[An outbreak of Legionnaire's disease associated with a Japanese spa].

From June 24 to July 5, 1996, 3 patients were admitted to the same hospital with atypical pneumonia. One of the patients, a 52-year-old man, demonstrated progressive pulmonary infiltrates and severe hypoxemia, and finally required mechanical ventilation. All 3 patients had elevated antibody titers for Legionella pneumophila serogroup 1, and had visited the same spa prior to the onset of their symptoms. On September 25, 1996 the district health department inspected the spa, and isolated Legionella pneumophila serogroup 1 from the facility's hot water tanks and outlets. Although it has been reported that many spas in Japan are contaminated with Legionellaceae, the outbreak we encountered suggests that Japanese spas, like whirlpool spas in Europe and North America, can be a source of Legionnaire's disease.