In this research we studied the dynamics of infestation of ticks with European and Siberian isoforms of tick of tick-borne encephalitis virus collected from 2007 to 2016 from vegetation cover, domestic animals and clothes in Kirov, Kirovo-Chepetsk, Orychevsky, Zuevsky, Slobodsky and Turinsky districts of Kirov Oblast. All collected samples were analyzed for the presence of tick-borne encephalitis virus in them. The virus isoforms were detected by reverse transcription - polymerase chain reaction (RT-PCR). The analysis revealed the dynamics of the percentage of ticks infected with isoforms of tick-borne encephalitis virus. In the central regions, which share common borders, it was revealed the coincidence of the peaks of infection with the European isoform virus, but further studies are needed to determine the periodicity. It was also noted that for some areas, the maximum peak of infection and the increase in the time between peaks are characteristic. A low percentage of contamination in the territory of Kirov city could be associated with treatment with acaricides. Since 2011, in the Kirov region, there have been cases of ticks infected with tick-borne encephalitis virus from the Siberian isoform. Every year there is an intensive penetration of the Siberian isoform westward through the territory of the Kirov Region. Periodicity of peaks is approximately 3 years.