Legionnaires' Disease


Legionnaires’ disease is a respiratory disease caused by breathing in small water droplets contaminated with Legionella bacteria. The bacteria thrive in biofilms, which can protect it from disinfectants. However, chloramine, the disinfectant used by the FKAA, has the ability to penetrate these biofilms and has been shown to be significantly more effective against the bacteria, when compared to chlorine, which does not penetrate the biofilm.

Most identified outbreaks are in buildings with large water systems, such as hotels, long-term care facilities, and hospitals. In these types of buildings, the most likely sources for spreading water droplets contaminated with Legionella include:

  • Cooling towers, which are parts of large centralized air conditioning systems
  • Decorative fountains and water features
  • Hot tubs
  • Showers and faucets

Those most at risk for getting Legionnaires’ disease include:

  • Adults 50 years or older
  • Current or former smokers and people with a chronic lung disease, such as emphysema
  • People with a weakened immune system caused by diseases or medicines


The key to preventing legionellosis is making sure that the water systems in buildings are maintained in order to reduce the risk of growing and spreading Legionella.

Additional Information

For more information visit the Center for Disease Control and Prevention’s Legionella webpage.