How doesLegionnaires disease spread?

Legionnaires disease is caused by Legionella bacteria infecting your lungs. It's usually caught by breathing in small droplets of contaminated water. The infection isn't contagious and can't be spread directly from person to person.

Legionella bacteria isusually found (often in harmlessly low numbers) in sources of water, such as ponds, rivers and lakes. However, the bacteriacan rapidly multiply ifthey find their way into artificial water supply systems, such as air conditioning systems.

Large buildings, such as hotels, hospitals, museums and office blocks, are more vulnerable to Legionella contamination because they have larger, more complex water supply systems in which the bacteria can quickly spread.

The two things that Legionella bacteria need to grow and reproduce are:

  • a water temperature of 20-45C (68-113F)
  • impurities in the water that the bacteria can use for food such as rust, algae and limescale

Although rare, Legionnaires' disease has also come from contaminated showers, sprinkler systemsand spas.

Legionnaires' disease is rare in the UK. In 2013, 284 people were reported to have the infection in England and Wales. Of these cases, 88 people (31%) were exposed to the infection while travelling abroad mainly to Mediterranean countries, but also tropical countries such as India. However, given the millions of trips made abroad each year, 88 cases is a very small number.

Cases of Legionnaires' disease arising in England and Wales usually peak between July and September.

Content supplied by the NHS Website

Medically Reviewed by a doctor on 21 Dec 2018