An outbreak of Pontiac fever related to whirlpool use, Michigan 1982

Fourteen of 23 female members of a church group experienced an acute self-limited illness characterized by chills, fever, chest pain, cough, and nausea, consistent with the diagnosis of Pontiac fever. All 14 affected women had used a whirlpool located in the women's locker room during a racquetball party.Legionella pneumophilaserogroup 6 was isolated from the women's whirlpool. Nine of 14 cases showed a seroconversion to heat-fixed antigen prepared from theL pneumophilaserogroup 6 isolate. Aerosol size studies show that the whirlpool aerator produced water droplets small enough to travel deep into the tracheobronchial tree but large enough to transportL pneumophila. This outbreak demonstrated that Pontiac fever may be associated withL pneumophilaserogroup 6, that whirlpools can serve as a reservoir for these organisms, and that seroconversion can occur in the absence of illness. (JAMA1985;253:535-539)