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About the Disease

Español: Sobre la enfermedad

Legionellosis (LEE-juh-nuh-low-sis) is a respiratory disease caused by Legionella bacteria. Sometimes the bacteria infect the lungs and cause pneumonia — if so, it is called Legionnaires' disease. The bacteria can also cause a less serious infection that seems more like a mild case of the flu. That form of legionellosis is commonly called Pontiac fever.

The following pages give information about Legionnaires’ disease and Pontiac fever, including how people get sick and treatment options.