[Decreased humoral immunity to the tick-borne encephalitis virus in the population of the western Urals].

A serological survey of the human population in the western Urals in 1966-1968 and repeated survey in 1988-1989, the decrease in humoral immunity to tick-borne encephalitis virus in all age groups of people was established in most of landscape subzones of the region. The most expressive decrease of humoral immunity was noted in middle-aged people living in the subzone of broad-leaved and coniferous forests and forest steppe.