What is Legionnaires' Disease?

Legionellosis is a collective term for diseases caused by legionella bacteria including the most serious Legionnaires’ disease, as well as the similar but less serious conditions of Pontiac fever and Lochgoilhead fever. Legionnaires’ disease is a potentially fatal form of pneumonia and everyone is susceptible to infection. The risk increases with age but some people are at higher risk including:

• People over 45 years of age
• Smokers and heavy drinkers
• People suffering from chronic respiratory or kidney disease
• People suffering from Diabetes, lung and heart disease
• Anyone with an impaired immune system

The bacterium Legionella pneumophila and related bacteria are common in natural water sources such as rivers, lakes and reservoirs, but usually in low numbers. They are also found in purpose-built water systems such as cooling towers, evaporative condensers, hot and cold water systems and spa pools where human contact is more likely and where increased risk is found.

If conditions are favourable, the bacteria may grow increasing the risks of Legionnaires’ disease and it is therefore important to control the risks by introducing appropriate measures outlined by the HSE guidance documents HSG 274 and ACoP L8.

The main route of infection is through inhalation, by breathing in airborne water droplets that contain Legionella bacteria. The majority of cases or outbreaks of the disease have been via domestic water systems, evaporative cooling towers, poorly maintained artificial water systems and spa pools.

It is vital that ALL water systems implement the required control methods specific to the type of system and its design and continuously assess the risk where any changes may occur.