Infection Rate of Fish of the Cypriniidae Family by Helminth Larvae of the Opisthorchiidae Family in the Seym and Psel rivers Basins in Kursk Region

Abstract

The purpose of the research is to study of the infection rate of freshwater mollusks and carp fish by trematodes transmitted by fish in the Psel and Seym basins in the Kursk region.

Materials and methods. Helminthological material was collected from caught mollusks and fish. Mollusks were explored by the methods of life-time diagnostics and compression, and the fish by the method of compressing the spinal muscles and microscopic examination according to the method commonly used in helminthology. It was examined 200 specimens of mollusks and 1030 specimens of 6 fish species from the Cyprinidae family, from underyearling to two years of age. The species composition of trematodes was determined by identification guide.

Results and discussion. Totally 4 species of helminths belonging to the Opisthorchidae: Opisthorchis felineus, Pseudamphistomum truncatum, Metorchis bilis and M. xanthosomus were identified. The extensiveness of infection by the larvae of O. felineus varied from 6.0 to 14.3 % in bleak, and 9.1% in red-eye. P. truncatum cysts were found only in bleak (8.0–11.1 %). The larvae M. bilis were found in 4 species of fish with extensiveness of infection from 5.6 to 50.0 %. 5 species of fish were infected by metacercaria M. xanthosomus (11.8–64.7 %). Epidemiological significance for humans have the first three species of the identified trematodes. The rate of fish infection indicates that the main source of opisthorchid eggs entering the examined river basins are wild and domestic birds, as well as semiaquatic mammals.