Epizootiology of Opisthorchiasis in Carnivores, Fish and Mollusks in the West Kazakhstan Region

Investigating the infestation of opisthorchiasis in domestic animals can help identify areas with high infection rates and develop targeted control measures to reduce transmission. The work aimed to study the opisthorchiasis infestation in domesticated carnivores (dogs and cats), fish of the Cyprinidae family, and mollusks to identify their infestation status. The study was carried out in the coastal villages of the Ural River in the West Kazakhstan region in 2021-2022. It was found that the infestation extensity of Opisthorchis felineus infestation averaged 89.7% and the infestation intensity was 19.6±1.6 units/animal in dogs and 97.9% and 34.4±2.9 units/animal in cats, respectively. A high fish infestation by O. felineus metacercariae in the family Cyprinidae was noted. The infestation extensity and infestation intensity averaged 70.4% and 22.6 metacercariae/specimen, respectively. The maximum infestation rates were recorded in the ide. During the study of fish infestation with Opisthorchis metacercariae, an increase in infestation with age was found. The maximum infestation intensity in ide reached 340 metacercariae per specimen at 3 years. The population density of mollusks of the genus Bithyniidae in the reservoirs of the middle Urals basin was 5.1 specimens/m2 and the infestation with O. felineus cercariae was 5.7%. The epizootological conditions of the middle Urals basin were unfavorable concerning the opisthorchiasis infestation. In the coastal settlements of the Ural River, domesticated carnivores are infested with O. felineus. In the reservoirs of the middle Urals basin, fish from the family Cyprinidae and mollusks and the genus Bithyniidae are infested with Opistorchis larvae.