[Natural foci of tick-borne encephalitis on the southwestern coast of Sakhalin].

Nucleic acids of Ixodes persulcatus were studied by molecular hybridization in the natural focus of tick-borne encephalitis in Kholmsk District of Sakhalin Province. The studies have shown wide dissemination of viral RNA in the focus. The infectivity of ticks in various sites of habitation varied from 3.5 to 18.5%, their number fluctuating from 0.4 to 300 and more imago per flag-hour. The most active part of the natural focus has been determined using zoological-viral indexes. The viral strain of tick-borne encephalitis has been isolated.