Ixodid ticks and tick-borne encephalitis virus prevalence in the South Asian part of Russia (Republic of Tuva).

The most significant processes of arbovirus evolution can be expected to occur in the territories where ticks of different species cohabitate and at the boundaries of virus occurrence, where the probability of the appearance of new virus variants is high due to the possible shift in the main vectors and/or vertebrate hosts. One of the most interesting regions in this regard is the Republic of Tuva. Since most of its territory is covered by mountain ranges and intermountain basins, we were able to study the distribution of vectors and viruses in geographically isolated areas at different altitudes and in various landscapes.

[Results of 20-year observations of changes in the size of an Ixodes ricinus (Acari: Ixodes) population and a change in its infection with tick-borne borreliosis pathogens in the north of the Kaluga Region].

The paper shows changes in the size of Ixodes ricinus ticks population and their infection according to the results of their 20-year systematic collections and censuses on the same routes in the Zhukovsky District, Kaluga Region. It has been established that there are always some infected I. ricinus ticks in the season of their activity (April to September).

Distribution of Ixodes ricinus and I. persulcatus ticks in southern Karelia (Russia).

The northern boundary of the sympatric zone of Ixodes persulcatus and I. ricinus (Acari: Ixodidae) passes through Karelia. Studies carried out in the 1950s showed that these Ixodes species were mostly found in southern Karelia.

Different tick-borne encephalitis virus (TBEV) prevalences in unfed versus partially engorged ixodid ticks--evidence of virus replication and changes in tick behavior.

There is some evidence that tick-borne encephalitis virus (TBEV) prevalence in ticks, removed from humans, is higher than that in field-collected ticks from the same area. There are two possible explanations: (i) Infected ticks are more active and aggressive and can be found on humans more often. (ii) Some questing ticks are infected with TBEV in a low, undetectable concentration; during tick feeding, virus replicates and reaches the titers that can be detected.