Pontiac fever is a mild flu-like sickness caused by Legionella bacteria exposure. It produces a moderate upper respiratory infection with symptoms similar to acute influenza. Pontiac fever cures spontaneously and is often misdiagnosed. The same bacterium may cause Pontiac fever and the more serious Legionnaires’ disease; however, Pontiac fever does not entail pneumonia.
Infection arises after inhaling aerosolized contaminated water. Legionella may infest microdroplets that are undetectable to the human eye. These bacteria, which are naturally found in the environment, develop very swiftly in water with a temperature range of 25 to 45 °C. As a result, artificial water systems are the primary source of pollution.