[Prevention measures against Legionella infection in a circulating hot water bath].

For the sake of water conservation, a system for circulating hot water is widely used at public baths in Japan. Recently, large outbreaks of Legionella infection have occurred in public baths in Miyazaki and Kagoshima prefectures. More than three hundred persons were infected with Legionella pneumophila, and eight died. These outbreaks revealed that the Manual of Prevention Measures against Legionella Infection in a Circulating Hot Water Bath, which was published by the Ministry of Health, Labour and Welfare in Japan in 2001, was not fully understood or conformed to by managers of the baths. Microbiological features about legionellae should be fully understood for prevention of Legionella infection in a circulating hot water or spring bath. This review describes the microbiological characteristics of legionellae, their habits in the environment, pathogenesis, symptoms of Legionella infection, and disease outbreaks in Japan. I also describe practical prevention measures to deal with this organism in a circulating hot water or spring bath.