Legionellosis is the collective name given to the pneumonia-like illness caused by legionella bacteria. This includes the most serious legionnaires’ disease, as well as the similar but less serious conditions of Pontiac fever and Lochgoilhead fever. 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
The bacterium Legionella pneumophila and related bacteria are common in natural water sources such as rivers, lakes and reservoirs, but usually in low numbers. They may also be found in purpose-built water systems such as cooling towers, evaporative condensers and whirlpool spas.
If conditions are favourable, the bacteria may grow increasing the risks of legionnaires’ disease. Therefore, it is important to control the risks by introducing measures outlined in Legionnaires’ disease – The Control of Legionella bacteria in water systems (L8).
Identify and assess sources of risk
Manage the risk
Prevent or control the risk
If you are an employer, or someone in control of premises, including landlords, you must understand the health risks associated with legionella and why you must carry out a legionella risk assessment.
Duties under the Health and Safety at Work Act 1974 extend to risks from legionella bacteria, which may arise from work activities. The Management of Health and Safety at Work Regulations provide a broad framework for controlling health and safety at work and more specifically the Control of Substances Hazardous to Health Regulations 2002 (COSHH) provide a framework of duties designed to assess, prevent or control the risk from bacteria like Legionella and take suitable precautions.
Legionnaires’ disease: The control of Legionella bacteria in water systems (L8) contains practical guidance on how to manage and control the risks in your system.
As an employer, or a person in control of the premises, you are responsible for health and safety and need to take the right precautions to reduce the risks of exposure to legionella. You must understand how to:
identify and assess sources of risk
manage any risks
prevent or control any risks
keep the correct records
carry out any other duties you may have
Legionella bacteria are widespread in natural water systems, e.g. 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 water is maintained at a temperature high enough to encourage growth, e.g. cooling towers, evaporative condensers, spa pools, and hot water systems used in all sorts of premises (work and domestic).
It is now known that Legionella is fairly common in natural water systems, but that was not always the case. The bacteria wasn’t identified until 1976 when more than 200 people who attended an “American Legion” convention at the Bellevue-Stratford Hotel in the American city of Philadelphia began to report being seriously ill shortly after returning home.
34 would eventually die before the bacteria was identified and the type of pneumonia the victims suffered from was named “legionnaires’ disease” in their honour. It was eventually theorized that the bacteria had thrived in the water of the hotel’s air conditioning system and that the affected people had breathed in contaminated water droplets that had fallen from air conditioning units where water was stored on the roof onto the sidewalk around the hotel.
People can catch legionnaires’ disease by inhaling small droplets of water, suspended in the air, containing the bacteria. Certain conditions increase the risk from legionella, including:
water temperature between 20–45 °C, which is suitable for growth
creating and spreading breathable droplets of water, e.g. aerosol created by a cooling tower, or water outlets
stored and/or re-circulated water
a source of nutrients for the organism e.g. presence of sludge, scale or fouling
While most cases of legionnaires’ disease are the result of infections caught in the UK, a number of cases occur abroad.
The 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, as well as signs of mental confusion. Legionnaires’ disease is not known to spread from person to person.
In most cases, symptoms develop in 2 to 10 days following exposure to the legionella bacteria. As mentioned, common symptoms include headache, muscle pain and fever. For some people, that is as far as the disease will go. Others, however, will experience a dangerous escalation of symptoms beginning 2 or 3 days after the original onset. Those new, more severe symptoms may include:
Cough (often with mucus and sometimes blood).
Respiratory distress in the form of shortness of breath or wheezing.
An escalating fever perhaps reaching as high as 104F (40C), sometimes higher.
A heavy sensation in the chest or chest pain.
Diarrhoea, nausea and/or vomiting.
Confusion, loss of mental sharpness.
Infections in other parts of the body besides the lungs.
A less severe form of Legionnaires’ Disease commonly known as “Pontiac Fever” will typically produce similar symptoms but not to any extreme degree. For instance, there is no coughing up blood and no lung infection. Pontiac Fever typically resolves in 2 to 5 days.
If you are exhibiting any of the above symptoms or have any reason to suspect exposure to legionella bacteria, you should see your doctor immediately for a legionella test. Early detection is critical if you are to avoid it developing into a serious respiratory condition. Keep in mind too that the risk of exposure is more acute for older individuals and smokers.