Anna P Khametova

Epizootiological-epidemiological situation on tularemia in the Russian Federation in 2025 has been assessed and forecast for 2026 is provided. In 2025, 45 cases of human tularemia were registered in the Russian Federation (incidence rate of 0.03 per 100,000 population) across 16 regions of the country. The highest proportion of cases was recorded in the Stavropol Territory and the Khanty-Mansi Autonomous Region (21.6 and 16.2 %, respectively). Arkhangelsk Region and Republic of Karelia accounted for 10.8% each, the Kirov, Omsk and Chelyabinsk Regions – 8.1% each, Voronezh, Yaroslavl, Nizhny Novgorod Regions and the Krasnodar Territory – 2.7% each. The main share (48.9%) of all cases occurred in August and September. The urban population predominated in the morbidity structure – 62.2%. The incidence was characterized by a relatively even distribution by gender: men accounted for 55.6%, women – 44.4%. The largest share of the affected was among people of working age, but noteworthy is the significant proportion of sick children under 17 years of age – 24.5%. Ulceroglandular tularemia (A21.0) predominated, accounting for 71.1% of cases. A total of 871,599 people were vaccinated or revaccinated against tularemia. Nationwide, 28 cultures of Francisella tularensis were isolated from field material in 7 entities. High risk of epidemiological complications due to tularemia will persist in 20 regions of the Russian Federation: Arkhangelsk, Leningrad, Volgograd, Kirov, Novosibirsk, Omsk, Tomsk, Kherson and Zaporozhe Regions; the Republics of Karelia, Crimea, Mordovia, Tuva, Buryatia and Sakha (Yakutia); Stavropol and Altai Territories; Khanty-Mansi Autonomous Region; and the Donetsk and Luhansk People’s Republics.

The aim of the study was to evaluate the involvement of the small white-toothed shrew, Crocidura suaveolens , in the circulation of pathogens of natural-focal infections: tularemia, Lyme borreliosis (LB), Crimean-Congo hemorrhagic fever (CCHF), and hemorrhagic fever with renal syndrome (HFRS) in the southern part of the East European Plain in the Rostov Region (RR). Materials and methods. The findings of the epizootiological monitoring of natural-focal infections in the Rostov Region in 2019–2024 were used for the analysis. 280 specimens were caught during the specified period; 108 samples were formed, which were examined using bacteriological, molecular-genetic and immunological methods. Results and discussion. It has been found that over the past five years, the index of dominance of the small white-toothed shrew in captures has changed from a minimum (0.86 %) in 2021 to a maximum (12.10%) in 2024. It is established that the proportion of positive samples of small white-toothed shrew infected with tularemia pathogens, LB, CCHF and HFRS viruses differs in catches. During the observation period, the highest infection rate of the small white-toothed shrew was noted in regard to tularemia – 8 (7.4±2.5%) and CCHF – 6 (5.6±2.2%), the lowest – to LB – 4pathogens (3.7±1.8%) and HFRS – 3 (2.8±1.6%). According to the cartographic analysis, the administrative districts, where positive findings were identified, are located in the southwestern part of the RR (Rodionovo-Nesvetaisky, Matveevo-Kurgansky, Neklinovsky, Azovsky districts), in the northwestern part (Millerovsky district), and in the southeast (Remontnensky district). The research has showed the need for further study of significance of the small white-toothed shrew species for the circulation of pathogens of natural-focal infections as a species with high phenotypic adaptability.

The aim of the work was to assess the state of natural foci of tularemia, Ixodidae tick-borne borrelioses (ITBB), West Nile fever (WNF), Crimean hemorrhagic fever (CHF) and hemorrhagic fever with renal syndrome (HFRS) in the territories of the Rostov Region, Donetsk and Lugansk People’s Republics as of 2023. Materials and methods . The study of field material samples, which included 2782 specimens of Ixodidae ticks of six species, 9874 specimens of blood-sucking mosquitoes of 12 species and 2974 specimens of small mammals of 17 species, collected in 2023 in the territories of the Rostov Region, Donetsk and Lugansk People’s Republics, was carried out for the presence of markers of CCHF, WNV, HFRS, Lyme disease, tularemia and leptospirosis pathogens. Infectious agents were indicated using bacteriological, serological and molecular-genetic methods. Results and discussion . Five tularemia cultures were isolated in the Rostov Region and the presence of tularemia pathogen markers was confirmed (11 positive PCR samples and 15 positive antigen tests), as well as ITBB (12 positive PCR tests), WNF (one positive PCR test and two positive ELISA tests), and CCHF (10 positive PCR tests and five positive ELISA tests). In the Donetsk People’s Republic, markers of tularemia pathogens (six pure cultures, one positive PCR test, and 50 positive antigen tests), ITBB (93 positive PCR tests), leptospirosis (one positive PCR test), WNF (one positive ELISA test), CHF (one positive PCR test and two positive ELISA tests), and HFRS (eight positive ELISA tests) were registered. Markers of tularemia pathogens (one pure culture, 14 positive PCR samples and 49 positive antigen tests), ITBB (65 positive PCR samples), leptospirosis (one positive PCR sample) and HFRS (12 positive ELISA samples) were detected on the territory of the Lugansk People’s Republic. Thus, general structure of parasitic system of active natural foci of infectious diseases, functioning as part of integrated landscape-ecological complex, has been formed in the territory of the Rostov Region, Donetsk and Lugansk People’s Republics.

Ixodidae tick-borne borreliosis (ITBB) is the most common transmissible disease in the Northern Hemisphere. The study of the features of the biocenotic structure and functioning of natural foci of ITBB in the steppe and dry steppe zones is of particular interest. The territory of the Azov Lowland is a plain with a steppe type of landscape. In 2023–2024, on most of that area, employees of the Rostov-on-Don Anti-Plague Institute of the Rospotrebnadzor conducted epizootiological monitoring of natural focal infectious diseases, including ITBB. The aim of the work was to study the state and structure of the natural focus of ITBB in the steppe zone of the Azov Lowland. Materials and methods. The work used the results of the epizootiological survey. The study was carried out using epidemiological, zoological, genetic diagnostic and statistical methods. Results and discussion. It has been established that the main carriers of borreliosis pathogens in the ITBB natural focus of the Azov Lowland are small mammals: house mouse, European wood mouse, small wood mouse, yellow-necked mouse, lesser white-toothed shrew and gray hamster. The main carriers are Ixodidae ticks, Ixodes redikorzevi and Ixodes ricinus. This ITBB focus is of anthropourgic nature and stays in an active state. It is characterized by a low level of potential danger of infection of people with borreliosis pathogens.

147 human tularemia cases were registered on the territory of the Russian Federation (the relative incidence rate per 100,000 population is 0.1) in 20 regions of the country in 2024. An unfavorable epidemic situation persists in the territories of the Republic of Karelia (50 tularemia cases); an increase in the incidence was recorded in the KhantyMansi Autonomous District – Yugra (58) and in the Sverdlovsk Region (12), which accounts for 81.6 % of all cases of tularemia in the country. 31 cultures of Francisella tularensis were identified in six regions of the Russian Federation. In 2024, 937,962 people were vaccinated and revaccinated against tularemia. In 2025, the high risk of epidemic complications of tularemia will remain in the Central Federal District (Ryazan, Orel and Bryansk Regions), the Southern Federal District (Volgograd, Rostov Regions and the Republic of Crimea), the North Caucasusian Federal District (Stavropol Region), the North-Western Federal District (Arkhangelsk Region, Republic of Karelia, Nenets Autonomous District), Ural Federal District (Sverdlovsk Region and Khanty-Mansiysk Autonomy, District Yugra), Siberian Federal District (Novosibirsk and Tomsk Regions, The Republic of Altai and Altai Territory), as well as in the Donetsk and Lugansk People’s Republics, Zaporozhe and Kherson Regions.

The aim of the study was to differentiate the territory of the Rostov Region according to the potential risk of infection of the population with pathogens of Ixodidae tick-borne borreliosis (ITBB). Materials and methods. The analysis of the epidemiological situation in 2012–2022 was carried out based on the materials provided by the Federal State Budgetary Health Institution “Center of Hygiene and Epidemiology in the Rostov Region” and the Rospotrebnadzor Administration in the Rostov Region. The basis of epizootiological studies was the data from the ITBB monitoring conducted by the employees of the zoological-parasitological team from the Department of Epidemiology of the “Rostov-on-Don Anti-Plague Institute of the Rospotrebnadzor” in 2015–2022 and provided by the “Center of Hygiene and Epidemiology in the Rostov Region” and the “North-Caucasian Plague Control Station of the Rospotrebnadzor”. Conventional epidemiological, zoological and parasitological, gene diagnostics and analytical research methods were used for the work. Results and discussion. The territorial zoning of the Rostov Region has been carried out on the basis of the score-assessment system of the following factors: the magnitude of the epizootic potential, population density, and morbidity within the boundaries of administrative districts. The Rostov Region is a territory with the persistent natural ITBB focus, which has epizootic and epidemic manifestations. In order to improve epidemiological surveillance on ITBB, the territorial zoning of the region based on the risk-oriented approach has been conducted.

Филогенетическая характеристика штаммов возбудителя туляремии на территории Ростовской области и выявление эритромициночувствительных геновариантов.

An epizootological inspection of the liberated territories of the Donetsk and Lugansk People's Republics, Zaporozhye and Kherson regions was carried out. It was established that the faunal complex of small mammals, hare-like and ectoparasites, as well as their number, make it possible to ensure the circulation of natural focal infections identified by the results of laboratory studies: tularemia, Crimean hemorrhagic fever (CHF), West Nile fever (WNF), ixodic tick-borne borreliosis (ITB), rickettsiosis, human granulocytic anaplasmosis (HGA), leptospirosis, hemorrhagic fever with renal syndrome (HFRS), Q fever, intestinal yersiniosis, Batai, Inco, Sindbis, Tyaginya fevers. For the first time, the PCR method in field material from the Zaporozhye region (Berdyansk and Melitopol regions) detected the Crimean-Congo hemorrhagic fever virus, on the territory of the Donetsk and Lugansk People's Republics in the populations of small mammals (rodents and insectivores), the circulation of viruses Inco, Sindbis, Tyagin, Batai was established. In the territories of Kherson and Zaporozhye regions, the presence of combined and conjugated natural foci of ixodic tick-borne borreliosis, rickettsiosis and human granulocytic anaplasmosis is determined. According to the results of molecular genetic analysis, it was shown that the causative agents of natural focal infections (Crimean hemorrhagic fever, West Nile fever, ixodic tick-borne borreliosis, rickettsiosis) identified in 2023 are genetically close to strains circulating in the regions of the south European part of Russia.

Достижения в области изучения молекулярно-биологических характеристик различных видов рода Borrelia

The aim of study was to conduct epizootiological monitoring of natural tularemia foci of the steppe type and investigate epizootic activity in the south-east of the Rostov Region.Materials and methods. An epizootiological survey was carried out on the territory of Remontnensky, Sal’sky and Peschanokopsky districts of the Rostov Region in 2019–2021. To capture and collect mammals, Ixodidae ticks and to study the samples of field material conventional methods were used.Results and discussion. Habitation of 16 species of small mammals, 6 species of Ixodidae ticks has been found. Molecular-genetic analysis of the voles has revealed the presence of the species Microtus arvalis obscurus in the studied area of the region. The circulation of the tularemia agent has been established in the population of common and social voles, forest mouse, hare, rook, Dermacentor marginatus, Hyalomma marginatum, removed from rooks. In May 2020, a high increase in the number of the social vole in the Remontnensky district (up to 21 %), in July 2020 – the common vole in the agrocenoses of the Sal’sky district (up to 33 %) was observed. An extensive epizooty of tularemia was detected in the population of common vole in the south-east of the Rostov Region and in adjacent territories in the Republic of Kalmykia and the Stavropol territory. Two cultures of the pathogen were isolated from the fallen and captured social voles, and four cultures – from the common vole. The isolated strains belong to the Holarctic subspecies of Francisella tularensis EryR. The results obtained attest to the activation of the natural tularemia focus in the south-east of the Rostov Region and its high epizootic activity.