Legionella is a common bacterium found in natural environments including ponds, rivers, and lakes. The bacteria can also be supplied in small counts within mains water supply. Where there is water and the conditions of creating water droplets (aerosol), people using or within the area of these services may be at risk.
Legionnaires Disease is a form of pneumonia, which can be fatal. The most at risk are the very old and the very young, the ill and smokers to name a few. Legionella bacteria can also cause other, less harmful illness such as Pontiac fever and Lochgoilhead fever, which can affect all people.
The main route of infection is through inhalation, by inhaling airborne water droplets that contain Legionella. It cannot be spread from person to person. The majority of cases or outbreaks of the disease have been via domestic water services, evaporative cooling towers, and spa pools.