Infection with metacercarias Opisthorchis felineus Rivolta, 1884 (Trematoda) in some species of fish of the family Cyprinidae in the Kemerovo Region
The materials of parasitological study of fish of the family Cyprinidae in some points of the Kemerovo Region, which is located in the zone of a large West Siberian focus of opisthorchiasis, belonging to the Ob-Irtysh basin, are presented. The studies were carried out in order to detect changes in the infestation of previously studied species of fish of the family Cyprinidae in comparison with the data obtained in 2012- 2013 by students of the "Club of Beginning Parasitologists" (GUDO "Regional Children's Ecological and Biological Station", Kemerovo). To detect infection of fish with O. felineus metacercariae, the method of muscle tissue compression was used. Quantitative indicators of infestation and distribution of metacercariae were assessed using the indices: extensiveness of invasion (EI) and intensity of invasion (II). Infestation rates of fish of the family Cyprinidae slightly increased in 2021 compared to 2013: EI 25.15% and 22.58%, respectively. Out of 214 caught fish of four species: Alburnus alburnus, Rutilus rutilus lacustris, Rutilus rutilus, Carassius gibelio, the highest infestation rates were noted for R. rutilus lacustris - 58.64%, the lowest for R. rutilus and C. gibelio - 2.32% and 2.11% respectively. The total infestation of fish in the Tom River within the city of Kemerovo was 35.35%, in the Zhurgavan - 27.14%, in the Demyanovka - 18.56%. The largest number of larvae was noted in the muscles of the R. rutilus lacustris, the smallest - in the R. rutilus from the Tom River in the Zhurgavan and C. gibelio in the Demyanovka. The study of the infestation of some species of cyprinids with O. felineus metacercariae at three points in the Kemerovo Region indicates that the state of water bodies is not well enough in relation to opisthorchiasis and the likelihood of infestation of residents with this helminthiasis.