[Ecological bases of the combination of natural foci of leptospirosis, tick-borne encephalitis, and ixodes tick-borne borrelioses in the ecosystems of a northern forest-steppe subzone in the Tyumen region].

In the context of the present-day teaching of parasitocenoses and the proposition that the pathogen's population is the only compulsory and specific component of a natural focus, the authors bring to light the ecological bases of the combination of natural foci of leptospirosis and tick-borne encephalitis, leptospirosis and Ixodes tick-borne borrelioses. These foci are one-host population-combined. While analyzing the combination of the foci, it is expedient to consider in pairs since this provides a way of identifying the combination bases that are unique to these foci and determining the level, pattern, type, and degree of the combination of foci and, on their basis, the type of a combined focus. By determining the confined pattern of foci of leptospirosis, tick-borne encephalitis, and Ixodes tick-borne borrelioses to the same elements of a landscape, the morphological structure of the northern forest-steppe landscape of the Tyumen Region predetermines their relationship, by acting as the abiotic basis of the combination of foci. Despite the differences in the types of the parasitic systems and the absence of the same mechanism of transmission of causative agents, the natural foci of leptospirosis, tick-borne encephalitis, and Ixodes tick-borne borrelioses are, nevertheless, combined at the level of parasitocenosis of the co-acting populations of pathogenic organisms and their reservoir hosts act as the biotic bases of the combination of foci of leptospirosis, tick-borne encephalitis, and Ixodes tick-borne borrelioses. The susceptibility of Cl. rutilus and S. araneus to infection with the pathogens ofleptospirosis, tick-borne encephalitis, and Ixodes tick-borne borrelioses and multihost pattern of the causative agents act as the epizootic bases of a combination of the foci of leptospirosis, tick-borne encephalitis, and Ixodes tick-borne borrelioses. It has been shown that the biotic, epizootic, and abiotic bases of a combination of the natural foci of leptospirosis, tick-borne encephalitis, and Ixodes tick-borne borrelioses of the Javanica serogroup are, in the aggregate, the ecological bases of the combination of these foci.