[Human cercariasis caused by schistosomatid larvae from aquatic birds in the Narochanka River recreational area of Byelarus].

The reasons of the dramatically aggravated cercarial situation were examined in the Naroch Lake area (Minsk Province, Byelorussia). The incidence of infection with cercariae of the family Schistosomatidae trematodes in 8 mollusk species of the genera Lymnaea, Planorbarius, Planorbis, Anisus which were nonuniformly distributed in the upper littoral were studied. The snails form mosaic congestions of various density (from solitary individuals in a 50-100 m2 area to hundreds per m2), which is associated with the nature of aquaphytocenoses and the degree of plant overgrowth. The snails infected with Trichobilharzia ocellata and Bilharziella polonica cercariae accounted for 18.8%. Schistosoma cercariae affected L. stagnalis, L. ovata, and L.p. corvus to the greatest extent. The proportion of ducks (Anas platyrhyncha) infected with the two Schistosomatidae is 30.0% in the area in question with the average infestation rate of as many as 20 trematodes of both sexes per duck. High-risk areas for human infestation (with the number of Schistosoma cercariae exceeding 10 larvae in 10 liters of water) were recorded in the upper littorals in the beach zones of all recreation institutions such as sanatoria, rest homes, camping, etc.). The fact that Schistosoma cercariae can be active in attacking man under the conditions of the Naroch Lake littoral was verified by the self-infestation of one of the authors (S.A. Be'er). Schistosome dermatitis showing its typical clinical manifestations developed after 120-130 cercariae had penetrated into the arms and legs.(ABSTRACT TRUNCATED AT 250 WORDS)