Duration of whirlpool-spa use as a risk factor for Pseudomonas dermatitis.

Pseudomonas dermatitis occurred among 16 of 49 whirlpool-spa bathers in a Vermont hotel during a weekend in November 1983. Pseudomonas aeruginosa, serotype 0:4, was isolated from a patient and the whirlpool-spa water. Since duration of whirlpool-spa use had been previously postulated as a risk factor for dermatitis, a historical cohort study was designed to test this hypothesis. Each bather was carefully interviewed about the duration in minutes of whirlpool-spa and swimming pool exposure on the weekend. Total duration of whirlpool-spa use was significantly associated with rash illness both on contingency and logistic regression analysis. Females were also found to be at increased risk, after controlling for the study hypothesis. Duration of whirlpool-spa use was an important determinant of risk for Pseudomonas dermatitis in this outbreak.