Legionnaires’ disease is a potentially fatal lung infection (pneumonia) that is caused by the bacteria legionella.
The condition is called Legionnaires’ disease because it was first identified after a mass outbreak at a hotel hosting a convention of a veteran organisation known as the American Legion.
Legionella
Legionella bacteria is commonly found (often in low numbers) in sources of water, such as rivers and lakes.
The bacteria sometimes find their way into artificial water supply systems, such as air conditioning systems, hot and cold water services, and cooling towers. Given the right conditions, legionella bacteria can rapidly spread, contaminating these water systems.
Legionnaires’ disease is not contagious
Legionnaires’ disease is contracted by breathing in small droplets of contaminated water. However, the condition is not contagious and cannot be spread directly from person to person.
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 legionella contamination can quickly spread.
There are strict regulations regarding the maintenance and control of water supply systems, such as either keeping the water cooled below 20C (68F), or heated above 60C (140F), in order to prevent an outbreak of Legionnaires’ disease.
How common is Legionnaires’ disease?
During 2006, there were 551 reported cases of Legionnaires’ disease in England and Wales. It is thought that 160 of these cases occurred while the affected person was travelling abroad.
The actual number of cases of Legionnaires’ disease may be much higher than the reported number of cases. This may be due to people with mild symptoms of the condition being misdiagnosed with more common forms of pneumonia and so these cases may not be reported to the health authorities.
Prognosis
In particularly vulnerable people, such as the elderly, or people with a pre-existing health condition, Legionnaire’s disease can be very serious.
An estimated 10% of people who contract Legionnaires’ disease will die from complications arising from infection. In 2006, there were 52 deaths from Legionnaires’ disease in England and Wales.
Prompt treatment using antibiotics is essential in treating Legionnaires’ disease and reducing the risk of death.
