All About Legionnaires' Disease


Recently in England and Wales, there were approximately 280 Legionnaires’ disease cases with a mortality rate of 12%. In the more susceptible groups this rate is thought to be in excess of 40%. Most cases were in males over 40 years old. Some 47% of cases are regarded as community acquired, as opposed to hospital acquired (approx 5%), and travel associated (38% abroad, 10% UK), according to data from the National Surveillance Scheme for Legionnaires’ Disease.

In the UK, Legionnaires’ disease has been most commonly associated with hot and cold water systems in large buildings, such as hospitals and hotels, and infections are usually sporadic as opposed to outbreaks with large numbers of people affected. Historically outbreaks have been associated with wet evaporative condensers (cooling towers), but increased controls have reduced incidences.

Well publicised examples of Legionellosis this year include an outbreak on the Black Watch cruise liner which affected 7 elderly people; 80 prisoners were evacuated from a Kent jail as a precautionary measure; and in a Sunderland health club up to 115 people may have been affected with Legionella-like symptoms. Household plumbing systems have also been implicated in sporadic cases of Legionnaires’ disease. In one UK study legionellae were isolated from approximately 15 % of the homes of affected patients in comparison with around 5 % of homes in a control group.

For more informtion on outbreaks and Legionella incidents see the following LINK

What is Legionella?

Legionella is a particularly aggressive form of bacteria that when inhaled in contaminated water droplets rapidly multiplies and produces a severe and potentially fatal form of pneumonia. Legionnaires' Disease mainly affects adults, with men being more at risk than women. The greatest incidence of disease is in men over 40 years of age who also smoke. Persons who are immuno-compromised or suffering from respiratory disorders are also at higher risk.

There are 300-400 identified Legionnaires' Disease cases reported each year in the United Kingdom. There are many more cases that go undetected, estimated figures would suggest 7-8,000.