The occurrence of a dermatitis was reported from 4 natural water reservoirs in Central Bohemia (Czechoslovakia) in June and August 1985 and 1986. The clinical course of the disease was suggestive of cercarial dermatitis. Exanthema occurred most frequently under the bathing suits of afflicted persons, and on unprotected parts of their skin as well. A total of 5,865 snails (Lymnaea auricularia) were collected at the localities Nový rybník in Príbram, Spálený mlýn at Lísnice and Uhonice. Nine individuals of L. stagnalis were collected at Grado, Celákovice. Biological examination indicated cercariae of bird schistosomes (Trichobilharzia szidati) only at one locality--Spálený mlýn, Lísnice. The question of cercarial dermatitis caused by species other than schistosome cercariae, especially by Diplostomum spathaceum which was abundant at Príbram, is discussed. Repeated outbreaks of cercarial dermatitis were stopped at one locality by chemical and mechanical snail control in a swimming pool. Chemical control by chlorinated lime and copper sulfate proved insufficient in the course of the season. The mechanical control (clearing of the mud and drying of the bottom of the pool) removed infected snails, reservoirs of the disease. Suggested changes in the composition of fish fauna should also reduce excessive reproduction of snails.

Institute of Tropical Health School of Postgraduate Medicine and Pharmacy Prague CSSR