WHO probes Russian lab researcher's pneumonic plague death

A 28-year-old lab researcher at a Russian anti-plague institute died of pneumonia of unknown origin, prompting the World Health Organization to contact Russian health authorities to verify the incident and assess potential international public health implications. Pneumonic plague, a rare and deadly lung infection caused by Yersinia pestis, is considered the most dangerous form of the disease and the only type that transmits directly from person to person via respiratory droplets. Symptoms include severe pneumonia, fever, and nausea, and without antibiotic treatment within 24 hours, it is nearly always fatal. The last U.S. death from pneumonic plague occurred in Arizona in July 2025, contracted from sick cats, and the disease persists globally, with most human cases in Africa since the 1990s. The WHO currently assesses the public health risk to the general population as low, though it will update its assessment as more information becomes available.