Pneumonic plague is a really serious lung infection, often described as the most virulent form of plague, caused by the bacterium Yersinia pestis. While bubonic plague affects the lymph nodes and septicaemic plague targets the blood, pneumonic plague can develop as a secondary infection when these strains spread to the lungs, or through direct human-to-human transmission via infectious respiratory droplets.
The World Health Organization has sought further details from Russia following the death of a worker at a Siberian plague research laboratory. While Russian officials continue investigating the exact cause of death, preliminary testing indicated that individuals who came into contact with the researcher tested negative for pneumonic plague. The incident has drawn international attention, with US President Donald Trump stating that Washington was looking “very strongly” at the case and the UK Health and Safety Authority noting that the risk to Britain’s population was “very low”.
Pneumonic Plague Spreads Through Infected Air Droplets
Plague is fundamentally an infectious disease driven by bacteria typically found in small mammals and their fleas. Humans generally contract the disease through the bite of an infected flea or by handling infected animals. However, pneumonic plague stands apart because it can spread directly between people when an infected person coughs infected droplets into the air, which are then inhaled by someone nearby.
Prof Piero Olliaro, Professor of Poverty-Related Infectious Diseases at the University of Oxford, explained that the underlying pathogen has not vanished from the globe. “Plague itself has not disappeared: the bacterium that causes it, Yersinia pestis, persists in animal reservoirs across many parts of the world,” he said, noting that approximately 200 rodent species can harbor the bacterium across the Americas, Eurasia, and Africa.
Global infection figures for all three forms of plague fluctuate annually, generally estimated between 1,000 and 3,000 cases worldwide. The majority of these involve bubonic plague and occur primarily in central Africa, though cases also surface in regions including Russia, India, China, and the United States.
Dr Zania Stamataki, Associate Professor of Viral Immunology at the University of Birmingham, emphasized the necessity of active laboratory research involving the live organism. “Plague is not a historical disease. It remains endemic in rodent populations across Africa, Asia and the Americas, and human cases occur every year, including outbreaks of the pneumonic form,” she said.
Rapid Antibiotic Treatment Prevents Fatal Pneumonic Plague
According to the World Health Organization, pneumonic plague features a very short incubation period that can span just 24 hours. Without rapid diagnosis and prompt medical intervention, experts warn that the infection is nearly always fatal. Common symptoms include shortness of breath, chest pain, and coughing up blood.
Despite its extreme virulence, the disease responds well to timely antibiotic administration. Dr Malick Gibani, Clinical Associate Professor in Bacterial Vaccinology at Imperial College London, noted that the condition remains a serious threat to public health. “Pneumonic plague is a very severe manifestation of plague disease,” he said, adding that while some textbooks suggest a high mortality rate if left untreated, early antibiotic therapy remains highly effective and high-risk contacts may receive prophylactic treatment or quarantine.
