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Has Legionnaires’ disease gone away?

Collaborative Post

When it comes to waterborne diseases, people tend to think that they’re a thing of the past. After all, don’t we live in a modern world, where everything is clean and you don’t need to buy bottled water? Well, not quite. As we’ll see, one of the most dangerous waterborne illnesses – Legionnaires’ disease – is actually on the rise. Here’s what’s going on, and what you should be doing about it.

A brief history

First, what exactly is Legionnaires’ disease, and when did it start becoming an issue? Legionnaires’ disease is a form of atypical pneumonia, caused by the bacteria, Legionella pneumophila.

This bacteria tends to thrive in stagnant water sources such as water storage tanks, at specific temperatures. It spreads to humans through tiny drops of water called aerosols, which can enter into the air through any high-pressure water source, whether a tap, shower, or air conditioning unit.

The first known outbreak was at an American Legion convention in Philadelphia, in 1976. Within a few weeks of the convention, 29 people had died from the disease, with the total number of cases reaching 211. While this was likely not the first outbreak (others have been retrospectively diagnosed) it is to this day one of the most tragic, and the outbreak that led to the identification and naming of the disease.

Rising number of outbreaks

While there have been a number of regulations and mitigation strategies in place for years now to stop outbreaks of Legionnaires’, it appears that outbreaks have been sharply rising in recent years. In Europe in 2021 a massive 10,700 cases were reported, with 704 known deaths, although the actual number could be higher. Similar trends have been observed in America, pointing to a potentially highly serious health issue.

Mitigation strategies

We now know the exact conditions in which Legionella bacteria thrive. While the bacteria are present in most water sources, they start to proliferate in stagnant water sources between 20-45°C.

As a result, most mitigation strategies centre around ensuring that these conditions do not occur – basically, that any stagnant water sources, whether in a pipe or in a water storage tank, are kept at a higher or lower temperature than 20-45°C.

To ensure that this is the case businesses typically use water hygiene specialists to conduct Legionella risk assessments. These will typically consist of analysing the entire water supply system in a building, identifying potentially dangerous areas and testing water sources. Based on the findings, a number of recommendations will likely be made, some urgent some less so, in order to ensure the ongoing safety of the overall water system.

While Legionnaires’ disease does seem to be on the rise, this is absolutely unnecessary. There is a lot that businesses and governments can do to stop the spread of this disease, it simply takes a little time and effort. By using a water hygiene specialist and having a Legionella risk assessment carried out, you can see which areas your business is lacking in, and take action based on the findings of that assessment.

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