Legionella bacteria are found in the environment. Human infection is most commonly caused by:
- Legionella pneumophila — found in man-made water systems such as cooling towers and spas
- Legionella longbeachae — found in potting mix and compost.
Infection with Legionella bacteria can cause:
- Legionnaires’ disease — a severe respiratory illness with pneumonia.
- Pontiac fever — a mild influenza-like illness without pneumonia.
People who work with potting mix and compost may be exposed to Legionella longbeachae bacteria. Infection can occur from breathing in dust and aerosols that contain the bacteria and from hand to mouth contact.