What is Legionella?

Legionella bacteria are motile bacteria that can cause Legionellosis. ‘Legionellosis’ is a term that encompasses a collection of diseases, with Legionella Pneumophila sero-group 1 mainly associated with legionellosis. The most common of these is known as ‘Legionnaires’ Disease’, a form of pneumonia, it is also the most fatal.

The spread of legionella bacteria to humans is mainly through air borne water droplets dispersed by infected air and water systems. Legionella flourishes in air and water systems that operate at optimal temperatures of 20-45 0C . The risk of infection is high when the bacteria are present in these conditions as multiplication and growth of the bacteria will be at its greatest rate.

Legionella is just one form of harmful bacteria that we treat in contaminated water and air systems. Other bacteria such as Pseudomonas can thrive in such conditions and, like legionella, will feed off any nutrients available including rust and bio fouling of a system.

Susceptibility to contracting a disease from these harmful bacteria after exposure is shown to be highly dependent on the type of system in use. There are several high-risk systems that are recognised dangers to the environment due to the production of water vapor droplets to the surrounding environment. Infection can also be dependent on the person in the affected area. Danger of infection can increase with age, smokers and heavy drinkers also at higher risk.  High-risk systems are :

  • Hot Tubs
  • Air Conditioning Units
  • Shower Heads

Although the presence of legionella bacteria has been detected in most natural water systems, the levels are low and harmless as the conditions for growth are unfavorable. The threat of Legionnaires’ disease spreading from natural water systems is low. However, poorly managed man made water systems that operate at high temperatures pose a greater threat as conditions can favour the growth of the harmful bacteria.