[Characteristics of the reasons for the varying epidemic manifestation of tick-borne encephalitis foci in western Siberia and the Far East].

Viral strains from the foci of tick-borne encephalitis in Western Siberia and the Far East, producing the disease which takes the clinical course of different severity, have been shown to possess similar biological properties. A high mortality rate in the foci of tick-borne encephalitis in the Primorye Territory is the consequence of the weak latent immunization of the population, which is due, in its turn, to some specific features of the epizootic process in this area.