Legionella bacteria can be found wherever there is water and spa pools are no exception. New research from the UK Government funded Health Protection Agency (HPA) has shown the risk to be greater than previously believed.

HPA research shows:

• In 2003, there were 27 cases of Legionnaires’ disease associated with Spa pools in England, three of those cases were fatal.
• More than a quarter of all spa pools tested in the study proved positive for Legionella bacteria.
• Spa pools that passed tests for E. coli, coliforms and Pseudomonas aeruginosa were still positive for Legionella.

Other types of bathing waters can also contain Legionella. A new born baby contracted Legionnaires’ disease from a birthing pool, but spa pools pose the greatest risk. High numbers of bathers in relatively small volumes of water puts an increased strain on the pool disinfectant regime. In addition the water is agitated thus increasing the rate at which skin cells (with their associated bacteria) and other organic matter is released into the water; the disinfectant has to cope with this extra load. Finally spa pools often run at elevated temperatures suitable for the multiplication of Legionella. If the disinfectant is struggling to cope with the demands of the pool, high levels of Legionella can occur.

Once Legionella has established a foothold in the system, infections are likely to occur because the organism is released into the air by the aeration of the spa itself. Risks are further increased due to the close proximity of bathers and bystanders, and it is not surprising to find susceptible people are often linked with contracting legionella associated infections from spas.

How to reduce the risks

• Always carry out a risk assessments for pools. Risk assessment services are available commercially. Choose a risk assessor that is a member of the code of conduct scheme.
• The HPA are calling for the testing of spas for Legionella to become mandatory. Failure to carry out regular tests means failing to identify the risk.
• When choosing a laboratory to test for any microbiological parameter, it is recommended that the laboratory is accredited by The UK Accreditation Service (UKAS). A reliable method of testing is the culture method based on ISO11731. Some rapid methods of testing have been shown to be unreliable and usually have very high lower limits of detection.
• Operate your pool correctly at all times. The HPA publishes a book “Hygiene for Spa Pools” that offers good advice.
• Pool operators should always know and apply bather limits and remember never to overload pools.
• Always monitor the condition of the pool’s disinfectant regime and water quality frequently – every 2 hours. Test for biocide level (free and combined), pH, total dissolved solids and understand what these values mean.
• Correctly written procedures will recommend what to do if limits are breached – procedures must be followed when incidents occur. Ensure relevant members of staff are properly trained.

Legionnaires Disease is a primarily a preventable infection and as such precautions should always be taken. Sensible measures to reduce the risks significantly are often effective and inexpensive. The consequences of failing to act are profound – death, disability and possible legal action against the operator. Don’t get caught out!

 

Article by:
Gary Hogben
Laboratory Manager
Feedwater Ltd.
T: +44 (0)151 606 0808
E: Gary.Hogben@feedwater.co.uk