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Legionella (Legionnaires’ disease) and Drinking Water Quality
Frequently Asked Questions:
What is Legionnaires disease? It is a form of atypical pneumonia that is only contracted when people who are suscepticable due to old age, or underlying ill health are exposed to aerosols containing the bacteria legionella. Other non life threatening infections include Pontiac and Logiolhead Fevers which cause flu-like il nesses that people recover without hospital treatment in about 5 days. Is Legionnaires’ disease rare? No it’s not rare but most cases are not detected and not all cases detected are reported to the Health Protection Agency. Since most cases only involve one person (65 to 80% of cases) they receive little publicity and it is almost impossible to ascertain where such individuals have contracted the disease. Who is at risk of contracting Legionnaires’ disease? The risk of catching legionnaires’ disease is based on two key factors: the number of legionella bacteria breathed in and the resistance of the individual to infection. Young and apparently healthy people can get Legionnaires’ disease, but persons who are immunocomprised either because of illness (e.g. c ancer patients) or medical treatment (e.g. chemotherapy) are at a much higher risk because they can be infected by relatively low numbers of legionella bacteria. HIV infected patients, for example have a 40 fold increased risk; organ transplant patients have a 200 fold increased risk. Smokers and persons over 65 years of age ,and heavy drinkers have moderately higher risks. How is legionnaires’ disease treated? Early treatment reduces the severity and improves chances for recovery. In the Barrow in Furness outbreak less than 5% infected died. Previously this would have been between 10 to 12% but early diagnosis led to lives being saved. The antibiotics of chioce are clarithromycin and erythromycin. What water conditions promotes the growth of legionella bacteria? Warm (temperatures between 20 °C to 50°C) the organism can multiply with 36°C being the optinum temperature for growth. The present of corrosion,scale or other bacteria provides nutrients and protection for legionella bacteria to colonise a water system. What types of water facilities are of greatest concern? Aerosols from Cooling towers and Evaporative Condensers, misting devices, showers, whirlpool spas, and any device where legionella is liable to grow and during normal operation, breakdown or maintenance procedures fine aerosols are likely to be created. Can Legionnaires’ disease be prevented? Yes provided a proper risk assessment to HSE L8 standards: The control of legionella bacteria in water services; that looks at all the facilities present; that visualises where the organism is likely to grow;and demonstrates an understanding of which facilicities, when in operation (i.e. normal,abnormal use, breakdown or during maintenance procedures) will generate aerosols and most importantly shows an understanding of who will be at risk in such circumstances of inhaling the contaminate droplets and contracting the disease. Then by instigating the appropriate system modifications, controls (including temperature, and chemical if appropriate) and by avoiding stagnation either by design or by flushing procedures if necessary and by keeping sall ystems free from scale and corrosion risks can be minimised. Is there legislation that requires my employer to provide safe drinking water? Yes in the UK The Workplace Health, Safety and Welfare Regulations covers this requirement. It requires that an adquate supply of “wholesome drinking water” is provided for all persons at work in the workplace. Who makes sure what comes out of the drinking water tap is safe? In the England and Wales the Drinking Water Inspectorate have this task. They annually assess the quality of drinking water supplied by the water companies and carry out individual inspections. The water companies themselves carry out millions of tests to ensure the water is safe. However from the point that the water reaches your employers building it becomes their responsibility. What is “wholesome drinking water” ? The Government has set legal standards for drinking water in the “Water Quality Regulations”. These standards define the high quality expected in terms of levels of chemicals al owed to be present, metal content, the way the water looks, smells and tastes and the levels and types of bacteria allowed to be present. IS bottled or vended water safer than the mains supplies? When tested neither have proven as clean or safe as the mains supply. However which source is used problems have been experienced and vigilence by monitoring water quality is required in the workplace.

Source: http://www.tersusgroup.co.uk/docs/Legionnaires-Disease-and-Drinking-Water.pdf