Legionnaires’ disease is a type of pneumonia. It was named after an outbreak of severe pneumonia that affected a meeting of the American Legion in 1976. It is an uncommon but serious disease. It is actually one of a group of similar diseases collectively known as legionellosis. The other forms, eg Pontiac Fever and Lochgoilhead Fever, have similar symptoms but are not as serious as Legionnaires’ disease.
Legionella bacteria are widespread in nature, mainly living in natural water systems, eg rivers and ponds. However, the conditions are rarely right for people to catch the disease from these sources.
Outbreaks of the illness occur from exposure to legionella growing in purpose-built systems where the water is maintained at a temperature high enough to encourage growth, eg cooling towers, evaporative condensers, spa pools, and hot water systems used in all sorts of premises (work and domestic).
Most community outbreaks in the UK have been linked to installations such as cooling towers, which can spread droplets of water over a wide area. These are found as part of air-conditioning and industrial cooling systems.
The agent that causes Legionnaires’ disease is a bacterium called Legionella pneumophila. People catch Legionnaires’ disease by inhaling small droplets of water suspended in the air, which contain the bacteria.
Certain conditions increase the risk from legionella:
- a suitable temperature for growth, 20 to 45oC
- a source of nutrients for the organism, eg sludge, scale, rust, algae, and other organic matter
- a way of creating and spreading breathable droplets, eg the aerosol created by a cooling tower or spa pool.
However, remember that most people exposed to legionella do not become ill, and Legionnaires’ disease does not spread from person to person.
The symptoms of Legionnaires’ disease are similar to those of flu:
- high temperature, fever and chills
- muscle pains
Most patients who are admitted to hospital develop high fever often greater than 39.5°C (103°F). In a bad case there may also be pneumonia, and occasionally diarrhoea and signs of mental confusion.
To prevent exposure to the legionella bacteria, a selected ’responsible person’ must comply with legislation that requires someone to manage, maintain and treat water systems in your premises properly. This will include, but not be limited to, appropriate water treatment and cleaning regimes.
Remember, legionella can grow in any workplace if the conditions are right – you do not have to work with microbiological agents, eg in a laboratory, for exposure to occur. If you are responsible for any of the water systems described in HSE’s Approved Code of Practice (ACoP) and Guidance “Legionnaires’ disease: The control of legionella bacteria in water systems” (L8) you will need to assess the risk of employees and others in the workplace contracting Legionnaires’ disease.
In a Legionella control context the term “Responsible Person” is identified in the HSE’s Approved Code of Practice & Guidance document L8 as someone with day-to-day responsibility for controlling any identified risk from Legionella bacteria.
The appointed “Responsible Person” should be a manager, director, or have similar status and sufficient authority, competence and knowledge of the installation to ensure that all operational procedures are carried out in a timely and effective manner. They should also have a clear understanding of their duties and the overall health and safety management structure and policy in the organisation.