Legionnaires' disease is a lung infection. It is a form of pneumonia. It got its name after it struck at the American Legionnaires Convention in 1976.

This disease is caused by the bacterium Legionella pneumophilia in most cases. The bacteria are most often found in sources of standing water. It may be found in cooling towers, HVAC systems, and air conditioners.

Legionnaires' disease can be contracted by breathing water vapor from a standing water source that contains Legionella bacteria.

The Lungs
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The infection does not move from one person to another.