Legionnaires' Disease
Legionnaires' Disease is the most serious of three clinical conditions caused by legionella bacteria, which are present in the majority of both natural and man-made water systems. It is a severe form of pneumonia, which, while relatively rare, can cause severe morbidity and mortality in vulnerable populations. If acquired in hospital, Legionnaires' Disease adds significantly to the overall cost of medical care.
Legionella Background
Legionella bacteria are present in both natural and man-made water systems, and begin to grow when given the correct conditions of temperature and nutrients. Unfortunately, many common industrial and commercial water services provide the exact conditions that the bacteria require for growth.
When Legionella bacteria are present in high numbers in water sprays or droplets 3 - 5 microns in diameter, these can be inhaled into the lungs where they cause Legionnaires Disease. There is no evidence of disease from drinking contaminated water or absorption through the skin. High risk areas are therefore associated with showers, sprays, spray taps, taps with high water pressure, and refrigeration and air-conditioning cooling towers.,
Conditions within water systems that allow the proliferation of Legionella include stagnation within tanks and pipes, dead-legs in pipe work, temperatures between 20 and 45oC, poor calorifier maintenance, and insufficient and infrequent disinfection of water tanks and pipework. To reduce the risk of Legionnaires Disease, steps must be taken to avoid these conditions.
Legionnaires Disease first sprang to attention in the mid 1970’s and is caused by Legionella pneumophila serogroup 1 (One of 14 identified groups of legionellosis). LP sero groups one and six are associated with illness in man.
Legionnaires Disease is similar to a severe form of pneumonia, the symptoms may include breathlessness, coughing, chest aches, headaches and feeling generally unwell. Legionnaires Disease has a low attack rate but with a high mortality rate of around 15%.
Incubation periods for legionellosis are usually 3 to 5 days but can be up to 10 days. When diagnosed all forms of legionellosis respond to treatment with antibiotics. However as with most diseases it is more serious in the elderly and children, and people whose immune systems are suppressed in some way (such as hospital patients). Smokers are also known to be at a greater risk from Legionnaires Disease
Although cooling towers are often incriminated in large outbreaks, it is often the domestic potable water supply, and particularly the hot water systems in larger buildings, that are linked with the majority of reported cases of Legionnaires Disease. Again, inhalation of aerosols created by showers and taps are believed to be the main route of transmission.
Legionella & the Law
There are few who would deny that there are substantial financial pressures on the budgets of every Facilities Manager – so why spend money on Legionella control? First and foremost, a documented Legionella Control strategy is not an option – it is a requirement for any premises covered by the Health & Safety at Work Act. A well set out Legionella control program also gives many economic benefits, including increased heat-exchange efficiency, better water quality and the opportunity to reduce hot water temperatures.
The consequences for non-compliance are severe. The building owner and “responsible person” (most often the facilities manager) are personally liable for non-compliance, and can face criminal charges and imprisonment in the event of deaths being caused.