What is legionella and how to test for it?

If you are a business owner, landlord or property manager that owns properties, knowing about legionella and its dangers can be essential to prevent illnesses within your tenants and employees. But what exactly is legionella, where does it come from and how can you test for it?

In this article, we are going to explain what legionella is and where it comes from, explore its dangers, inform you on how to test for it and give you some tips and tricks on what to do if you find it in your properties’ water systems.

What is legionella?

Legionella is a naturally occurring bacteria that can be present in bodies of freshwater, such as lakes, streams and ponds. While legionella bacteria typically exists in low concentrations in these natural environments, it can become a problem when it grows in artificial water systems like plumbing, cooling towers, and hot tubs. Under the right conditions – warm temperatures and stagnant water – Legionella can multiply and pose a risk to human health, causing illnesses such as Legionnaires’ Disease and Pontiac Fever.

What is Legionnaires’ Disease?

Legionnaires’ disease is a severe form of pneumonia usually caused by becoming infected with legionella bacteria. The symptoms include a bad cough, shortness of breath, a fever, muscle aches, and headaches. It can be fatal, particularly in older adults, smokers, and those with weakened immune systems. In fact, it can be fatal in around 20% of reported cases. 

Although legionella bacteria are prevalent in rivers, ponds and soil, the conditions are very rarely right for people to contract Legionnaires’ disease from these places. Instead, outbreaks of Legionnaires’ disease usually occur by inhaling small water droplets containing the bacteria in purpose-built systems where the water is kept at high enough temperatures for the bacteria to grow. These places include cooling towers, evaporative condensers, and spa pools. If these systems have a water temperature of between 20-45 °C, contain deposits such as rust or sludge that can support bacterial growth, or the water is stored or recirculated, the risk of legionella is increased.

Who is at a higher risk of catching Legionnaires’ Disease?

In 2020, there were 254 confirmed cases of Legionnaires’ disease in the UK. However, most people who are exposed to legionella won’t become ill. 

Certain groups of people are at a higher risk of catching Legionnaires’ disease, particularly those with weakened immune systems or underlying health conditions. The main risk factors include:

• Age: People aged 50 and older are more susceptible to Legionnaires’ disease.
• Smoking status: Current or former smokers have damaged lungs, which makes them more vulnerable to the disease.
• Chronic lung disease: Individuals with chronic lung conditions like chronic obstructive pulmonary disease (COPD) or emphysema are at increased risk.
• Weakened immune system: People with weakened immune systems, such as those with cancer, diabetes, or kidney failure, as well as individuals on immunosuppressant drugs, are more likely to get sick.
• Underlying health conditions: Those with heart disease, diabetes, or liver failure are more prone to infection.
• Hospitalisation: Patients in hospitals, especially those on mechanical ventilation, are at higher risk due to the potential for contamination in hospital water systems.
• Frequent travellers: People who stay in hotels or on cruise ships are at higher risk because of potential exposure to contaminated water systems in these settings.

What is Pontiac Fever?

Pontiac Fever is a less serious form of legionella-related illness than legionnaires’ disease, consisting of mild flu-like systems including a fever, headaches and fatigue. The illness usually resolves on its own within a few days without causing any lasting effects, and those who have been diagnosed with Pontiac Fever often don’t need treatment. Unlike Legionnaires’ disease, Pontiac Fever does not involve pneumonia and is generally not life-threatening, making it a much milder infection. 

Who is at risk of catching Pontiac Fever?

Because Pontiac Fever is generally mild and doesn’t have the same severe risk factors as Legionnaires’ disease, it affects a broader range of people. Pontiac Fever can affect anyone who is exposed to Legionella bacteria, but certain groups may be at a slightly higher risk due to increased likelihood of exposure or underlying factors. Those at a higher risk include:

• People frequently exposed to contaminated water systems: People who work in environments with water systems, such as cooling towers, hot tubs, or decorative fountains, may have a higher risk of exposure.
• People who live in outbreak areas: During outbreaks of Legionella in places like hotels, workplaces, or public buildings, people in those locations may be more likely to contract Pontiac Fever.

How often should I test for legionella?

How often you test for legionella depends on the types of water systems you have on your property. It is recommended that open systems like cooling towers and spa pools are tested at least once a quarter, whereas enclosed water systems don’t need to be tested as often as they are less prone to contamination.

If, however, you test for legionella and the results come back positive, your water systems should undergo testing every week until the bacteria is removed and the water is once again safe.

How to test for legionella

There are three different methods for testing your water systems for the presence of legionella bacteria:

1. Lab-based testing: Samples are taken from your water systems and sent to a UKAS-accredited lab to check for the presence of legionella bacteria. Results can take up to two weeks to be delivered.
2. PCR (Polymerase Chain Reaction) testing: Similarly to the lab-based tests, samples of water are take from your systems and sent to a lab. However, the results only take a few hours, as opposed to several days/ weeks. Because of the accuracy and speed of the results, legionella PCR tests are more expensive than the other methods.
3. Rapid swab testing: Rapid swab testing is the only DIY test for legionella. The testing kits can be purchased online and done by yourself, rather than sending a sample to a lab. A swab is used to collect a sample and is added to a reagent or buffer solution. Most rapid swab testing kits use lateral flow devices (similar to the Covid tests), where a few drops of the processed sample are added to a test strip which shows the result in a few minutes. However, despite being quick and convenient, they shouldn’t be used as an alternative – a lab test will still be required to assess the level of contamination.

How can I prevent legionella bacteria in my building?

If you’re worried about the presence of legionella bacteria in the water systems within your building, there are a few different simple measures you can take to prevent legionella exposure. These include:

• Removing debris regularly and adding measures to prevent debris from entering, such as lids for water tanks
• Increasing the temperature to  60°C so that legionella bacteria cannot grow
• Get rid of old redundant pipework
• Undergo a regular full flush of water systems
• Keeping on top of plumbing repairs

If you’d like help checking your systems and plumbing, get in touch with us today.