CHARACTERISTIC OF COMBINED NATURAL FOCI OF DISTOMIASIS IN THE ECOSYSTEM OF THE LOWER STREAM VAGAJ RIVER (TYUMEN REGION)

Abstract

In the ecosystem of the lower stream of the Vagaj river is established the presence of natural foci of opisthorchiasis, metorchisiases (Metorchis bilis, Metorchis xanthoso-mus), rhipidocotyliasis and paracoenogonimiasis forming 10 types of combined foci. The combination of natural foci of trematodes in the presence of common hosts of the pathogen in nine types of combined foci is predetermined by the formation of parasitocenosis between hemypopulations of the parasite and populations of hosts, and in one combined focus – parasitocenosis in parasitic systems. At the same time, these parasitic systems of agents form infestation-infestation population-combined and system-combined foci. 6 sites of the river bed and 12 floodplain reservoirs have been searched for the presence of mollusks – the first intermediate hosts of trema-todes. Malacofauna of the reservoirs is represented by 10 species of mollusks. Their number is extremely variable and varies from the complete absence of some species to 15–20 specimens/m2Limnaea stagnalis and Anodonta cygnea. 988 youngs-of-the year, 219 of one-year old, 118 – two years old and 14 – three years old fishes of the family Cyprinidae, caught at 14 biotopes, have been investigated by the compressor method. Youngs-of-the year and yearlings were compressed and viewed completely. The study of the fishes showed their infestation by metacercariae Opisthorchis felin-eus, Metorchis bilis, Metorchis xanthosomus, Paracoenogonimus ovatus, and Rhipido-cotyle companula.