In 2005, we dissected 102 wildfowl from the Czech Republic and 73 wildfowl from Poland including representatives of Anseriformes, Gruiformes and Gaviiformes. Schistosome infection was found in a total of 21 (29%) and 23 (23%) birds from Poland and the Czech Republic, respectively. All infected birds belonged to the order Anseriformes. The prevalences of nasal and visceral species were, respectively, 22% and 16% in Poland and 6% and 19% in the Czech Republic. Four species of schistosomes were found: Bilharziella polonica Kowalewski, 1895, Trichobilharzia regenti Horák, Kolářová et Dvořák, 1998, T. szidati Neuhaus, 1952, and an undetermined schistosome from the intestinal wall of Anas penelope L. The finding of T. szidati represents the first record of the parasite from natural final host since the species description.
F.xcept other functions, surface saccharide residues on trematode larvae are supposed either to be the targets of the intermediate (molluscan) and final host immune systems, or to represent candidates for molecular mimicry. Therefore, changes in surface saccharide patterns during the development of the avian schistosome Trichobilharzia szidati were characterized. Whole parasite larval stages and their tissue sections were examined using FITC-conjugated lectins. Marked surface differences were found among larval stages (miracidia, mother sporocysts, daughter sporocysts, cercariae, schistosomula). Staining by some lectins reflected known ultrastructural changes of the outer tegument. Reaction of lectins with cercarial embryos was almost negative. In case of other developmental stages, binding of at least one member from each carbohydrate-specificity group of lectins (Man/Glc-, GIcNAc-, Gal/GalNAc- and Fuc-specific) occurred. One exception is represented by mother and daughter sporocysts which practically failed to react with Fuc-specific lectins. Besides other lectins which recognized larval surfaces, a-L-fucose-specific lectins (LTA, UEA-I) and (GlcNAcfll —>4)„-spccific WGA bound very strong to certain stages. The comparison of mature intrasporocystic cercariae with those emerged from snails brought the indication that some snail glycosylated molecules adhere to the surface of schistosome larvae or that emerged cercariae express some new carbohydrate epitopes under changed environmental conditions. The result partially supports the theory of parasite mimicry/masking strategies and immune evasion in the host.