[Detection of an increase in the proportion of tick-borne encephalitis virus-infected Dermacentor marginatus Sulz. among active females of older physiological ages].

Numbers of active females of Dermacentor marginatus ticks infected parenterally with tick-borne encephalitis virus are compared. Increase in this proportion is demonstrated with ticks' physiological aging. Epidemiological and epizootic importance of the discovered phenomenon are the increase in the probability of persistent virus circulation throughout the season, since only active individuals are capable of virus transmission. Besides, it is among them that the virus is most frequently found in saliva.