Russian lab researcher dies of unknown pneumonia; plague risk low

A 28-year-old lab researcher at a Russian anti-plague institute in Siberia died of pneumonia of unknown origin, prompting international monitoring by the US and WHO, though officials say public risk appears low. Pneumonic plague, the deadliest form of Yersinia pestis, is a rare lung infection transmitted person-to-person via respiratory droplets, with symptoms like severe pneumonia, fever, and nausea, and is nearly always fatal without prompt antibiotic treatment. Plague persists globally, with most cases in Africa, and the last US pneumonic plague death occurred in Arizona in July 2025; WHO advises avoiding contact with the sick and using protective equipment for caregivers.