Emergence of tick-borne zoonoses from the standpoint of the theory of natural focality of infections.

The term "emerging infections," which has been applied to all the diseases characterized by increasing incidence, has only a formal sense because "emerging" is only a temporary stale of epidemic manifestation of a disease. The factors responsible for the appearance of emerging (or re-emerging) diseases with different ways of transmission and ecological peculiarities of their agents (e.g., anthroponoses, zoonoses, sapronoses, and other groups) are absolutely different. Pathogens of diseases with natural focality are natural components of ecosystems. Natural foci of tick-borne infections are characterized by long-term existence in a certain territory, and their state, among other factors, depends on conditions necessary for the existence of the main vector population. Parameters of morbidity caused by infections with natural focality are contingent upon the interaction of factors determining the epizootic activity of natural foci and the intensity of people's contact with them. A principal scheme of the interaction of various biotic, abiotic, and social factors determining the level of epidemic manifestation and emergence of tickborne diseases is presented.