epidemiology
Last reviewed 01/2018
Legionella is an airborne infection with the bacterium sometimes living in air-conditioning systems, whirlpool spas and domestic hot water systems in large buildings.
In the UK there are about 200 cases per year, of which one third have been contracted abroad. It accounts for 2-16% of pneumonias in the UK. Men are affected three times more frequently than women. It is uncommon in children.
Mortality is 10-15% however in the elderly mortality may reach 30%.
Three epidemiological patterns are recognised:
- in previously fit individuals living in an institution in which, for example, the shower or cooling system are contaminated
- in immunocompromised and elderly male smokers
- sporadic
Reference:
- Joseph, C. New outbreak of legionnaire's disease in the United Kingdom (2002). BMJ, 325, 348-9.