Legionella is a type of bacteria which causes Legionnaires’ disease. Legionella bacteria are found in natural watercourses, such as rivers and ponds. They may also contaminate and grow in other water systems such as hot water tanks, cooling towers, hot and cold water services, and decorative fountains. The bacteria can survive at low temperatures, however they thrive at temperatures between 20°C - 45°C.
Legionnaires’ disease is a potentially fatal form of pneumonia. It can affect everyone, however some individuals are at a higher risk of infection due to their age, current illnesses and lifestyle choices such as smoking.
An individual is affected by the disease through breathing in small water droplets which are contaminated with Legionella. Usually the water droplets need to be in a fine mist or spray. Once the bacteria are in the lungs, they multiply and can cause either pneumonia or a less serious flu-like illness, known as Pontiac fever. The disease cannot be passed on from person to person, and the majority of cases are reported as isolated cases; however outbreaks can occur.
Symptoms of Legionnaires’ disease can begin from 2 to 19 days after exposure to the initial infection; however the most common incubation period between being infected and the onset of symptoms is 6 to 7 days. Symptoms usually start with flu-like symptoms which typically last 1 to 2 days, these include:
- Confusion; and/or
Once the bacteria begin to infect your lungs, symptoms of pneumonia may also be experienced such as:
- Nausea and/or vomiting;
- Shortness of breath;
- Chest pain; and/or
- A persistent cough.
In order to comply with their legal duties, employers and those with responsibilities for the control of premises must carry out an assessment of the risks and a written scheme for controlling the risk from exposure to Legionella bacteria.
The assessment should include a description of:
- The hot and cold water system (an up to date plan or schematic diagram is sufficient);
- Who is responsible for carrying out the assessment and managing its implementation;
- The safe and correct operation of the system;
- What control methods and other precautions which will be used; and
- The checks that will be carried out on the control methods and how often these checks will be carried out, to ensure that they remain effective.
Water services should operate at temperatures that prevent multiplication of Legionella, this means that hot water storage should be at 60°C or hotter, hot water should be distributed so that a temperature of at least 50°C is achieved at the taps within one minute of running and cold water storage and distribution should be at 20°C or below.
Further information on Legionnaires’ disease can be found on the Health and Safety Executive’s website at www.hse.gov.uk and the Health Protection Agency’s website at www.hpa.org.uk