Fifteen cohorts of healthy bathers were recruited at four Lake
Leman beaches between 3 July
and 23 August 1996 to assess the public health importance of cercarial
dermatitis in Geneva,
Switzerland. Telephone follow-up interviews were carried out after 2–7
days. Overall, 153
bathers out of 555 reported probable cercarial dermatitis at follow-up.
Median daily attack
rate was 27·7% (2·2–57·7%). Of the cases,
11·1% noticed more than 30 skin lesions, 19·6%
described severe itching, 50·3% used a drug treatment, 3·9%
visited a doctor and 15% claimed
they would reduce their bathing activities. History of cercarial dermatitis,
time spent in the
water, hour of the day, barometric pressure and maximum daily atmospheric
temperature
predicted disease occurrence in multivariate analysis. While a benign disease,
cercarial
dermatitis may have a negative impact on the local water recreation industry.
The identification
of risk factors for the disease may help produce better preventive recommendations
for the
bathers.