Chapter 54 : Prevalence of Legionella in Whirlpool Spas: Correlation with Total Bacterial Numbers

Abstract:

The purpose of the current study was to determine the prevalence of Legionella species in public whirlpool spas (in the absence of disease) by examining a large population of these spas over the past 18 years. Additionally, the presence of Legionella was correlated with other microbiological parameters, including the presence of another disease-causing bacterium (Pseudomonas aeruginosa) that may be transmitted via whirlpool spas, and the total bacterial numbers as a measure of the overall microbiology and disinfection status of the spas. A similar relationship was found between P. aeruginosa and high total bacterial counts. On the basis of these results, it would appear that Legionella and P. aeruginosa proliferate primarily in spas where the disinfection (i.e., free halogen concentrations) and other maintenance procedures are inadequate to control the total bacterial numbers. In conclusion, the current data would support a conclusion that Legionnaires' disease is a preventable illness, at least as associated with whirlpool spas. Prevention of disease would be related to tight control of free available halogen levels and other regular maintenance procedures, coupled with bacterial monitoring to assess the effectiveness of these procedures.