Risk of infection associated with microbiological quality of public swimming pools in Bologna, Italy.

Twelve public swimming pools in Bologna (Emilia-Romagna region, Italy) were investigated for the microbiological quality of water and surfaces of the pool edges, showers and changing rooms. At the same time a cross-sectional study was carried out on the health of 238 users (bathers) compared with 238 controls who practised sports other than swimming. Data regarding duration and frequency of exposure, behaviour and recent medical history were gathered by means of a questionnaire. All participants also underwent a medical examination. Compliance of the pool water to the microbiological standards set by Italian regulations was generally good; compliance was total when free chlorine residual was within the recommended limits. However, when analysis was extended to the various surfaces, potentially pathogenic bacteria such as P. aeruginosa and C. albicans were isolated. Eye burning and diarrhoea were the only declared symptoms and verrucas the only diagnosed disease showing statistically significant differences between bathers and controls. Verrucas tended to increase in proportion to exposure. Athlete's foot had a very high prevalence among both bathers (34 %) and controls (27.3%) and controls (27%). The environmental and epidemiological investigations both confirmed the risk of infection, mainly associated with the contamination of surfaces.