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Legionnaires' Disease

Legionnaires' disease is an infection of the lungs (pneumonia) caused by a type of bacteria called Legionella pneumophila.

People develop Legionnaires' disease from breathing in the bacteria, which may be carried in airborne water droplets from contaminated water sources, such as air-conditioning cooling towers, plumbing systems, hot water tanks, and spas. These sources often have warm, stagnant water that allows bacteria to grow. People who work near natural bodies of water do not appear to be at risk.

Legionnaires' disease is not passed from one person to another. It usually occurs in single, isolated cases or in groups of people who are exposed to the same source of infection. Most cases of Legionnaires' disease affect people older than 50 or people whose immune systems are weakened by other diseases or by smoking.

By Healthwise Staff
Primary Medical Reviewer Kathleen Romito, MD - Family Medicine
Specialist Medical Reviewer Adam Husney, MD - Family Medicine
Current as of October 8, 2013

WebMD Medical Reference from Healthwise

Last Updated: October 08, 2013
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.