Men who participated in a handball tournament and used a spa pool in the men's locker room became ill with fever, chills, malaise, and headache. The handball tournament was held at a recreation center in Columbia Heights, Minnesota on March 4 and 5.

Minnesota Department of Health staff interviewed 73 individuals. Forty-eight met the case definition. The median incubation period from the first exposure to the recreation club was 44.5 hours (range, 15 to 73.5 hours). One person was hospitalized overnight. No one died. Being in the men’s locker room the evening of March 4 was significantly associated with illness (43 of48 cases vs. 0 of 23 controls; odds ratio, undefined; p < 0.001).

Six patients had a specimen collected for a Legionella urinary antigen test. All six specimens were negative.

Anoka County Community Health and Environmental Services (ACCHES) staff visited the facility and confirmed there was an unlicensed spa pool in operation in the men's locker room. There was no history of the spa pool being recently chlorinated or otherwise disinfected. Cracks and corrosion were observed on the spa pool surfaces.

Symptoms, incubation period, and high attack rate are consistent with Pontiac Fever, a milder illness caused by Legionella bacteria. The improper maintenance and lack of disinfection of the spa pool likely led to the proliferation of the bacteria. Ventilation problems may have allowed aerosols to spread outside the men's locker room.