There has been a worrying and significant rise in the number of confirmed cases of Legionnaires' disease over the past two years.
Overall, the annual number of laboratory-confirmed Legionellosis cases in England & Wales was lower in 2016 (359) than in 2015 (390). But the number of Legionnaires' disease cases rose to 448 in 2017. In 2018, in the eight months up until the end of August, the number of reported/notified cases of Legionnaire’s disease was already 447.
But what exactly is Legionella and how does it lead to Legionnaires' disease? The Health & Safety Executive advise, “Legionnaires' disease is a potentially fatal form of pneumonia caused by the inhalation of small droplets of contaminated water containing Legionella. All man-made hot and cold water systems are likely to provide an environment where Legionella can grow.”
The conditions which make the bacteria more favourable include a suitable growth temperature range of 20-45°C(warm room temperature and above); when water droplets (aerosols) are produced and dispersed; water stored and/or recirculated and if there is some 'food' present on which the organism feeds and is allowed to grow such as rust, sludge or scale. These conditions allow the bacteria to multiply, thus increasing the risk of exposure. HSE adds, “It is a simple fact that the organism will colonise both large and small systems so both require risks to be managed effectively.”
One reason behind the rise could include more reporting, says Dr Richard Russell, medical adviser to the British Lung Foundation. He explained, "The infection itself causes symptoms of pneumonia: fever, cough and breathlessness. Sputum production is often variable. The diagnosis of legionella pneumonia is made using a specific blood test which detects antibodies to the bacteria in the blood. One of the key issues with an increase in diagnosis of this infection is perhaps that doctors are looking for it more often.
"The guidelines into the management of pneumonia do recommend testing for legionella, but this guidance is not always followed. Thus, an increase in diagnosis may follow if doctors actually test more. This is not a bad thing as previously reported rates may be under-representative of the true level of infection."
Reducing the risk of Legionnaires' disease
So what areas need to be checked, maintained and tested in order to avoid the risk of Legionnaires' disease? You will need to consider:
Cold water storage – storage tanks, water temperature, external contamination and build-up of scale
Cold water outlet, eg taps and showerheads – water temperature and descaling to avoid build-up of ‘food’ for the bacteria
Hot water systems – the cylinder/calorfier must be cleaned and kept free of contamination or build-up of sludge and scale. Water temperature (outgoing) should be at least 60ºC to kill off the bacteria
Pipework – avoid long pipe runs and heat transfer from other sources, in the case of cold water pipes
‘At risk’ population – If guests' immune systems are compromised they are consequently classified into the “at risk” group.
Dr Nick Phin, Deputy Director of National Infection Service at Public Health England, said, “Man-made water systems that have not been designed to adequately control legionella and/or are badly maintained have increased potential to be a source of a Legionnaires’ disease outbreak.
"Legionella bacteria can survive in artificial water systems if there is a combination of different factors, including the age of the building, design of the water system, and water temperatures. We advise facilities managers to follow the Health & Safety Executive’s code of practice on preventing Legionnaires’ disease.
“Some groups are at greater risk of Legionnaires’ disease such as people who smoke and those with long-term health conditions. 74.6% of cases in 2016 reported at least one underlying health condition or risk factor.”