[An outbreak of Pontiac fever among children and adults following a whirlpool bath].

We investigated an outbreak of fever most likely due to a contaminated whirlpool among nine adults and six children visiting a holiday home. The outbreak was characterized by a high attack rate, short incubation periods, influenza-like symptoms and rapid recoveries typical of Pontiac fever. The children, however, experienced less characteristic symptoms and no sequelae compared to the adults. Evidence and presumptive evidence of Legionella (L) infection was found in eleven cases; in one case by isolation of L. pneumophila serogroup 1, in two cases by positive test for Legionella by PCR and in eleven cases with seroconversion. In contrast, two adult non-users of the whirlpool had no symptoms and no serological evidence of infection. This investigation demonstrates differences between adults and children in the clinical picture of Pontiac fever, furthermore it shows that culture and PCR of tracheal aspirate for legionellae can be used in a hospital setting for rapid diagnosis although their sensitivities are low.