What is Legionella?
Legionella is a type of bacteria that lives in water and can cause potentially fatal disease in humans, such as Legionnaires’ disease. Legionella bacteria are widespread in natural water systems, e.g. rivers and ponds but the risk of exposure in these environments is very low.
Outbreaks of illness occur from exposure to legionella growing in purpose-built systems where water is maintained at a temperature high enough to encourage growth, e.g. domestic water storage systems, cooling towers and spa pools.
Legionnaires’ disease is a potentially fatal form of pneumonia and everyone is susceptible to infection. However, some people are at higher risk, including:
- People over 45 years of age
- Smokers and heavy drinkers
- People suffering from chronic respiratory or kidney disease
- Anyone with an impaired immune system
How does exposure occur?
People can catch Legionnaires’ disease by inhaling small droplets of water suspended in the air that contain the bacteria. Certain conditions increase the risk from legionella, including:
- Infrequently used water outlets such as taps or shower heads, especially in spare or rarely used rooms
- A water temperature between 20–45 °C, which is the optimum range for the growth of the bacteria
- The creation of breathable droplets of water, e.g. spray from taps or shower heads
- A source of nutrients available for the organism e.g. sludge or lime scale
Symptoms are similar to those of flu, i.e. high temperature, fever and chills, cough, muscle pains and headache. In a severe case, there may also be pneumonia, and occasionally diarrhoea and signs of mental confusion. Legionnaires’ disease is not known to spread from person to person.
What can you do?
You don’t need to do much to reduce the risk in your own home, as regularly used water outlets present little risk of infection.
However, if you go on holiday it is a good idea to run all the taps and shower heads in the house for two minutes on your return, being careful not to create a mist or spray.
If you have any water outlets that are rarely used it is good practice to run these for a couple of minutes every two weeks. Regular cleaning of shower heads is also advisable.