After Legionella bacteria grows and multiplies in a building water system, water containing Legionella then has to spread in droplets small enough for people to breathe in. People can get Legionnaires’ disease or Pontiac fever when they breathe in small droplets of water in the air that contain the bacteria. Less commonly, people can get sick by intake of drinking water containing Legionella. This happens when water accidentally goes into the lungs while drinking. People at increased risk of aspiration include those with swallowing difficulties. In general, people do not spread Legionnaires’ disease and Pontiac fever to other people. However, this may be possible under rare circumstances.
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