Legionnaires' disease is a type of pneumonia. It is caused by bacteria called Legionella pneumophila. The bacteria got its name in 1976, when a group of people attending an American Legion convention became infected. Although it was present before 1976, Legionnaires' disease is being diagnosed more often now as doctors look for Legionella bacteria in people who have pneumonia. You can get Legionnaire's disease at any time of the year, but more cases are usually found in the summer and early fall. While Legionnaires' disease can be very serious, most cases can be treated successfully.
The Legionella pneumophila bacteria can also cause a less severe, flu-like condition known as Pontiac fever.
Recommended Related to Lung Disease/Respiratory Problems
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People usually get Legionnaires' disease or Pontiac fever when they breathe in a mist or vapor (small droplets of water in the air) that contains the bacteria. One example might be from breathing in the steam from a whirlpool spa that has not been properly cleaned and disinfected. Other sources include fountains and water sources in hotels, cruise ships, nursing homes, and hospitals.
These diseases aren't contagious. The bacteria are not spread from one person to another person. You can get the diseases again if you are exposed to the bacteria again.
Legionnaires' disease typically affects people older than 45, especially if they smoke or have a long-term lung disease such as asthma.1 People with a weak immune system are also more likely to get the condition. Despite its being named after infecting a large group of people, Legionnaires' disease usually occurs in single cases, not in large groups at one time (an outbreak).
Pontiac fever usually occurs in otherwise healthy people.
What are the symptoms?
The most common symptoms of Legionnaires' disease include: