CERCARIAL DERMATITIS IN EUROPE - A NEW PU BLIC-HEALTH PROBLEM

Cercarial dermatitis is a parasitic impasse that has worldwide distrib ution. The condition manifests itself as a highly pruriginous skin ras h and is due to penetration of the dermis by larval stages (furcocerca riae) of avian trematodes. Many species may be responsible for this di sease. In Europe the genus Trichobilharzia is widely represented, in p articular by the species T. ocellata; the definitive host is the duck (Anas platyrhinchos); the intermediate hosts are snails of the genus L ymnea (L. ovata or L. stagnalis). In France, cases of cercarial dermat itis were reported in June and July 1994 to the health authorities of three departements in the Pays de la Loire Region (western France). Th e epidemiological situation, common to the three maintained ponds that were concerned, is as follows: high level of eutrophication of the si tes, colonization of the ponds by L. ovata, and settlement by many duc k colonies. The simultaneous occurrence of these three phenomena, comb ined with long hours of sunshine in the summer, is responsible for mos t of the foci of cercarial dermatitis recently described in Europe. Co ntrol of this condition is difficult, requiring strict maintenance of bodies of water and if necessary the use of molluscicides such as nicl osamide. The use of praziquantel in baits for treating the definitive hosts appears to interrupt the natural cycle of the avian Schistosomat idae. In the light of the observations reported here and the analysis of recent publications, cercarial dermatitis may be regarded as an eme rging disease. Its public health impact needs to be evaluated at the g lobal level.