[The conditions for the possible formation of foci of diphyllobothriasis on the lower Don].

There are conditions for forming a diphyllobothriasis focus in the basin of the lower Don. In terms of the population affliction, low risk for its infection and the size of copepods, the focus is differentiated as an Oligocopepoda one of low epidemiological intensity. Its formation is favoured by the activation of the population's migration, favourable ecological and biological conditions for the existence of intermediate and supplementary hosts, the population's habit of having ill-disinfected fish, the pathways of infected material delivery into the reservoirs, the survival periods for broad tape-worm eggs, which are sufficient for diphyllobothriasis pathogens to develop their biological cycle under the conditions of Rostov Province.