Epidemiological Situation on Tick-Borne Viral Encephalitis in the Russian Federation over the Period of 2015–2024 and Short-Term Incidence Forecast for 2025

The aim of the review is to conduct a comparative analysis of the epidemiological situation on tick-borne viral encephalitis (TBVE) in the constituent entities of the Russian Federation in 2015–2024 and to provide a forecast of the incidence rate for 2025. According to the data for 2015–2024, the number of visits to medical organizations by people that suffered from tick bites remained approximately at the same level and averaged 491,871.2 cases per year. The Siberian, Volga, and Ural Federal Districts are of primary importance for the formation of the incidence rate, accounting for more than 75 % of all cases. In 2024, 1 659 patients with TBVE were identified, which is only slightly less than in the previous year (1 778). The morbidity rate per 100 thousand population (1.13) was lower than the long-term average for the period of 2015–2024 (1.17). 46 lethal outcomes were registered (mortality rate 2.7 %), which is 1.3 times higher than the long-term average. The epidemic process in 2024 was most active in the territories of 11 entities of the Russian Federation: Krasnoyarsk and Perm Territories, Sverdlovsk, Kirov, Irkutsk, Novosibirsk and Kemerovo Regions, TransBaikal Territory, St. Petersburg city, Udmurt Republic, and Arkhangelsk Region. The number of virus containing ticks removed from people and from environmental objects, when studied using PCR and ELISA, in the Russian Federation as a whole in 2024 did not exceed the long-term average value. The infection rate of ticks removed from people has statistically significantly decreased over a ten-year period. The review examines the volumes of specific and non-specific TBVE prevention measures taken in Russia in 2024 and compares them with the data from previous years. It is predicted that the situation on TBVE incidence in 2025 will remain at the average long-term level in six federal districts of the country. However, in the Far Eastern Federal District, mainly due to the change in the epidemiological situation in the TransBaikal Territory, a statistically significant trend towards an increase in the morbidity and mortality has emerged, which is taken into account when making the forecast of the TBVE incidence rate for this federal district in 2025.

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