Legionella is a type of bacteria found naturally in freshwater environments, such as lakes and streams. However, it can become a health concern when it grows and spreads in human-made water systems, including cooling towers, hot water tanks, large plumbing systems, and decorative fountains.

When people are exposed to water droplets or mist contaminated with Legionella bacteria, they can contract a severe form of pneumonia known as Legionnaires’ disease. This illness is particularly dangerous for older adults, smokers, and individuals with weakened immune systems. Symptoms often include cough, shortness of breath, fever, muscle aches, and headaches. If left untreated, Legionnaires’ disease can be fatal.

Legionella can also cause a milder illness known as Pontiac fever, which is similar to the flu but does not lead to pneumonia.
Outbreaks typically occur when water systems are not properly maintained, allowing the bacteria to grow and spread. Preventive measures include regular maintenance, cleaning, and disinfection of water systems, as well as monitoring water quality to reduce the risk of Legionella contamination.