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Planning and Economic Development

Legionellosis (Legionnaires' Disease and Pontiac fever)

Legionnaires' disease Fact Sheet -printable page

Michigan is experiencing an increase in legionellosis cases. Legionnaires’ disease is a serious type of pneumonia (lung infection) caused by Legionella bacteria. Legionella can also cause a milder illness called Pontiac fever. People can get sick when they breathe in a mist or accidentally swallow water into the lungs containing Legionella. Legionellosis is most common in the summer and early fall when warming, stagnant waters are ideal for bacterial growth in water systems.

For more information on Legionnaires’ disease risk and prevention: