Environmental survey of Legionella pneumophila in hot springs in Taiwan.

Acquisition of sporadic community-acquired legionnaires' disease has been linked to hot springs and whirlpool baths. Outbreaks of hot spring-associated legionnaires' disease were reported in Japan in the last few years. Although the mode of transmission is unclear, the presence of Legionella in hot springs may discourage hot springs resort visits by the general public. An environmental survey was conducted to determine the presence of Legionella in hot springs in Taiwan. In total, 55 water samples were collected from 19 hot springs resorts; 21% (4/19) of the hot spring resorts sampled yielded L. pneumophila in the public hot springs bath. Legionella pneumophila serogroups 1 and 6, L. pneumophila serogroup 3, L. pneumophila serogroup 5, and L. pneumophila serogroup 7 were isolated from four different resort spas, respectively. The total sample positivity rate for L. pneumophila was 11% (6/55). The risk of occurrences of legionnaires' disease outbreaks associated with hot springs water in general public is unknown, and epidemiologic investigations should be conducted for locating the potential sources of Legionella for those cases of community-acquired legionnaires' disease. Disinfection of hot springs for Legionella may be necessary if the risk of contracting legionnaires' disease from hot springs can be validated by an evidence-based approach.