What is Legionnaires Disease | Causes of Legionnaires Disease

 
What is Legionnaires' disease?
The name "Legionnaires' disease" was coined in 1976 after a respiratory disease affected many delegates attending a convention in Philadelphia held by the American Legion of Pennsylvania. Eventually, the bacteria that was responsible for the disease was isolated and named as Legionella pneumophila.
Two distinct illnesses, Legionnaires' disease and Pontiac fever, have been associated with the Legionella species. Legionnaires' disease is a severe pneumonia. Pontiac fever is a mild, non-pneumonia influenza-like illness. It is not clear why the same causal agent can produce two distinct illnesses.
In this document, we refer only to Legionnaires' disease. Pontiac fever is apparently uncommon; only a few outbreaks have been reported in the world. One of them, a large one, was in Canada.

What is the cause of Legionnaires' disease?
The bacterium responsible for Legionnaires' disease belongs to the genus Legionella. There are approximately 35 Legionella species known to produce the disease. Legionella species are commonly found in any aquatic environment. They can survive for several months in a wet environment and multiply in the presence of algae and organic matter.