Pneumonic plague is a severe lung infection caused by the bacterium Yersinia pestis. Symptoms typically appear three to seven days after exposure and include fever, headache, weakness, rapidly developing pneumonia, shortness of breath, chest pain and coughing—often with blood. The pneumonia progresses over two to four days and can lead to respiratory failure and shock.
It is one of three plague forms. Pneumonic plague affects the lungs, bubonic plague targets lymph nodes, and septicemic plague infects the bloodstream.
The infection can develop as a primary illness from inhaling aerosolized bacteria or secondarily when bubonic or septicemic plague spreads to the lungs. Transmission occurs through breathing airborne droplets from an infected person or animal, or from handling contaminated animal tissue. Unlike bubonic plague, which spreads only through vectors such as fleas, pneumonic plague spreads directly between people.
Diagnosis involves testing blood, sputum or fluid from a lymph node. Treatment relies on antibiotics. Without early intervention, pneumonic plague is almost always fatal, with some patients dying within 36 hours.
Preventative measures include avoiding contact with infected individuals and animals and wearing correctly fitted surgical masks. Isolation is recommended for those infected to limit further spread.
Pneumonic plague is more serious than bubonic plague, though less common. Historical accounts suggest the pneumonic form was a primary driver of the Black Death in the 1300s, which killed approximately 25 million people.
Yersinia pestis is present among rodent populations across Africa, the Americas and Asia. Vaccines are under development but are not yet commercially available in most countries. In 2013, the total reported number of all types of plague cases globally was 783.
