotrebnadzor recorded her death as "pneumonia of unknown etiology" on October 4, saying no lab-linked microorganisms had been detected and describing the situation as stable.

As a precaution, about 189 people have been placed under three-week observation and hospitals in the region have closed to visitors; the Irkutsk Aluminum Plant ordered workers to wear masks. Governor Igor Kobzev said contacts remain asymptomatic and their tests have come back negative. A criminal investigation into possible safety violations has been opened, and Rospotrebnadzor chief Anna Popova was dispatched to Irkutsk.

The U.S. State Department told Al Jazeera it is "monitoring the situation closely with the CDC" and urged Russian authorities "to share accurate information quickly and openly." Axios reported the White House is "aware, monitoring the outbreak, and assessing options." So far there is no confirmed case of plague transmission beyond the single death - but with transparency questions swirling, health officials on both sides are treating the episode with unusual seriousness.