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Illustration of the major features of the lungs, including the bronchi, the bronchioles and the alveoli
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  • National Institutes of Health

Also called: Legionellosis

Legionnaires' disease is a type of pneumonia caused by bacteria. You usually get it by breathing in mist from water that contains the bacteria. The mist may come from hot tubs, showers or air-conditioning units for large buildings. The bacteria don't spread from person to person.

Symptoms of Legionnaires' disease include fever, chills, a cough and sometimes muscle aches and headaches. Other types of pneumonia have similar symptoms. You will probably need a chest x-ray to diagnose the pneumonia. Lab tests can detect the specific bacteria that cause Legionnaires' disease.

The bacteria are more likely to make you sick if you

  • Are older than 65
  • Smoke
  • Have a lung disease
  • Have a weak immune system

Legionnaires' disease is serious and can be life-threatening. However, most people recover with antibiotic treatment.

Centers for Disease Control and Prevention

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