The risk of infestation of the population by the opisthorchiasis causative agent in the middle and lower
reaches of the Iset River was estimated. Areas with the highest risk of peoples infection by Opisthorchis
felineus’ metacercaria are identified. These territories are confined to the zones of removal of the
opisthorchiasis causative agent, which are river beds and large water bodies that constantly connect with
rivers. Steady risk of infection of the population is determined by the loimopotential of the
opisthorchiasis natural focus. The general infestation of juveniles fishes in the middle and lower current
of the Iset River made 9,9 %, annuals – 21,5 %, two-year-olds – 19,5 %.