Legionnaires’ disease is an infection caused by breathing in small droplets of water contaminated by the Legionella bacteria. It is a severe form of pneumonia that can be fatal, and while relatively rare, there are around 350 confirmed cases identified in the UK each year.
Legionella is a type of bacteria that can grow in water. Water contaminated with the bacteria spreads Legionnaires’ disease, and many of the water systems in larger buildings like offices, hotels and hospitals will have the potential to grow and spread the bacteria if not controlled.
You can catch Legionnaires' disease if you breathe in tiny droplets of water from a contaminated water source that contains the Legionella bacteria. It is this bacteria that causes the infection within your respiratory system. You won't usually get it from drinking contaminated water, but instead when the droplets are inhaled and the bacteria enters your lungs.
You are most likely to get Legionnaires’ disease from:
High-risk systems can include air conditioning systems, water towers and other water storage. Any systems that create a fine spray of water can spread the disease to humans.
Legionnaires’ disease is a serious and potentially fatal lung infection, so it is important to be able to spot the symptoms early and take action. Unfortunately, because the symptoms are very similar to flu, treatment may be delayed. The elderly and the young are especially at risk due to having weaker immune systems to fight the illness.
Legionnaires’ disease is a serious illness and deaths may occur in approximately 10-15% of otherwise healthy individuals. The number of deaths reported may be higher (up to 40%) in some groups of patients, such as those who have weakened immune systems.
These symptoms aren't likely to start straight after you are exposed to a contaminated water source, as the disease can take days, and even weeks to develop, and gets progressively worse over a few days.
Due to the similarity to flu systems, it is not easy to diagnose Legionnaires disease. If you suspect Legionnaires disease you should contact your doctor, and let them know if you have been at any high-risk places in the last 10 days, like a spa or hotel. The diagnosis may be made with a blood or urine test, and you might need to go to the hospital for further tests and treatment.
Once the symptoms have been spotted and Legionnaires' disease has been diagnosed, it's important to establish where it was caught, as others will be at risk.
You can raise awareness with the Legionella Toolbox Talk.
If you suspect you have developed the illness through work you must report it to your employer. There is a then legal requirement for employers to report cases of Legionnaires' disease that may be acquired at their premises to the HSE.
Employers are required to carry out risk assessments for activities that may create risks to their workforce, and to reduce the risks as far as is reasonably practicable.
Duties under the Health and Safety at Work etc Act 1974 extend to risks from Legionella bacteria, which may arise from work activities, and the Control of Substances Hazardous to Health (COSHH) Regulations also cover bacteria.
There may be a risk of exposure to Legionella in any workplace, due to the presence of water systems, and an increased risk where water is stored within a water system. The Legionella risk within water systems must, therefore, be managed and controlled.
A risk assessment of the water system can be carried out to identify and assess sources of risk, and to put in place the necessary precautions to address any hazards and prevent or control the risks present.
Download our Legionella risk assessment template for help conducting a comprehensive risk assessment of your water system.