2023 Volume 59 Issue 2 Pages 17-25
Many outbreaks of Legionnaires’ disease have been reported from cooling tower water overseas, but in Japan, bath water is the most common source of Legionnaires’ disease infection. Although the Ministry of Health, Labour and Welfare has issued a series of notices to promote the improvement of hygiene management standards, outbreaks of Legionnaires’ disease caused by hot spring facilities are still occurring.
The Tokyo Metropolitan Government’s regulations regarding sanitation of public bath that Legionella bacteria must be “not detected” in water. In the Tokyo’s regulations, the term “not detected” actually means that the concentration of Legionella bacteria must be less than 10 CFU/100 mL . If Legionella bacteria exceed 10 CFU/100 mL in bath water, the Tokyo Metropolitan Government （TMG） recommends improving sanitation of the facilities.
This present paper introduces the Legionella testing methods conducted by the TMG and reports on survey of Legionella bacteria in 2,072 bath water samples from facilities in Tokyo that were inspected by the government from FY2018 to FY2020.
