How can we prevent building-associated Legionella outbreaks?

Managing risks to the health of people who occupy your building is one of the most important aspects of your duties as a building manager. Taking a truly proactively preventive approach is crucial to minimising the risk of Legionella infection in the water system of your building. Here are a few ways in which you can save some time and money, prevent litigation, and maybe save lives.


Be able to separate the myths from the facts

There are a number of commonly held myths when it comes to Legionella.

Commonly held myth: first of all look at the cooling tower: Some still think air conditioning and cooling towers are mainly responsible for many of the cases of Legionnaires’ disease, while domestic plumbing systems of drinking water are a notable source too. These systems have been frequently linked to transmissions of Legionnaires’ disease in big buildings. Current data indicates that cooling towers, while might still be a potential source for Legionnaires’ disease, may be overemphasised as a means of Legionella bacteria transmission.

Commonly held myth: Legionella is everywhere: Legionella is indeed not everywhere. Some say that there is no point in actually testing for Legionella since we will always find it. There are several studies that dispute this information. As a matter of fact, Legionella colonises the water in twenty to seventy per cent of large buildings. Thus, wouldn’t you want to test and know if your building is one of the ones where Legionella is not found?

Commonly held myth: maintenance is the essential to prevention: A commonly held misconception is that quality engineering practices as well as preventive maintenance of the water system will prevent Legionella colonisation. But hospitals and commercial premises that followed preventive maintenance that included flushing hot water storage tanks on a weekly basis were just as likely to be contaminated with Legionella bacteria as those that did not.

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Commonly held myth: water stagnation can cause Legionella bacteria to multiply: Stagnation is believed to predispose water systems to colonisation by Legionella bacteria. A recent study, utilising a model plumbing system to determine the impact of flow regimes on the presence of Legionella bacteria within microbial biofilms, failed to demonstrate that stagnation stimulated growth of Legionella. Additionally, in another small study, removal of dead leg pipes did not actually decrease Legionella bacteria colonisation.


Be prepared

An unexpected inspection can severely interrupt your activities for the day. Or even worse, a positive Legionella test result, or many positive results, can arrive on your desk at any time. What we all dread most is the notification that a person in our building or community has contracted Legionnaires’ disease, or what is even worse, learning it was fatal. A knock on your door with legal action would soon follow such an event. Keeping an up-to-date risk management plan that tackles all of those scenarios can rapidly resolve problems before they become problems.


Create an interdisciplinary response team

Responding to Legionella outbreaks and other infectious waterborne pathogens found in water systems requires a team collaboration and effort. This team needs to include someone in your organisation who has gone through a thorough Legionella awareness training program and with sufficient knowledge of safety and health matters, it also needs to include your water treatment firm representative, a lab with Legionella expertise, as well as a Legionella risk management expert. This team can provide a proactive approach for prevention and develop an emergency plan to follow if necessary.

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Understand what are the sources of Legionella

Legionella may be found in the potable water systems in your building. This includes drinking water, water used for washing, bathing, cooking and water that flows from plumbing fixtures, boilers, cooling towers and other HVAC related equipment. In case water contaminated with Legionella is ingested, the bacteria may cause serious illness. Legionella can be transmitted through respiratory devices too. People “at risk” for Legionnaires’ disease are the elderly, immune system suppressed individuals and smokers.


Pick the ideal disinfection method

Selecting a disinfection method that works for you requires analysis based on efficacy, installation, cost as well as maintenance. Before choosing the ideal approach, go ahead and organise a task force, which should consist of administration, infection control practitioners, risk management and engineers. No technique will be successful without a conscientious monitoring system and committed personnel.


Verifying through tests

Testing the water system is really the only way to confirm the presence of Legionella bacteria. Studies tell us that there are no surrogate markers—temperature, disinfectant residual or chlorine—that will predict the presence of Legionella. For instance, total bacterial counts are not predictive of the presence of Legionella. Bottom line is: no matter what we do, if we do not test, we won’t be able to know. That is why leading specialists in the detection of Legionella strongly recommend culturing water to evaluate risk and verify the efficiency of disinfection.


Do not panic if your water system tests positive

If Legionella is actually present in your water system, the probability that illness will end up occurring mainly depends on who is in the building. Premises at high risk for Legionella include hospitals, nursing homes and other healthcare facilities. Also, an increasing number of cases are being reported from long-term care facilities.

In case the water in a high-risk building is colonised with Legionella bacteria, we need to treat the building to control Legionella and prevent an outbreak. Low-risk buildings, like commercial buildings or offices, will probably not require aggressive measures when Legionella is found.

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