[Otitis externa among users of private swimming pools]

The purpose of this study was to detect risk factors for developing otitis externa (OE) with special regard to swimming in private pools in holiday houses. Data were collected in a retrospective case-control study from June to October in 1993 and over the same period in 1994. Patients who had OE diagnosed by a general practitioner were included. In 1993 controls were 134 guests from 27 holiday houses where nobody got o.e. during their stay. The number of cases was 35. In 1994 the design was changed so that controls were the 95 healthy inhabitants from the same houses as the 23 cases. The amounts of time spent in the pools and the total bacteria count in the water were significant risk factors for developing OE. Pseudomonas aeruginosa was found in 80% of the ear swabs of the casegroup. In 1993 30% and in 1994 83% of the pools fulfilled the requirements for public pools set by the Danish authorities.