Legionella, 10 important things you should know

26 February 2016


If you are a landlord, employer or someone in control of premises, it is important that you understand and mitigate the risks associated with Legionnaire's Disease.

You are responsible for the health and safety of your tenants and employees and should take the necessary precautions to reduce the chances of exposure to the disease.

Here are 10 important things you should know:

  1. A Brief History
    Historically, Legionnaire's Disease is actually a fairly recent discovery. It first acquired its name in 1976 after an outbreak in Philadelphia. The main victims of the outbreak were members of the American Legion, hence the name, Legionella. It was later found that 221 people were affected by the disease, which had been transmitted to them through an air conditioning unit.

  2. Where can it be found?
    The bacteria itself can be naturally found in the environment, existing mainly in water and moist soil. However, it can usually be found lurking in warm and stagnant water, where it thrives and becomes more dangerous.

  3. Legionnaire's disease
    Legionnaires’ is the disease that is caused by the bacteria; and everyone can be susceptible to it. It is fatal in 10-15% of cases, particularly if it isn’t diagnosed in the early stage of the illness. There are around 300 cases of the disease in the UK every year.

  4. What is the effect?
    Most people with the disease will develop pneumonia as the bacteria grows and thrives in the lungs. The symptoms are similar to many other forms of pneumonia, making it difficult to diagnose. Generally, symptoms begin 2 to 10 days after exposure and signs include: coughing, shortness of breath, fever and aches.

  5. How is it contracted?
    People can contract the disease when they breathe in water droplets (mist or vapour) that have been contaminated with the bacteria. Some people are at higher risk, such as people over 50 years old, smokers and those suffering with respiratory diseases.

  6. Transmission
    Fortunately, the disease cannot be transmitted between people.  Though the disease can occur at any time of year, data gathered in 2014 by the UK government showed that cases peak in the summer months, generally July-October, with over 70% of cases occurring in this timeframe.

  7. Outbreaks
    Outbreaks, though rare, can affect a larger amount of people. They are usually associated with large buildings with complex water systems, such as hotels and public buildings. The outbreaks are particularly dangerous because the symptoms are often delayed and commonly misdiagnosed, which can lead to a larger number of fatalities. Recent stories in New York, where 12 people died and the further nine deaths in Flint, Michigan, have exemplified this.

  8. Treatment
    If diagnosed early and correctly, the disease can be treated immediately with antibiotics and most cases are successfully treated this way. Healthy people normally make a full recovery after contracting Legionnaire’s disease, but hospitalisation is normally required.  However, it's worth noting that a significant number continue to suffer years later from Legionnaire's Disease Syndrome.

  9. Why should businesses be careful?
    Any water system has the potential to harbour the bacteria. Cooling towers and showers are most commonly involved with dangerous outbreaks, because of the high volumes of breathable droplets they produce. Susceptible systems include:
    • Cooling towers
    • Evaporative condensers
    • Dry/wet cooling systems
    • Hot and cold water systems
    • Spa pools

    Some outbreaks have even been attributed to public fountains, air conditioning systems and even the misters found in supermarkets.

  10. Prevention
    The key way to prevent infection is to simply keep the bacteria out of water. Businesses with systems that could pose a threat of legionella normally employ contractors to carry out water treatment to keep their employees and customers safe.

    However, the businesses themselves will be held responsible for any outbreak and must ensure that adequate management and training of staff is consistent. More information on responsibilities is available through the HSE.

    Prevention can be achieved in several ways:
    • Keeping water systems clean
    • Keeping temperatures below 18°, or above 50°
    • Chemical treatment
    • Reducing the escape of water droplets

For more information

DTL has published a FREE in-depth whitepaper, Controlling Legionella: Training and compliance for air conditioning and water systems maintenance – it looks at the causes of the disease, how artificial water systems allow bacteria to thrive, strategies to prevent it occurring in air conditioning and water systems, and the business benefits of legionella training from Develop Training (DTL).

Click here to download your FREE legionella whitepaper

Training courses for Legionella prevention

We can offer courses covering the following areas:

  • Hot and Cold Water Systems
  • Cooling Towers
  • Air Conditioning Equipment
  • Risk Assessments
  • Roles of the Responsible Person

For more information on our courses, please call one of our advisors on 0800 876 6708 or follow this link.