What is “Legionnaires disease” and what causes it?
Legionnaires’ disease Legionnaires’ disease is an infection of the lungs (pneumonia) caused by a strain of bacteria called Legionella pneumophila. Legionnaires’ disease infects people when they breathe 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. Most cases of Legionnaires’ disease affect people over 50 years of age or people whose immune systems are weakened by smoking or by other diseases. Cause Pneumonia is most often caused by an infection with bacteria. Other bacteria that may cause pneumonia include Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella pneumophila (the bacteria that caus
