The review presents an analysis of the epidemic situation on infections of rickettsial etiology, the causative agents of which are transmitted by Ixodidae ticks in the territory of the Russian Federation. The data obtained through molecular-biological verification allow to unite under the name of “tick-borne ricketsioses” a group of infections caused by R. sibirica subsp. sibirica, R. conorii, R. heilongjiangensis and other species of rickettsiae circulating in natural foci of various regions of Russia. Cases of tick-borne rickettsioses in Siberia and the Far East, caused by various species of rickettsiae, are registered under the name of “Siberian tick-borne typhus” due to the lack of available methods of differential laboratory diagnostics. The paper presents the assessment of the incidence of Siberian tick-borne typhus, indicating not only the varying degrees of epidemic hazard of endemic regions, but also changes in the distribution of risk areas, including the identification of new, epidemically significant foci. In accordance with the risk-oriented approach to prophylaxis, forecasting of epidemic situation on tick-borne rickettsioses was given and differentiation of the endemic territories of the Russian Federation as regards Siberian tick-borne typhus was carried out with distinguishing of epidemiological zones of low, medium, above average, high and very high risk of population infection.

During 2000–2022, a total of 69 of Russia’s 85 administrative regions reported 164,580 hemorrhagic fever with renal syndrome (HFRS) cases, with an annual average rate of 4.9 cases/100,000 population (105 popul.). European Russia reported 162,045 (98.5%) cases in 53/60 regions with 9.7 cases/105 popul. Asian Russia reported 2535 (1.5%) cases in 16/25 regions with 0.6 cases/105 popul. In the same period, Russia reported 668 (0.4%) fatal HFRS cases, and 4030 (2.4%) cases among children under the age of 14 years. Most HFRS cases occurred during autumn and winter. The incidence among rural residents was 6.7 per 105 popul., higher than the urban 4.4 per 105 popul.; however, among HFRS patients, rural and urban residents account for 35% and 65%, respectively. Six hantaviruses, causing HFRS of different clinical severity, were recognized as pathogens: Hantaan (HTNV) and Amur (AMUV) of Orthohantavirus hantanense species, Seoul (SEOV) of Orthohantavirus seoulense species, Puumala (PUUV) of Orthohantavirus puumalaense species, and Kurkino (KURV) and Sochi (SOCV) of Orthohantavirus dobravaense species, with the principal hosts Apodemus agrarius coreae, Apodemus peninsulae, Rattus norvegicus, Myodes glareolus, Apodemus agrarius agrarius, and Sylvaemus ponticus, respectively. It was found that 97.7% of HFRS cases are caused by PUUV, therefore, this virus plays the main role in the HFRS morbidity structure in Russia.

Objective of the study was to analyze the incidence of Siberian tick-borne typhus (STBT) in the Russian Federation between 2010 and 2019, Astrakhan spotted fever (ASF) and Mediterranean fever (MF) since official registration, and forecast the development of the epidemic process for endemic rickettsioses for 2020. Materials and methods. The analysis of the incidence of STBT, ASF and MF in the Russian Federation over the period of 2010–2019, 2013–2019 and 2014–2019, respectively, in relation to the results of zoological-entomological monitoring. Results and discussion. The average long-term incidence rate of STBT for 2010–2019 in the Russian Federation on the whole was 1.1 0 /0000 (DI95 1.05÷1.08) without trends towards change. The maximum relative incidence of STBT is typical for the Siberian Federal District (SFD) where the average long-term incidence rate for 2010–2019 amounted to 6.28 per 100 thousand of the population. In the second place is the Far Eastern Federal District (FEFD) – 5.17 0 /0000, in third – the Ural Federal District (UFD) – 0.1 0 /0000. When assessing the 10‑year dynamics of the relative incidence of STBT, we have revealed a significant tendency to increase in the FEFD, a tendency to stabilize in the SFD and a significant downward trend – in the UFD. A reliable increasing trend in STBT incidence was detected in the Altai Republic and in the Khabarovsk Territory. Major decline in STBT incidence was observed in the Trans-Baikal territory, Krasnoyarsk territory, Kurgan Region and the Republic of Khakassia. There is a marked tendency to increase in the incidence of MF in the Republic of Crimea. In the Astrakhan Region and the Republic of Kalmykia, there is an expressed tendency towards the reduction in the ASF morbidity rates.

The review provides concise information on the innate ability of cells of the tularemia pathogen, Francisella tularensis subsp. Holarctica, to resist antimicrobials through a variety of mechanisms, leading to its multi-resistance. In total, taking into account new territories, 120 cases of human infection were registered in the Russian Federation in 2022. Epizootic manifestations of the infection of varying degrees of intensity were detected in 58 constituent entities. Against this background, sporadic cases of tularemia in humans were reported in 18 regions of the country. An outbreak of tularemia occurred in the Stavropol Territory; the disease of mild and moderate severity was found in 76 people. The increased incidence of tularemia persists in the Republic of Karelia with severe cases of the disease in the absence of immunoprophylaxis of this infection in the region. A total of 61 cultures of the tularemia pathogen F. tularensis subsp. holarctica, out of which 20 erythromycin-resistant strains were isolated in the Stavropol Territory. In addition, 8 cultures of F. tularensis subsp. mediasiatica from a silt sample and mites Dermacentor silvarum and Haemaphysalis concinna caught in the Republic of Altai were isolated. On the territory of the Russian Federation in 2022, 930 999 people were vaccinated and revaccinated against tularemia. Based on the analysis of the data obtained in 2022, epidemic complications in 2023 in the form of sporadic cases of the disease among the unvaccinated population are most likely to occur in the territories of the Central Federal District – in the Vladimir, Ryazan and Smolensk Regions; Northwestern Federal District – in the Arkhangelsk Region and the Republic of Karelia; Southern Federal District – in the Volgograd and Rostov Regions. The situation in the North Caucasian Federal District will remain tense in the Stavropol Territory; in the Volga Federal District – in the territories of the Saratov Region, as well as in the Kirov Region and the Republic of Mordovia; Ural Federal District – in Khanty-Mansi and Yamalo-Nenets Autonomous Districts; Siberian Federal District – in certain territories of Omsk, Kemerovo, Tomsk, Novosibirsk, Irkutsk Regions, Altai, Krasnoyarsk Territories; in the Far Eastern Federal District, the most intense epizootic activity of natural tularemia foci is in Primorsky Krai.

The aim of the review was to characterize the epidemiological situation on rickettsiosis of the tick-borne spotted fever (TSF) group in the constituent entities of the Russian Federation in 2012–2021 and provide a long-term forecast for 2022–2026. In 2020–2021, indicators of registered incidence of tick-borne rickettsiosis in Russia on the whole decreased relative to the average long-term pre-pandemic level in 2012–2019 by 2 fold for all forms of the TSF group on average (Siberian tick-borne typhus – STT, Astrakhan spotted fever and Mediterranean fever). A comparative analysis of the territories revealed a correlation between the incidence of STT and the number of medical facility visits due to “tick bites” (r=0.67, p=0.015), which, against the background of an increase in the frequency of contacts of the population with vectors in 2020–2021 in most regions and a decrease in the incidence in the same regions indicates the credible nature of the changes. The ranking of territories according to average long-term incidence rates made it possible to classify the Republic of Altai and the Altai Territory as regions of extremely high epidemic hazard as regards STT; high hazard – the Republic of Tuva; above average – the Republic of Khakassia, Khabarovsk Territory and the Jewish Autonomous Region. The established downward trend in the incidence of tick-borne rickettsiosis among the population will be sustained in most entities of the Russian Federation within the next 5 years, excluding the Republic of Altai, the Altai Territory, the Republic of Crimea and the city of Sevastopol, where current incidence or an increase should be expected. The results of the analysis indicate the need to put more emphasis on natural-focal infections at the time of COVID-19 pandemic.