Epidemically and epizootically dangerous fsh species for opisthorchosis in the Novosibirsk Region

The purpose of the research is identifcation of epidemically and epizootically dangerous fsh species for opisthorchosis in the Novosibirsk Region.Materials and methods. Helminthological studies were carried out from 2002 to 2020. We studied a total of 2994 fsh specimens belonging to 8 species of Cyprinidae, carps and allies, namely, ide, Leuciscus idus (L.); dace, L. leuciscus (L.); bream, Abramis brama (L.); roach, Rutilus rutilus (L.); verkhovka, Leucaspius delineatus (Heckel); crucian carp, Carassius carassius (L.); gudgeon, Gobio gobio (L.); and minnow, Phoxinus phoxinus (L.). The fsh were identifed to species according to the fsh guide. To identify Opisthorchidae metacercariae in fsh muscles, the compressor method generally accepted in helminthology was used. The Opisthorchidae metacercariae were identifed using the freshwater fsh parasite guide.Results and discussion. Of 8 studied fsh species of the family Cyprinidae in the Novosibirsk region, the Opisthorchidae metacercariae infection was noted in 7 species (ide, dace, roach, bream, verkhovka, gudgeon, and crucian carp). The following Opisthorchidae species were recorded in the studied fsh: O. felineus, M. bilis, M. xanthosomus, and Metorchis spp. The O. felineus metacercariae were most often found in the supplementary host, in 12.9 % of cases, and M. bilis, M. xanthosomus and Metorchis spp. larvae were found much less often. In terms of epidemy, the ide and bream having large commercial sizes are the most dangerous: the ide as the most heavily infected species, and the bream as the most often caught and eaten by humans. Small non-commercial fsh (the dace, roach, verkhovka, as well as the small ide and bream) are of great epizootological importance, since they are used for food for domestic and wild animals most often. Infected fsh were only found at unregulated marketplaces; the infection prevalence in the roach was 35.5%, of which 22.6% were affected by O. felineus metacercariae, and 12.9% by M. xanthosomus metacercariae.