Epidemiological and Epizootological Characteristics of Tick-Borne Viral Encephalitis and Tick-Borne Borreliosis in European Part of Russia

INTRODUCTION: Tick-borne borreliosis (TBB) andtick-borne viral encephalitis (TBVE) are widely spread in the world and in Russia and have a high socioeconomic significance. The morbidity of the population with these infections is to a large extent determined by the epizootological situation formed in the natural conditions of certain natural climatic zones.

AIM: To obtain modern epidemiological and epizootological characteristics of TBB and TBVE in the territorial formations of the European part of Russia with different natural and climatic conditions.

MATERIALS AND METHODS: The work used the materials of the Governmental reports ‘On the state of sanitary and epidemiological welfare of the population’ of the territorial departments of Rospotrebnadzor in the European part of Russia in 2012–2021.

RESULTS: The maximum incidence of TBB and TBVE (5.00 and 1.83 per 100 thousand population) is characteristic of the territory of the Northwestern Federal District (NWFD) of Russia with the natural and climatic conditions of the taiga zone. The second and third positions are occupied by the Central (4.53 and 0.34 per 100 thousand) and the Volga (3.59 and 1.11 per 100 thousand) federal districts whose territories include several natural zones. In the Southern and North Caucasian federal districts where a significant part of the territory is located in the steppe and forest-steppe zone, the incidence of TBB is 0.63 and 0.16 per 100 thousand, respectively, the incidence of TBVE is practically not recorded. The incidence of TBB and TBVE in the population correlates with the proportion of people bitten by ticks — in the Northwestern Federal District the correlation coefficient was 0.89 and 0.74, in the Central Federal District — 0.65 and 0.68, in the Volga Federal District — 0.90 and 0.92. The ratio of infection of ticks removed from people in the Northwestern Federal District with agents of TBB and TBVE was 9.7:1.0. The total annual average area of acaricide treatments has a maximum value in the Central Federal District — 14333.6 hectares. In the territorial formations of the European part of Russia with the largest acaricide treatment area, an inverse correlation was found between this indicator and the proportion of people bitten by ticks (r = -0.40).

CONCLUSIONS: The epidemiological and epizootological characteristics of TBB and TBVE in 2012–2021 in the territorial formations of the European part of Russia indicate the influence of conditions of certain natural and climatic zonesof these territorieson the formation of epizootic foci and the incidence of these infections in the population, which should be taken into account when planning and implementing anti-epidemic measures.