Collecting of hard ticks by a flag from vegetation in Askold Island (Primorsky Territory) in May 17, 2023 has revealed the following 3 species: Haemaphysalis longicornis Neumann, 1901 (809 specimens), Haemaphysalis japonica douglasi Nuttall et Warburton, 1915 (223), Ixodes persulcatus Schulze, 1930 (4). A total of 1036 tick specimens were collected. The territory of the western part of the island was surveyed: a broad-leaved maple forest (925 ticks were collected) and a large-grass meadow (111). Identification of tick species was carried out according to morphological characters. The hard tick fauna of Askold Island is characterized by: 1) the dominance of H. longicornis, which is absent on neighboring islands; 2) a high proportion of nymphs in May among representatives of the genus Haemaphysalis (H. longicornis 96.0%, H. japonica 25.1%), the peak abundance of which is common in July–August; 3) a high abundance of ticks (more than 90.0 individuals per flag-hour; 4) absence of males in H. longicornis (32 females were collected). PCR did not detect infection of 160 nymphs (pools of 20 individuals) H. longicornis with markers of nucleic acids of tick-borne encephalitis virus, borrelia, anaplasma, ehrlichia and West Nile fever. However, since representatives of the genus Haemaphysalis are known as carriers of many other pathogens, the high abundance of hard ticks and the incompleteness of data on their infection rate do not allow us to classify the territory of Askold Island as an epidemiologically low-risk territory.

The aim of the work was to compare the main socio-demographic and eco-epidemiological parameters of tick-borne viral encephalitis, tick-borne borrelioses and tick-borne rickettsiosis.Materials and methods. The authors’ databases based on epidemiological investigation records were used for the study. All in all, 2974 cases (Irkutsk and the Irkutsk district) were analyzed during the periods of 1995–2022 for tick-borne viral encephalitis and tick-borne borrelioses, and 2001–2022 for tick-borne rickettsiosis.Results and discussion. The following parameters were assessed: the timing of epidemic season; the geography of prevalence; localization of tick bite on the human body; incubation time; gender and age structure of patients; social composition and exposure conditions. It was shown, that the parameters had their own features for each disease, and part of them are common to all Eurasian area of these infections. The shared characteristics include: the early epidemic season onset for tick-borne rickettsiosis; the shorter incubation time for tickborne rickettsiosis as compared to tick-borne viral encephalitis and tick-borne borrelioses; the increased frequency of tick-borne rickettsiosis vectors’ bites near the head and neck, and tick-borne borrelioses vectors – on the torso; large percentage of older persons among patients with tick-borne borrelioses and children under 14 years of age among patients with tick-borne rickettsiosis; prevalence of male population over female one as regards all surveyed pathogens. Low incidence of tick-borne diseases among professional contingent (the work associated with staying in natural foci of infection), an increased risk of tick-borne encephalitis and rickettsiosis among social group “unemployed”, and tick-borne borrelioses – among retirees, can be attributed to regional specificity.

The aim of the review was to conduct a comparative analysis of the epidemiological situation on tick-borne encephalitis (TBE) over 2014–2023 in the constituent entities of the Russian Federation located in the European and Asian parts of the country and to give a forecast of incidence for 2024. The incidence of TBE in 2023 only marginally decreased as compared to the peak values in 2022, which leveled down the ten-year trend towards reduction. Grouping of the entities of the Russian Federation according to the average incidence of TBE over a decade made it possible to classify 17 of them as regions of low, 15 – of medium, and 17 – of high epidemiological risk. In general, the epidemiological situation regarding TBE is more unfavorable in the Asian part of the country. A list of species of Ixodidae ticks, the main vectors of the tick-borne encephalitis virus, is provided, as well as subtypes and genetic variants of the latter, identified in the European and Asian parts of the country. The peculiarities of the epidemiological situation on TBE and the scope of preventive measures undertaken in Russia in 2023 are considered. It is shown that there are no clearly outlined trends in the nature of changes in the incidence of TBE in endemic federal districts and entities of the country, and the expected incidence rates in 2024 will remain at the long-term average level.

The aim of the study was to analyze the genetic structure of populations and the patterns of evolutionary variability of the novel coronavirus infection in the Siberian and Far Eastern Federal Districts. Materials and methods. 1033 SARS-CoV-2 genomes from samples from individuals diagnosed with COVID-19 from eight entities of the Siberia and Far East between December 2020 and November 2021 were assessed. Sequencing was performed on the MinION Oxford Nanopore platform using the ARTIC v.3 protocol. The degree of SARS-CoV-2 genetic isolation was estimated applying the Fst criterion. Phylogenetic analysis was carried out using maximum likelihood method and Bayesian phylogenetic inference. A nonparametric Bayesian Skyline Plot (BSP) model was used to reconstruct population dynamics. Results and discussion. The original SARS-CoV-2 variant (B.1) was identified in 100 % of the cases at the initial stages. The Alpha variant was detected in March-June, 2021; Beta – in single samples in March-May, 2021. Delta was first identified in April, 2021. The maximum degree of SARS-CoV-2 genetic isolation (Fst=0.18) was established for the most remote territories (Altai Territory ↔ Republic of Buryatia and Altai Territory ↔ Irkutsk Region). A relatively free circulation of the virus was detected between Irkutsk Region, Republic of Buryatia and Krasnoyarsk Territory. According to the results of population genetic tests, a sharp increase in the effective virus population size was the determining mechanism of SARS-CoV-2 genetic diversity formation. Reconstruction of population dynamics in BEAST (BSP model) has revealed the consistency of trends in the genetic diversity of the virus and the number of active cases. Two subclusters have been identified in the Delta cluster, consisting predominantly of samples isolated in the Irkutsk Region and Krasnoyarsk Territory. Change in the dominant variant of SARS-CoV-2 has been traced in dynamics. Molecular-epidemiological data point to the multiple pathways of spatial expansion of different SARS-CoV-2 genotypes into the constituent entities with generation of individual monophyletic clusters and further intra- and extraterritorial spread of the decedents.

The aim of this work was to analyze the spatial and temporal features of the epidemic process dynamics of tick-borne encephalitis (TBE) in Irkutsk Region in 2001–2021. Materials and methods. The data of the Rospotrebnadzor Administration for the Irkutsk Region, the Reference Center of the Irkutsk Research Anti-Plague Institute, the materials of the state statistical reporting form No. 2 “Information on infectious and parasitic diseases”, and scientific publications were analyzed. The chronological and chorological features of the change in the incidence of TVE have been traced. In the latter case, the administrative-territorial formations (ATF) of the subject were differentiated by epidemiological risk groups over two ten-year periods: 2001–2010 and 2011–2020. At each time interval, the grouping of areas according to the level of TBE incidence was carried out using the calculation of 95% confidence interval. Time sequences of observations were analyzed using the construction of regression equations. Standard methods of variation statistics in the Microsoft Excel were deployed. Results and discussion. Over the course of the 21st century, the incidence of TBE in Irkutsk Region has been declining. Based on 2001–2010 data, there were no cases of TBE in six ATF, and endemic areas were divided into three groups: with low (15 districts), medium (6) and high (8) incidence of TBE. A separate assessment of morbidity rates was conducted in the administrative center of the entity, the city of Irkutsk. In 2011–2020, the structure of ATF with varying epidemiological risk of TBE underwent a change. Six non-endemic areas, groups of low (12 ATFs), medium (9), high (6) and very high (2) epidemiological risk were identified. The spatial arrangement of high epidemiological risk zones changed, and their area increased. Each ATF cluster with different TBE incidence in 2011–2020 is characterized by the number of TBE cases and the volume of measures to prevent the infection. It is concluded that preventive measures were insufficient in ATF groups of high and very high epidemiological risk.

During epizootological examination of Popov Island (Primorskii Territory) in May 23–25, 2022, a total of 651 specimens of 4 species of ixodid ticks were collected off vegetation: Ixodes pavlovskyi pavlovskyi Pomerantzev, 1946 (77.5

The results of long-term monitoring of the taiga ticke I. persulcatus abundance and its infection rate with tick-borne encephalitis virus and bacteria of genus Anaplasma, Borrelia, Ehrlichia and Rickettsia in forests along the Baikalian highway (road No 25К-011 Irkutsk region, Russia). The ticks’ abundance varied in space and time from complete lack on the registration route up to 339 ticks per flag-hour. The dynamics during study period (2005-2022) had three waves of ups and downs. The maximum of long-term average seasonal activity occurred at second and third decade of May. The average numbers of ticks increased as distance from the city grew. The analysis with the help of multiplex test system for four infections (tick-borne encephalitis virus, Anaplasma, Borrelia, Ehrlichia) showed marker at least of one pathogen in 57 % of specimens, different mixes of two and more co-infections – in 16.3 %. From 10 variants of co-infections found in this sample, the most prevalent were combinations of Borrelia, Ehrlichia and Anaplasma (74.7 % of double and 7.5 % triple «mixes»). Least often, the ticks were co-infected with tick-borne encephalitis virus in combination with Ehrlichia and Anaplasma (0.5 % each). In average the ticks most often contained the genetic material of Rickettsia (68.1±2.94 % of tested samples) and Borrelia, (48.3±1.30 %), then, in descending order, – Anaplasma, (13.5±0.88 %), Ehrlichia (9.5±0.76 %) and tick-borne encephalitis virus (3.0±0.47 %). Despite the low proportion of ticks with the virus in natural foci, 68.5 % of the persons, bit by infected ticks on the territories along Baikalian highway, became ill with tick-borne encephalitis. Conversely, with a wide prevalence of Rickettsia and Borrelia in ticks, the tick-borne rickettsiosis was diagnosed in 3.1 % of the victims and borrelioses – in 28.4 %. No significant differences have been revealed between the infection rate of adult ticks and nymphs, and between males and females, except for Borrelia, which more often have been found in females than in males (51.9 % versus 45.7 %). The tendencies of the pathogens prevalence in time and different plots of territory studied and risks for human infection have been revealed. It was shown than more than a half of human tick-borne encephalitis, tick-borne borrelioses and tick-borne rickettsiosis contracting occurs in the closest suburbs of Irkutsk – up to the 30th km of the highway, where the ticks’ abundance is lower, than in more distant areas, in other words are more to do with human behavioral factor than with the vector’s activity.

Until 2020, there were only three original complete genome (CG) nucleotide sequences of Omsk hemorrhagic fever virus (OHFV) in GenBank. For this reason, the evolutionary rate and divergence time assessments reported in the literature were based on the E gene sequences, but notably without temporal signal evaluation, such that their reliability is unclear. As of July 2022, 47 OHFV CG sequences have been published, which enables testing of temporal signal in the data and inferring unbiased and reliable substitution rate and divergence time values. Regression analysis in the TempEst software demonstrated a stronger clocklike behavior in OHFV samples for the complete open reading frame (ORF) data set (R2 = 0.42) than for the E gene data set (R2 = 0.11). Bayesian evaluation of temporal signal indicated very strong evidence, with a log Bayes factor of more than 5, in favor of temporal signal in all data sets. Our results based on the complete ORF sequences showed a more precise OHFV substitution rate (95% highest posterior density (HPD) interval, 9.1 × 10−5–1.8 × 10−4 substitutions per site per year) and tree root height (416–896 years ago) compared with previous assessments. The rate obtained is significantly higher than tick-borne encephalitis virus by at least 3.8-fold. The phylogenetic analysis and past population dynamics reconstruction revealed the declining trend of OHFV genetic diversity, but there was phylogenomic evidence that implicit virus subpopulations evolved locally and underwent an exponential growth phase.

Background: A descriptive epidemiological study of the rabies outbreak in the Amur Region of Russia (ARR), which remained rabies-free from 1972 to 2017, was carried out. During 2018-2022, 49 animal rabies cases and one human rabies death were documented in the ARR. This study aimed to detect possible ways of incursion and features of the spatial spread of rabies virus (RABV) in ARR, which was considered rabies-free for 45 years. Methods: After the beginning of the outbreak, 1,450 animal brain samples were tested using a direct fluorescent antibody test. Genetic analysis of RABV isolates was carried out (n = 9). GIS was used to analyze the spatial spread of rabies in ARR and adjacent territories. Results: Rabies has been confirmed in red foxes (Vulpes vulpes ) - 38.8%, raccoon dogs (Nyctereutes procyonoides ) - 10.2%, wolves (Canis lupus ) - 14.3%, dogs - 18.4% and farm animals - 18.3% (n = 49). The first cases were detected south of the ARR, 30 km from the state border between Russia and China. In 2018-2022, the RABV spread within the forest-steppe landscapes of the Zeya-Bureya Plain northwesterly; the maximum distance from the first recorded event was 192.4 km (Me = 77.6). According to a phylogenetic analysis, the isolates from ARR belonged to the Acrtic-like-2 RABV lineage and showed the maximum similarity to the isolates recovered in the province of Heilongjiang (China, 2011, 2018) and the Jewish Autonomous Region (Russia, 1980). Conclusion: Rabies was most likely introduced by wild carnivores from the adjacent territories of Russia or China, located downstream of the Amur River.

In 2022, there was an increase in the incidence of tick-borne encephalitis (TBE) and ixodid tick-borne borreliosis (ITBB) in the subjects of the Russian Federation, federal districts and the country as a whole. At the same time, among people affected by ixodid ticks, the proportion of clinical forms of the diseases has increased. The aim of this study is to analyze the possible causes of the simultaneous increase in the incidence of vector-borne infections and the proportion of clinical forms among the people bitten by the ticks, using the materials on Krasnoyarsk Territory as an example. Materials and methods. We analyzed the incidence of TBE and ITBB among the people who have or haven’t had COVID‑19, the number of people affected by tick bites in 2021–2022 in Krasnoyarsk Territory. Statistical analysis is performed by standard methods of variational statistics using Excel. Results and discussion . It is shown that in the Krasnoyarsk Territory, with a decrease in the number of individuals affected by tick bites in 2022 as compared to 2021 (12216 and 13214, respectively), there was an increase in the number of cases of TBE (from 124 to 250) and ITBB (from 115 to 224), as well as the proportion of people who had clinical forms of the infections after tick bites. Among three possible explanations of the observed pattern, a decrease in the immune status of Krasnoyarsk residents who had had COVID‑19 before the contact with ticks is considered as the most likely one. Using statistical methods it was substantiated that among people with TBE and ITBB, the proportion of individuals who have had COVID‑19 is significantly higher than expected, based on the actual incidence of the Krasnoyarsk Territory population with a new coronavirus infection. Thus, COVID‑19 affects the incidence of vector-borne infections indirectly, through a change in the number of people contacts with natural stations, and directly, by changing the immune status.

The aim of this review is to predict the incidence of tick-borne viral encephalitis (TBVE) in the Russian Federation for 2023 based on analysis of the epidemiological situation on TBVE during 2012–2022. Over the decade, the highest incidence of TBVE was registered in the Siberian, Volga and Ural Federal Districts. In 2022, the Ural Federal District took the second place, the share of the North-Western one decreased by almost two times. Ranking of territories according to the rate of TBVE incidence at the level of constituent entities has made it possible to attribute 16 of them to the group of regions with a high epidemic risk, 14 – to medium epidemic risk, and 18 – to a low epidemic risk. In 2022, the incidence of TBVE in Russia increased by 1.9 times compared to 2021, and amounted to 1.34 0 / 0000 . Despite the increase in the incidence of TBVE in 2022, a significant downward trend has been retained. The rate of infection of ticks removed from humans in 2022 was below the long-term average values. PCR and ELISA were applied for tests. Infection rate of ticks from environmental objects when studied by PCR was higher than the multi-year average values, and lower when studied by ELISA. In 2022, 3.5 million people were immunized against TBVE (vaccinated and revaccinated). Emergency immunoprophylaxis with immunoglobulin covered 24.5 % of the people affected by tick bites (children accounted for 34.3 %). The forecast for TBVE incidence in Russia in 2023 remains favorable. It is expected to be reduced to (0.83±0.298) 0 / 0000 . However, there was not only an increase in the number of TBVE cases, but also the proportion of clinical manifestations of the disease, as well as lethal outcomes among those who suffered from tick bites in 2022. If this pattern holds, the incidence of TBVE in 2023 will be higher than predicted, especially in the constituent entities where the share of individuals with manifest forms among those who suffered from tick bites has increased greatly.

The state of the natural foci of tick-borne encephalitis (TBE) was monitored during 15 seasons (2005–2019) in several key plots within a popular recreational and tourism area along Highway 25K-011 Irkutsk–Baikal. The populations of the virus and its main vector, the taiga tick Ixodes persulcatus , were shown to be in a stable state. The studied plots varied strongly in the density of adult ticks and in its multi-year and seasonal dynamics. Spatial and temporal variations in the tick infection rate were detected, but no specific trend over the study period was observed. The multi-year density dynamics of the vector did not correlate with that of its infection rate. A significant role of the taiga tick males in dissemination of the TBE virus has been highlighted.

Aim. To study the trends and to assess longterm incidence of ixodid tick-borne borreliosis (ITB) and Siberian tick typhus (STT) in Eastern Transbaikalia for the improvement of preventive measures. Materials and Methods. We carried out a retrospective analysis of ITB and STT incidence in different districts of the Eastern Transbaikalia during 2003–2021. Epidemic trends were characterised using linear regression equations. Results. Average annual incidence of ITB in 2003–2021 was 4 cases per 100,000 population. Analysis of two periods (2003–2012 and 2013– 2021) showed an increase in ITB incidence in 2013–2021 (5.1 ± 0.79 per 100,000 population) as compared to 2003–2012 (2.6 ± 0.73 per 100,000 population, p < 0.05). Within 2013–2021 period, there has been a statistically insignificant trend towards decreasing ITB incidence. The incidence of STT was lower than that of ITB and there was no statistically significant trend towards change of this scenario (average annual incidence in 2003– 2021 was 2.1 ± 0.37 per 100,000 population). Between 2012 and 2021, in particular before 2017, the incidence of STT reduced (average annual incidence in 2012–2021 was 1.5 ± 0.43 per 100,000 population). The epidemiological risk of ITB and STT varied across the distinct territories of Eastern Transbaikalia. Conclusion. In order to prevent the incidence of tick-borne diseases, acaricide treatments should be regularly carried out. Amounts of such interventions should be determined depending on the risk of human infection.

The aim of the work was to analyze the epidemiological situation on tick-borne viral encephalitis in the endemic territories of the Russian Federation in 2021 in comparison with the dynamics over 2011–2020 and its shortterm forecast for 2022. In Russia, 48 constituent entities belonging to seven federal districts are endemic for tick-borne viral encephalitis (TBVE). There is a statistically significant downward trend in the incidence of TBVE in the Siberian Federal District (which is characterized by the maximum incidence rate in the country), the Volga and Far Eastern Federal Districts. In the Ural Federal District (the second in terms of TBVE incidence), the decline in the incidence has stalled since 2021. The average long-term incidence of TBVE in the constituent entities of the Russian Federation varies from sporadic (Republic of Crimea) up to 12.5 per 100 thousand of the population ( 0 / 0000 ) (Krasnoyarsk Territory). In 2021, TBVE cases were detected in 42 endemic regions and in one non-endemic region – Stavropol Territory. At the same time, 1015 cases of TBVE were in the country (0.69 0 / 0000 ). In all Federal Districts, the incidence of TBVE is below the long-term average values. Using the Quantum GIS program, the incidence of TBVE in 917 administrative territories of the country has been ranked and grouped according to the level of epidemiological risk. This made it possible to establish that 65 % of the territories form a zone of low epidemiological risk. High and very high epidemiological risk is observed in 13% of the analyzed districts. The structure of TBVE clinical manifestations in 2021 was dominated by febrile (59.7 %) and meningeal (24.3 %) forms. 14 lethal outcomes were reported. In 2021, 2 889 515 people were vaccinated (including 1 433 850 children), of which 14 fell ill. Specific immunoglobulin was used to prevent the overt development of infection in 100 704 individuals, which accounts for 22.6 % of the persons affected by tick bites (30.6 % among children). Acaricidic treatments were carried out on an operational area of 233 125 hectares of territories of socially significant objects. The scope of all TBVE prevention measures in 2021 increased as compared to 2020. In 2022, a decline in the incidence of TBVE in endemic Federal Districts and in the country on the whole is forecasted to (0,64±0,192) 0 / 0000 .

Tick-borne viral encephalitis (TBVE) is one of the most significant natural-focal infections in the Russian Federation.The aim of the study was to analyze the current epidemiological situation on TBVE in the Buryat Republic in 2010–2020 with a subsequent differentiation of municipalities by epidemiological risk groups in order to elaborate proposals for optimization of preventive measures.Materials and methods. A retrospective analysis of the epidemiological situation on TBVE in the Buryat Republic was carried out using forms of federal statistical surveillance No. 2 “Information on infectious and parasitic diseases” over 2010–2020 and the data from the Reference Center of the Irkutsk Research Anti-Plague Institute of Siberia and Far East of the Rospotrebnadzor on the epidemiological situation and preventive measures in the municipalities of the constituent entity. Statistical processing was performed applying conventional methods of variation statistics. Based on calculated 95 % parametric confidence interval for the data on variability of the long-term average TBVE incidence in the municipalities of the Republic of Buryatia over a 10-year period, the entities were differentiated by epidemiological risk groups. QGis 2.18.28 and a set of open geodata OpenStreetMap were used for mapping.Results and discussion. All municipalities have been classified into five groups by the level of epidemiological risk: with zero TBVE incidence – 2 districts, with a low level – 4, medium – 8, high – 5, very high – 2. In addition, the administrative center has been placed into a separate group. Each individual group of municipalities is characterized by the number of TBVE cases, the level of morbidity, the frequency of seeking medical aid because of tick bites, the scope of specific and non-specific prevention measures. Recommendations for optimizing the tactics of TBVE prevention in certain municipal districts have been provided.

The tick-borne flavivirus (TBFV) group contains at least 12 members where five of them are important pathogens of humans inducing diseases with varying severity (from mild fever forms to acute encephalitis). The taxonomy structure of TBFV is not fully clarified at present. In particular, there is a number of paraphyletic issues of tick-borne encephalitis virus (TBEV) and louping-ill virus (LIV). In this study, we aimed to apply different bioinformatic approaches to analyze all available complete genome amino acid sequences to delineate TBFV members at the species level. Results showed that the European subtype of TBEV (TBEV-E) is a distinct species unit. LIV, in turn, should be separated into two species. Additional analysis of the diversity of TBEV and LIV antigenic determinants also demonstrate that TBEV-E and LIV are significantly different from other TBEV subtypes. The analysis of available literature provided data on other virus phenotypic particularities that supported our hypothesis. So, within the TBEV+LIV paraphyletic group, we offer to assign four species to get a more accurate understanding of the TBFV interspecies structure according to the modern monophyletic conception.

INTRODUCTION:Tick-borne encephalitis virus (TBEV) is medically most important representative of the same-name serogroup of genus Flavivirus (Flaviviridae). In the view of various researchers there are 3 to 5 TBEV subtypes, of them siberian being the most prevalent. The aim of the work is to compare the biological properties and to reveal phylogenetic relationships of large group of modern (2006-2019) TBEV isolates of siberian subtype from natural foci in southern East Siberia.MATERIAL AND METHODS:Ixodid ticks (Ixodidae) and small mammals (Mammalia) from tick-borne encephalitis (TBE) natural foci in Irkutsk Region, Republic of Buryatia and Republic of Tuva, as well as specimens from TBE patients, were examined for TBEV markers using enzyme-linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction (RT-PCR). Virus was isolated from suspensions with positive result, and its pathogenicity for white mice (Mus) (WM) was studied by different inoculation ways. Analysis of the nucleotide sequences of E gene was performed for isolates at 1st passage. Phylogenetic tree was constructed using MEGA X program.RESULTS:The phylogenetic analysis has shown that TBEV of siberian subtype that circulates in natural foci of the studied territory belong to two genetic lines. These lines are «Vasilchenko» and «Zausaev» with a strong predominance of the first. The differences in biological properties between the two groups of strains have been demonstrated. Most of the strains from both groups showed high virulence for WM both after intracerebral and subcutaneous inoculation. Only four strains demonstrated the reduced ability to overcome the blood-brain barrier. However, the analysis of the E protein coding sequences revealed evident correlation between phylogenetic clustering and geographical origin of isolates, but not with TBE host or pathogenicity for WM.CONCLUSION:Further search for TBE genome regions associated with pathogenicity require the analysis of complete genome sequences of representative group of strains with different biological properties.

Relevance. Severe fever with thrombocytopenia syndrome is a viral disease characterized by acute fever, accompanied by progressive thrombocytopenia, leucopenia. The mortality is up to 30%. The disease was first identified in 2009 in rural areas of central China, Hubei and Henan. The causative agent of the disease is a new Severe Fever with Thrombocytopenia Syndrome Virus (SFTSV). The SFTSV is mainly transmitted through tick bites, especially Haemaphysalis longicornis which is the dominant tick species in East Asia.The aim of the review is to analyze relevant information about Severe Fever with Thrombocytopenia Syndrome, including the molecular genetics features of the pathogen, clinical manifestations, geographical distribution, epidemiological features, as well as the possibility of drift and spread of infection in the Russian Federation.Conclusions. SFTS is a serious health threat as it relates to new and re-emerging infections. The further spread of SFTS in China may complicate the epidemiological situation in the country. SFTSV may have a much wider global distribution in Southeast Asia than is currently known. The risk of H. longicornis ticks spreading is predicted in the north-east United States, New Zealand, parts of Australia and several Pacific islands. The presence of the H. longicornis in the Primorsky Territory on the Far East indicates a possible risk of the natural focus formation in the event of the introduction of the pathogen.

In summer 2019 in western Irkutsk region abundant and long rainfall caused a catastrophic flood that became a federal emergency. It resulted in a threat that natural infection foci would be activated in that emergency zone; given that, the Irkutsk Anti-plague Institute, together with Rospotrebnadzor territorial offices and regional veterinary authorities, conducted an epizootologic-epidemiologic study on affected territories in order to detect and predict possible epidemiologic risks. Totally, the study covered 30 socially significant objects and natural biotopes in three mu-nicipal districts in the region. We tested blood serum of people (244 samples), farm and home ani-mals (253), and organs taken from caught small mammals aiming at determining natural foci infec-tions in them with bacteriologic, serologic, and PCR procedures; overall. 4,370 examinations were performed. Share of immune people amounted to 13.1% regarding tularemia; 17.5%, tick-borne en-cephalitis; yersiniosis, 10.8%; leptospirosis, 3.1%; tick-borne borreliosis, 7.1%. Antibodies to pathogenic leptospira were detected in 36.0–81.3% farm animals and it can indicate there is a latent epizootic process. In July 2019 there was low population of synanthropic rodents in socially significant objects on affected territories and small mammals population also decreased in natural foci with high contagion rate for tularemia agent (down to 17.9%). In September 2019 rats were detected to inhabit food-related objects and small mammals migrated actively in natural stations, contagion rate with tularemia agent going down among them whereas there was a growth in conta-gion rate with leptospira (up to 40.0%). We also revealed new natural tularemia and leptospirosis foci. Activity in natural infections foci didn’t exceed long-term average level just after the flood; still, there are persisting risks on affected territories in Irkutsk region that an epidemiologic situation might get worse there. The paper contains recommendations on further epizootologic-epidemiologic monitoring and organizing prevention activities such as control over sanitary situation at socially significant objects, local deratization, and sanitation in natural foci of animal leptospirosis.