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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.

Background. To date, the genetic variability of Rickettsia helvetica has not been sufficiently studied.The aim. To study the prevalence and genetic variability of R. helvetica in Ixodes spp. collected in Western Siberia and the Russian Far East.Materials and methods. Ixodes spp. collected from rodents in the Omsk province, Western Siberia (n = 280) and collected by flagging on Putyatin and Russky Islands in Primorsky Krai, Russian Far East (n = 482) were analyzed for the presence of Rickettsia spp. All positive samples were genotyped for the gltA gene fragment. For a number of R. helvetica samples, fragments of the 16S rRNA, ompA, ompB, sca4, htrA, and groEL genes and 23S–5S intergenic spacer were additionally sequenced.Results. Four Rickettsia species (R. helvetica, “Candidatus Rickettsia tarasevichiae”, “Candidatus Rickettsia uralica”, and “Candidatus Rickettsia mendelii”) were found. Of them, R. helvetica was identified in 72.2 % of Ixodes apronophorus and 18.8 % of Ixodes trianguliceps from the Omsk province and in single Ixodes persulcatus from the Omsk province and Putyatin Island. This is the first finding of Rickettsia spp. in I. apronophorus. All known R. helvetica sequences from this study and the GenBank database belonged to four well supported monopheletic groups forming genetic lineages I–IV. Lineage I included European isolates from Ixodes ricinus, Western Siberian isolates from I. persulcatus, and some sequences from I. apronophorus. All R. helvetica sequences from I. trianguliceps from the Omsk province and I. persulcatus from the Komi Republic and one sequence from I. apronophorus were assigned to lineage II. Most sequences from I. apronophorus formed lineage III; all known R. helvetica sequences from I. persulcatus from the Far East formed genetic lineage IV.Conclusion. The genetic heterogeneity of R. helvetica population was first demonstrated. Known isolates of R. helvetica are reliably assigned to four genetic lineages, but not in all cases the association of different lineages with a specific tick species or specific territory was observed.

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.

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.

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 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.

There was a decrease in the number of COVID-19 cases across many entities of the Russian Federation towards the end of summer season-2020. However, the disease remains a relevant threat to the public health and economy and the possibility of a second epidemic wave is not excluded. Rate of infection transmission (Rt) is one of the most important indicators to justify the transition to next stage of removing/introducing restrictive measures on COVID-19.Objective of the work was to describe the algorithm of analysis and short-term forecast of coronavirus spread rate, to assess correspondence between theoretically expected and actual values of this indicator.Materials and methods. Procedure for making a short-term extrapolation forecast of Rt in 10 RF constituent entities, depending on the presence or absence of indicator trends with calculation of a 95 % confdence interval of possible changes in its value is provided.Results and discussion. It is proposed to carry out Rt forecast based on averaged values over a week, combining regression analysis and expert assessment of time series dynamics nature for prompt transition from trend forecasting to extrapolation of stationary observation sequences and vice versa. It has been demonstrated that predicted Rt values are not statistically different from actual values. When making managerial decisions on COVID-19 prevention, special attention should be paid to cases when actual value of Rt exceeds the upper limit of confdence interval. Six (20.0 %) such cases were detected in surveyed entities on calendar weeks 33–35. Three of them were registered in Trans-Baikal Territory, where upward trend was reported during that period of time. The cause of this phenomenon should be analyzed. The put forward algorithm of analysis and forecasting of the Rt value changes, which was tested in 10 entities of Russia, provides a reliable basis for making management decisions on removing/introducing restrictive measures for COVID-19 prevention.

Tick-borne encephalitis is a natural-focal infection damaging central nervous system, caused by the similarly-named virus transmitted by several species of ixodic ticks. Natural foci of tick-borne encephalitis (TBE) are widely spread in the forest and forest-steppe landscape zones of the temperate climate belt in the vast territory of Eurasia from the Atlantic to the Pacific Ocean. New TBE-endemic territories have been recently identified in Japan, the Netherlands, and in the UK – in 2019. The increasing risk of infection due to the development of tourism and visits to natural foci of TBE became a public health issue of international concern. The aim of the study is to identify modern features of TBE incidence dynamics in the Russian Federation, the state of laboratory diagnostics and prevention and to predict the incidence for 2021. The paper shows that there is a persistent downward trend in TBE-cases in Russia, which is observed through the past few years. The characteristic feature of the epidemic season-2020 was a significant reduction in the incidence of TBE: 989 cases were registered in 33 constituent entities of the Russian Federation (morbidity rate – 0.67 per 100 000 of the population). The sharp decrease of TBE cases in 2020 as compared to 2019 against the background of a decrease in vaccination can be explained, along with natural factors, by the introduction of restrictive measures during the COVID-19 epidemic. The paper also reflects the dynamics of morbidity, seeking the medical services because of tick bites, the infection rate of the carrier, the scope of vaccination, seroprophylaxis, acaricide treatments. The coverage of express-diagnostic tests of ticks for markers of associated pathogens and its availability for the population are presented. It is recognized that the epidemiological situation on TBE in the Russian Federation remains unfavorable. It demands constant attention on the part of healthcare organizations and Federal Service for Surveillance in the Sphere of Consumers Rights Protection and Human Welfare, as well as management decision making aimed at further decrement in TBE incidence through the improvement of prevention measures, specifically in the entities that are characterized by high TBE incidence. The situation requires monitoring of natural foci of infection, enhancement of prophylaxis and treatment of TBE. The paper provides the forecast of TBE incidence for 2021 and values of the 95 % confidence range of the indicator fluctuation, taking into account the presence or absence of trends in its changes in the territory of federal districts and constituent entities of the Russian Federation in 2011–2020.

The incidence of Ixodes tick-borne borreliosis (ITBB) at the Island Russky (Primorsk Territory) is higher than at the mainland. There is a bidominant structure of the tick population with mass occurrence of Ixodes persulcatus and I. pavlovskyi at the island. Due to the higher infectivity and aggressiveness of I. persulcatus, it is suggested that it plays a key role in high activity of the ITBB focus at the island.The aim of the study: to characterize the role of I. pavlovskyi in the borreliosis epizootic process based on the study of the structure of the borrelia genotype complex isolated from Ixodes ticks at the Island Russky.Materials and methods. The ticks were collected from vegetation at three sites. Ixodide species were determined morphologically and using PCR for mitochondrial gene cox1 and nuclear multicopy locus ITS2. Infection of 233 ticks was analyzed with the species identification confirmed by all methods. Borrelia genospecies were determined by multiplex two-round PCR with the primers specific to the gene fragments 5S and 23S rRNA of Borrelia burgdorferi sensu lato complex.Results and discussion. Coexistence of I. persulcatus and I. pavlovskyi at the island was confirmed, with different ratios in space and a gradual increase in the proportion of the latter species. The circulation of three etiological agents of ITBB: Borrelia garinii (predominantly in I. pavlovskyi), B. bavariensis and B. afzelii (in I. persulcatus) was identified. Thus, an active natural focus of ITBB has formed at the island, probably including two uninsulated chains of borrelia circulation. One chain combines I. persulcatus and small and large mammals as the tick feeders. The second – I. pavlovskyi that can feed on mammals and birds. Due to the spatial variability of the ixodide population structure at different sections of the island, the ratio of the circulating borrelia species can change, and this species becomes the main vector of the pathogenic agents in areas of I. pavlovskyi absolute dominance.

Assessment of a particular territory by its epidemiological significance is very relevant in the light of widespread occurrence of new coronavirus infection, COVID-19, in the Russian Federation.Objective. Detection of the epidemiological features and revealing trends in the epidemic process of new coronavirus infection in the Irkutsk Region and forecasting of its spread.Materials and methods. An operational analysis of the epidemiological situation on COVID-19 in the Irkutsk Region as of August 16, 2020 was performed. Restrictive measures were substantiated based on the calculation of the infection spread rate (Rt).Results and discussion. Irkutsk Region remained one of the adverse territories as regards human COVID-19 incidence in the Siberian Federal District and the Russian Federation as of August 16, 2020. The gradual dynamics of the epidemic process was revealed: at the first stage of the epidemic development it was facilitated by the imported cases from affected countries and regions of the Russian Federation, and subsequently by local transmission. The incidence increase was registered 2 months later than in central regions of the Russian Federation. Currently there is a consistent downward trend. The increase in the cases prevailed among rotation workers staying for shift and seasonal activities in the administrative center and northern districts of the Irkutsk Region. The epidemic pattern was determined by gender, age and social characteristics. It is demonstrated that the risk of the new coronavirus infection is determined by the intensity of contacts in family foci, the spread of infection in medical organizations and a significant proportion of asymptomatic carriers. High lethality rates (0.7 %) and mortality rates (31.1 o / oooo) were established among persons over 65 years. The stationary time series observed since June for changing the Rt-indicator with fluctuations ranging from 0.92 to 1.01 requires maintaining control of restrictive measures with prompt management decisions making based on the evolving epidemiological situation in the Irkutsk Region and taking into account the assessment of its possible complication risks.

Natural foci of plague – a particularly dangerous transmissible zoonotic disease – are widely spread across the world, including in the territory of Russia and a number of neighboring countries in Central Asia. Between 2000 and 2019, 28339 cases of plague were registered in 21 states around the world; lethality rates reached 8 %. Active plague manifestations are associated with the increase in the abundance of carriers and vectors of the disease, which increases the risk of human infection. Prophylactic measures against plague are aimed at prevention and eradication of epidemic foci; they incorporate a whole complex (system) of activities. Disinsection and deratization remain the most radical of them. Control of the numbers of carriers and vectors of plague involves decrement up to the levels at which epizooties will not develop, they are suppressed and liquidated. Currently in the Russian Federation and CIS countries, the focus is on the field and community disinsection when planning and performing exterminatory interventions. The decrease in the numbers of fleas – carriers and vectors of plague microbe – results in disruption of epizootic process and, consequently, in provision of epidemiological welfare as regards this dangerous disease. Insecticide treatments in natural biotopes are carried out using powder-like or aerosolized products, the class of pyrethroids, organophosphorous compounds and phenylpyrazoles by means of advanced equipment: knapsack dusters, power operated air blowers, and foggers. Within the boundaries of residential areas wet disinsection is performed with the help of spraying devices. Field deratization is allowed upon epidemiological grounds only, in localized territories of epizooties, within the boundaries of the settlements of plague infected carriers. Zinc phosphide- or anticoagulant-based bait products are used as rodenticides. Therewith, the eradication of valuable animal species, rare species of small mammals and endemic species is prohibited. Community deratization is always accompanied by the community disinsection. When planning and carrying out insecticide and rodenticide treatments the priority is given to the safety of handling the chemical preparations, to the exclusion of the negative effect on target animal species.

Objective of the study was to differentiate the Administrative Districts of theTransbaikalTerritory at the time of Tick-borne viral encephalitis (TBVE) incidence recession by epidemiological risk groups and to characterize them by volume of specific and nonspecific preventive measures.Materials and methods. Retrospective analysis of TBVE epidemiological situation is based on the statistical reporting data “Information on infectious and parasitic diseases” in 2009–2019 and other materials of the Rospotrebnadzor Administration in the Transbaikal Territory. The clustering of areas with various levels of epidemiological risk was conducted by calculation of 95 % confidential interval for long-term annual average of TBVE cases in municipal units of the Territory over a decade and assessment of appurtenance of the deviating values to the aggregate under study.Results and discussion. Twenty four out of 32 districts of the Transbaikal Territory are endemic for TBVE. These areas are divided into five groups: with very high epidemiological risk (2 districts), high (5), medium (8), and low (8) risk respectively, as well as the administrative center of the constituent entity which by the whole complex of indicators (disease manifestation, population density, factors of targeted TBVE decrease, social-and-living and economical conditions) cannot be considered together with the rest of municipalities. Each group of the districts was characterized by the number of cases and TBVE incidence rates, medical aid seeking by persons who suffered from tick bites, vaccination volumes, seroprevention, areas of acaricide treatments. Recommendations are presented for the essential complex and scope of measures to prevent TBVE in the groups of administrative districts that differ by the level of epidemiological risk.

Tick-borne encephalitis is a transmissible natural-focal disease which occurs in some countries across Europe and Asia. The observation of epidemic process dynamics of TBVE in Russia covers an 80-year long period and it’s the world longest. The existence of extensive records, various data from different geographic and administrative areas opens the way to interpretation of certain ecological and social factors and their role in the regional epidemiological situation. The targeted measures against TBVE are feasible only when the role of basic predictors of decreasing incidence is defined. Objective: analysis of TBVE incidence among the population and preventive measures in the Districts and constituent entities of Russia in 2019, forecast for 2020 based on the data collected in 2010–2019. The article shows a continued downward trend in TBVE incidence, noted in recent years. However, cases of infection were registered in 6 Federal Districts and 46 regions just like in the past. The number of patients amounted to 1559 (the incidence rate is 1.02 per 100000 people), of whom 23 have died. The rate of seeking medical care among those who were bitten by ticks increased. Specific preventive measures against TBVE haven’t significantly changed by volume and focus compared to the previous period. The scope of acaricide treatments has declined. The article also presents the data concerning TBVE carriers’ infection rate, and the laboratory study results in districts and regions across the country. It is recognized that the epidemiological situation on TBVE in Russia is still unfavorable. It requires the constant attention of health facilities and Rospotrebnadzor and management decisions aimed at further decrease in the incidence by improved prevention especially in the regions with high TBVE incidence.

Abstract. Despite the decreasing TBE incidence trend in Russia, the disease is considered an ongoing challenge for the state’s public health and economics. Objective of our study was to describe the algorithm of short-term incidence forecast of TBE, to evaluate the conformity of these data to factual incidence and the results of annual strategic seasonal monitoring which takes place across all the entities of Russia. In the paper, we described the procedure for providing short-term extrapolation of TBE incidence forecast onto the Russian territories, depending on the absence or presence of incidence change trends.Materials and methods. Utilized were the State statistics, “The data on infectious and parasitic diseases” (Form No 2), as well as the information on strategic monitoring for a period of 2007–2018. In order to determine the multi-year trend of epidemic process development, regression analysis was applied. If the trend was identified, predictions were made on its basis, if not – through calculating the long-term annual average. In all the cases, 95 % confidence interval for incidence trend deviation was considered. Comparative analysis of actual morbidity rates and predicted ones and the data on strategic monitoring was conducted by Student’s criterion.The commutations were performed using Excel software tools.Results and discussion. The study has demonstrated that the expected rates of TBE incidence are not statistically different from the actual incidence or the data from strategic monitoring. The underestimation of the epidemiological risk is found only in 4 out of 49 entities (8,2 %), and it is of note that in 3 of them it was less than 16 %. The data from operational monitoring are downward biased by reference to actual incidence, which is probably due to inclusion of TBE cases confirmed and/or manifested upon termination of incubation period after expiration of terms of weekly observations. The unified and simple approach that we proposed to TBE-incidence forecasting within the territory of Russia provides for correct information on expected epidemiological risk assessment and timely planning of required preventative measures.

Epidemiological situation on tick-borne viral encephalitis in the Russian Federation in 2018 was analyzed. Dynamics of the incidence, medical aid appealability among persons who suffered from tick suction, virus carriage of the vector; vaccination volumes, seroprophylaxis; acaricide treatment are reported in the paper. Utilized were the data on operative monitoring performed by the Rospotrebnadzor Institutions in the constituent entities of the Russian Federation and form data from the Federal statistical survey «Data on Infectious and Parasitic Diseases» over the period of 2009–2017, and also information from the operative monitoring, 2018. The increase in medical aid appealability among the population due to tick suctions was observed in all endemic Federal Districts (FD) of the European part of the Russian Federation during the epidemic season, 2018. The total of 1508 cases in 46 constituent entities of the country was registered: Siberian FD – 44.3 % of the cases, Privolzhsky FD – 22 %, Ural FD – 14.7 %, Northwest FD – 12.6 %,Central FD – 3.7 % , and Far Eastern FD – 1.7 %. Twenty two cases had lethal outcomes. Nation average infection rate of ticks taken off from humans was 1.38 %, from environment objects – 0.61 %. General level of tick infectivity was 1.5 times lower in 2018 as compared to 2017. The forecast of the incidence for 2019, taking into account the presence or absence of the trend fluctuations in the constituent entities in 2009–2018 and the values of the 95 % confidential interval of the possible parameter variations, is presented. The further gradual improvement of the epidemiological conditions for tick-borne viral encephalitis is expected. According to estimates, in 2019, morbidity rates will be 0.19 0/0000 in CentralFD, with value fluctuations ranging between 0.128 to 0.247 cases, in Northwest FD – 1.12 0/0000 (0.112 to 2.122 0/0000), Privolzhsky FD – 0.67 0/0000 (0↔1.649), Ural FD – 1.2 0/0000 (0↔4.590), Siberian FD – 3.4 0/0000 (1.319↔5.471), and Far Eastern – 0.65 0/0000 (0.522↔0.770).

The article presents the analysis of tick-borne encephalitis (TBE) epidemiological situation in the Federal Districts of Russia in 2017. Studied has been the effect of causative factors of epidemic process dynamics, such as: rate of people seeking medical help due to tick bites, contamination of ticks with the TBE virus revealed by immune-enzyme analysis and polymerase chain reaction, amount of people who were vaccinated, scope of emergency prophylaxis, the size of treated areas, and amount of funding for TBE-incidence decrease. Authors presented the incidence forecast for the endemic areas as regards TBE, as well as for the whole country for 2018, taking into account the presence or absence of change in its trends during 2008–2017. The values of the confidence interval are 95 % of the indicator fluctuations. Further gradual improvement of the epidemiological situation is expected.

Siberian tick-borne typhus (STBT) is a disease caused by Rickettsia sibirica, characterized by high indicators and degree of localization of manifestations in separate territories. Between 2009–2016, the total of 10190 STBT human cases was registered in the Siberian Federal District; it makes 80.4 % of the case numbers across the country. Objective of the study was retrospective estimation of dynamics of epidemic STBT manifestations in Siberian Federal District in 2009–2016 for forecasting epidemiological situation development and working out proposals for its stabilization. Materials and methods. Analysis of epidemic status of all the entities of the Siberian Federal District was performed on the basis of the State Statistical Reporting form No 2. Results and conclusions. Through calculation of the confidence interval for long-term annual average STBT values the entities were united in three groups which differ in the morbidity rate level. In territories with high intensity of epidemic process the tendency to further deterioration of epidemic status was observed (Altai and Tuva Republics, Altai Territory) which will negatively affect the incidence rate indicators across the country. To stabilize the situation with STBT manifestation, wider use of nonspecific preventive methods is required, as well as organization of etiotropic antibiotic therapy for persons who had been exposed to tick bites, on the basis of introduction of the test-systems for rickettsia detection at the emergency aid stations. In Altai and Tuva Republics, Altai Territory it is necessary to analyze the tactics of acaricide measures (sites, periods, frequency rate of treatments, acaricide dosages) taking into account the leading role of Dermacentor and Haemaphysalis genera representatives in rickettsia transmission.

A retrospective descriptive epidemiological study of an incidence rate and prophylaxis of tick-borne encephalitis (TBE) was carried out in the Republic of Khakassia over 2007–2016. Also, a relative risk (RR) of the incidence rate was assessed in the cohorts of vaccinated and unvaccinated population. Over the decade, 569 TBE cases were registered. There is a distinct tendency of TBE rate reduction (slope coefficient of the regression line b = –1.1 per annum, P < 0.05) as well as an expressed irregularity in the territorial distribution of longterm average annual rates in various towns and rural districts (from 0.9 up to 44.2 cases per 100 thousand people). In the vaccinated population cohort the TBE was registered 22.8 times less than in the unvaccinated one: χ2 = 23.78 (P < 0.001); RR = 3.1 (1.9–4.9). As the extend of mass-vaccination (b = 0.06 per annum, P < 0.05) and the area of acaricide treatments (b = 0.09 per annum, P < 0.05) were increasing, the number of virus-carrying ticks was reducing (b = –0.09 per annum, P < 0.001). The results of the comparison analysis of affect to the incidence of TBEcontrollable and uncontrollable factors in the territories with various rates of incidence prove the practicability of a risk-based approach to the prophylaxis of tick-borne encephalitis.

The results of archive data analysis of the tick-borne encephalitis (TBE) cases in Irkutsk during 1995 - 2015, got from Irkutsk Regional Center for hygiene and epidemiological surveillance, are shown. During the examined period the percent of severe forms and lethal outcomes of the disease have risen. The severe forms came more often at the very beginning and at peak of ticks’ activity season. The number of alimentary TBE cases, illness of anti-TBE vaccinated persons and persons with professional risk of infection have increased in Pribaikalie during 1995 - 2015. The recurring TBE cases have been also recorded.

Division of the Asian part of the Russian Federation into southern and northern zones was implemented on the basis of physical-climatic features. The retrospective analysis of the natural focal infectious diseases in humans was carried out. Spectrum of nosological forms and epidemic process intensity in each of the evolved zones were established. Epidemic manifestations were the most expressed in the Subjects belonging to the southern zone, with domination of the Ixodes tick-borne infections. In northern zone natural focal infections included 57,1 % of local cases, they were registered only in the population of Yamal-Nenets Autonomous Okrug (District), and barely nontransmissible infections: hemorrhagic fever with renal syndrome and rabies.

Epidemiological situation for tick-borne virus encephalitis (TBVE) in the Russian Federation is analyzed for the last twenty years (1997–2006 and 2007–2016). It is established that the last decade is characterized by decrease of the morbidity indicators in all constituent entities of the country attributed to the groups with high and middle intensity of the epidemic process, except for the Kirov region. Differences in the dynamics of morbidity decrease are revealed in groups of entities with various intensity of epidemic process in European and Asian parts of Russia. It is shown that at current period the epidemic process is the most intensive in the Asian part of nosoarea of TBVE. In short-term prospect the incidence rate is expected to be below average long-term indicators for 2007–2016 or slightly exceed them.

Aim. Evaluate the degree of epidemic risk of emergence of tick-borne encephalitis (TBE) and ixodes ticks’ borreliosis (ITB) in municipalities (MPs) of Irkutsk region with various natural-climate conditions. Materials and methods. Morbidity was compared for TBE and ITB during 2001 - 2015 in MPs of Irkutsk region located to the north or south of the 55th parallel, i.e. in the conditions of different severity of sharply continental climate. 5-year average data were analyzed. Results. ITB morbidity was 2 - 3 times higher than TBE for all the 5-year periods in the north of the region, whereas in the south -differences were not present. Moreover, in MPs located to the north of the 55th parallel in 2001 - 2015 a decrease of TBE and ITB morbidity did not occur, as in the south of the region. Conclusion. The lack of population morbidity reduction by TBE and ITB in the north and prevalence of the latter nosoform requires enhancement of a complex of prophylaxis measures in these MPs with an accent in development of non-specific means, including acaricidic treatment, enhancement of operations of centers of express diagnostics of transmissible infections, familiarizing of the population with the use of protective suits during periods of high activity of ticks.

Analyzed has been epidemiological situation and measures, performed for prophylaxis of tick-borne viral encephalitis in the territory of Russia in 2015. It is shown that the number of humans bitten by ticks increased in the majority of the constituent entities of the country. But specific and nonspecific preventive operations in 2015 were realized to a lesser extent as compared to 2014. Along with the natural factors, it might be the reason for increase in human tick-borne viral encephalitis morbidity rates. In total, 2116 patients with tick-borne viral encephalitis and 24 lethal cases were registered in the country. On the basis of the data regarding tick-borne viral encephalitis (TBVE) incidence rate among the population across the Federal Districts of Russia over a period of 2009-2015, forecasted have been intensive indicators of the clinical forms’ manifestations for 2016. TBVE morbidity rate in RF will amount to (1.90 ± 0.21)о/оооо. With 95 % probability it will be retained within a range of 1.4-2.4о/оооо.

Ticks’ ability to attack man (aggressiveness) is an important characteristic impacting the ticks’ epidemiological role. Objective of the study is to assess the aggressiveness of the ticks inhabiting the south of the Primorsky Territory. It is based on the materials collected in the territory of Partizansky Region in 2012-2013. Ticks’ aggressiveness toward man has been defined by comparing the species’ community structure when collecting imago specimens on a cloth from plants (3,944 specimens are examined) and when removing ticks from people (437). In total, five species are identified: Ixodes persulcatus , Haemaphysalis concinna , H. japonica douglasi, Dermacentor silvarum (being dominant species), and I. pavlovskyi (which is rarely found in Partizansky Region) . Cases of tick attacks have been registered during April through October and November: this period being the peak of activity in I. persulcatus , and activity decay in H. concinna. The percentage of I. persulcatus against the total number of ticks, removed from people, has amounted to 86.3 %; the percentage of the same species collected from plants has amounted to 44.9 %. This is maximum index of aggressiveness. I. pavlovskyi also shows high level of aggressiveness, but as it is of rare occurrence it does not have any epidemiological weight in Partizansky Region. H. japonica attacks more often than H. concinna. In order to assess the difference in the epidemiological significance of these two species individual infection rate should be studied. As for D. silvarum, the percentage of this species removed from people is lower than that collected from plants, thus currently the epidemiological significance of this species in the south of Primorsky Territory is relatively low.

The current research is aimed at studying the changes in a ratio of symmetrical to asymmetrical forms based on the counting bilateral characters in Ixodes persulcatus samples in various living conditions. Phenotypic variation was described with the following indices: (of) for a dispersion of the number of bristles at the left and right side; (Sa) for actual and (St) for theoretical number of symmetrical specimens with the supposition of an independent manifestation of such characters at the both sides of a body; and the difference between Sa and St. 4 bilateral characters were studied on the coxae of the fourth leg of the ticks collected by dragging off the plants outside Irkutsk (299 specimens) and Bratsk (156 specimens). The both territories are characterized by an excess of Sa and St. The σd2 value was proved to be higher among the ticks outside Bratsk where they live in a difficult environment. Given that no differences were revealed in the average values of «Sa-St» index, being characteristic of a subdivision of samples, the observed difference in of values may be considered as a prove of an increased instability during ontogeny under adverse circumstances.

Species composition and contamination by the causative agents of natural focal infections, notably Ixodes ticks, collected in 2014–2015 on the Island Russky were studied. The total of 817 ticks was collected, including Ixodes persulcatus, I. pavlovskyi, Haemaphysalis concinna, H. japonica douglasi. The most of the nymphs (46 specimens) were observed in I. pavlovskyi. Using immune-enzyme analysis, reliably higher rate of positive findings was revealed in I. pavlovskyi (2.2 %) compared to I. persulcatus (0.5 %) while analyzing individual contamination of two Ixodes species. The pattern of inter-specific distinctions did not changed (I. pavlovskyi – 1.3 %; I. persulcatus – 0.5 %) when investigating tick virus burden by means of polymerase chain reaction. However, in case of comparative evaluation, using the same method, of their contamination with borrelia (I. pavlovskyi – 25.1 %; I. persulcatus – 46.4 %), agents of granulocytic anaplasmosis (I. pavlovskyi – 1.9 %; I. persulcatus – 5.7 %) and monocytic ehrlichiosis (I. pavlovskyi – 1.3 %; I. persulcatus – 7.2 %) I. persulcatus showed higher indicators. Only tick-borne encephalitis RNA and borrelia DNA were revealed in I. pavlovskyi nymphs, whereat their contamination by spirochetes (45.7 %) was authentically higher than of imagoes. The natural focus of tick-borne encephalitis on the Island Russky is estimated now as low-active one. At the same time, of Ixodes tick-borne borreliosis – as active, with significant contamination of the tick nymphs with spirochetes. In terms of high nymph contamination it is supposed that in 2016 the risk of Ixodes tick-borne borrelioses morbidity rate will increase for humans visiting the Island within the period of high vector activity (May– June).

Comprehensively studied have been structural elements of ecosystems of Siberian natural plague foci, as well as levels of integration among epizootic process components, and ways of their functional interaction. Application of the complex approach to the surveillance over structural-functional elements of the parasitic system along with investigations of epizootic process dynamics has provided for identification of peculiarities as regards epizootics development, transformation and evolution of population and carrier/vector coenosis structure in time and space. Revealed is the genetic diversity of plague microbe circulating within the bounds of separate foci and zones of focality. Determined is a long-lasting anti-epidemic effect (more than 20 years) of the field desinsection in the Saglinsk meso-focus of the Tuva natural plague focus.

Summarized are the results of the work on provision of sanitary and epidemiological well-being during the arrangement and carrying out the APEC Summit on the Russky Island. The set of organizational and prophylactic measures aimed at prevention of potential danger of emergency situation of sanitary and epidemiological character is presented. Measures on provision of epidemiological well-being of the participants and guests of the APEC Summit, based upon interaction of the regional plague-control institutions with anti-epidemic and health services of the Primorsky Region, demonstrated their efficiency. Epidemiological situation on the Russky Island and Vladivostok city was safe. The materials presented can be used to develop a set of measures ensuring the epidemiological well-being during large scale political and economic events holding at the national and international levels.

Analyzed is the incidence rate as regards natural focal infections of bacterial and viral etiology. Displayed is the data on the performed laboratory diagnostics of these infections in the territory of Siberia and Far East in 2012 and forecast of the epidemiological situation development in 2013. Analysis is carried out based on the data received by the Reference Center for surveillance over natural focal infections at the Irkutsk Research Anti-Plague Institute, from Rospotrebnadzor Institutions of Siberian, Far-Eastern and Ural Federal districts, as well as reviews and prognoses on the current state of natural foci of infections available from Altay, Tuva, Chita, Khabarovsk and Primorsk plague control stations.

Analyzed are the epidemiological situation and preventive measures against tick-borne encephalitis in the territory of the Russian Federation in 2012. Short-term forecast for 2013 is made based on the population morbidity rate in the federal districts of Russia in 2007–2012.

In spring, 2011 within the frames of epizootiological survey of the Isle Russian territory, identified were five species of Ixodic ticks: Ixodes persulcatus, I. pavlovskyi, Haemaphysalis concinna, H. japonica douglasi, Dermacentor silvarum. Those ticks were infected with the agents of tick-born encephalitis, borreliosis, rickettsiosis, and monocytic ehrlichiosis. Further preparations for the hosting of APEC Summit in the territory of the Isle in September 2012 involve large-scale construction of various facilities, transformation of natural biotopes, and significant increase in population numbers both permanently and temporally residing in the region. In this connection, a complex of preventive measures aimed at protection of local population and participants of the Summit from tick-borne infections is currently under consideration.

Disinfestation and deratization remain the main ways of non-specific disease prophylaxis in natural plague foci. Modern strategies, tactics, methods and means of control over carriers and vectors of plague and associated infectious diseases are selected with due consideration to epidemiological potential of territories, epizootic activity of a foci, peculiarities of population ecology of animals that are of a medical significance, preservation of biodiversity in natural ecosystems, and the requirements for human and natural environments protection from pollutants.

Analysis of the epidemiological situation on the tick-borne viral encephalitis in the territory of the Russian Federation with due consideration to weekly epidemiological monitoring data (2009-2011), conducted by Rospotrebnadzor organizations in the corresponding constituent entities, testifies of the fact that continuous decrease in morbidity, characteristic of the early XXI century, has given way to a slight increase within the past three years. Given that there are no spring or early-summer weather anomalies or forest fires, morbidity rates among the population of the Russian Federation in 2012 can tend to exceed 2011 rates. Comprehensive set of measures applied for the disease control and prevention in the majority of endemic territories is quite effective in view of averting sharp upturn of morbidity rates, but nevertheless is not sufficient in view of the suppression of epidemiological situation.

Presented are the data on tick-borne infections (tick-borne encephalitis, tick-borne borrelioses and rickettsioses) incidence among the population of the constituent entities of Siberian and Far East Federal Districts in 2009 and 2010. Given is the prognosis on tick-borne encephalitis and tick-borne borrelioses incidence among the population of the Districts for 2011. Generalized information on the amount of preventive measures is presented and the ways of their improvement are discussed.

Objective of the work was to estimate the number and state of the small mammal populations after the summer flood, 2013 in the territory of the Amur Region and make short-term forecasting of the epidemiological situation development. Carried out was small animals capturing using Gero traps with bread as a bait. Epizootiological surveillance in August-September 2013 indicated that the numbers of small mammals did not differ from the average annual rates, but the process of active reproduction in the populations was being underway. In October-November a sharp increase in the animal abundance rate was registered, reproduction process terminated. Large-scale flooding resulted in the formation of local settlements with a high animal density. Stress, aggressiveness and food ration change along with seasonal migration of rodents into human buildings predetermined epizootiological and epidemiological premises for onset of natural-focal infections. Therewith the conclusion was made up that it was necessary to perform epizootiological monitoring of the small mammal populations and realization of measures aimed at the rodent extermination in human settlements in 2014.

Plague epidemiological situation in India in XX and at the beginning of XXI century is evaluated. The epidemic process is shown to have wavy interrupted course and is divided into periods of annual intensive epidemics, reduction of epidemic activity and sudden development of acute outbreaks on the background of sporadic morbidity absence. Brief characterization of a pulmonary plague epidemic in India in 1994 and undertaken international sanitary and protective measures by the example of Russian Federation and USA is presented. Local outbreaks of pulmonary and bubonic plague in 2002-2004 give evidence of periodically complicated epidemic situation in India. Trend and volume of measures on sanitary protection of territories are substantiated by development of commercial, economical, tourist communications between India and Russia including Regions of Siberian and Far Eastern Federal Districts differing by the degree of plague importation risk.

Performed was analysis of long-term dynamics of tick-borne encephalitis (TBE) morbidity, the taiga ticks abundance, number of bites to which urban residents had been subjected, imago virus carriage. All these indices were shown to change in a cyclic manner. Worsening of TBE epidemiological situation was prognosticated in Siberia for the period of 2009-2010. Plans of preventive measures, optimally combining both specific and non-specific ones, should be elaborated for the areas with the highest risk of TBE infection for humans, taking into consideration increased epidemiological danger of the region, presence of mixed infections in ticks, social structure of the population.

The level of fluctuating asymmetry (FA) of bilateral signs in fleas was shown to reflect a certain character of their interrelations with Yersinia pestis. Flea imagoes that had bacterial aggregations in their proventriculi demonstrated greater signs of FA chaetotaxy. Besides, in the experiments with groups of fleas originally differing in the intensity of FA expression, increased vector capacity was characteristic of individual fleas with higher levels of this index or those caught in the areas of the natural foci where epizootics had been registered. These peculiar interrelations manifested themselves both at intra- and inter-population levels in several species of Siphonaptera order, as well as in the imago hybrids originating from crosses between C.tesquorum altaicus and C.t.sungaris.

In April-June 2012 a collection and analysis of structure of Ixodes tick communities was performed in various biotopes at the Primorye Territory. Five tick species (Ixodes persulcatus Schulze, 1930, I. pavlovskyi Pomerantzev, 1946, Haemaphysalis concinna Koch, 1844, H. japonica douglasi Nuttall et Warburton 1915, Dermacentor silvarum Olenev, 1932) were revealed. It was shown that I. pavlovskyi was rare at the continental part of the Primorye Territory, but it often happened at the Russian island. On the Continent H. japonica douglasi prevailed over H. concinna in total collections. Correlation of these species at the Russian island was reversed. Distinctions in the structure of Ixodes tick communities, formed due to specificity of ecological conditions and. long enough isolation of the parasites' fauna at the island, could affect the ratio and. features of the causative agents of the human infectious diseases for which the carrier organism serves as the first environment.

Data of the experimental investigation, using typical for the focus virulent Yersinia pestis subsp. pestis strains were analyzed to detect special features of a plague microbe biofilm formation (conglomerates, «blocks») in the main plague carrier, Citellophilus tesquorum altaicus fleas, in Tuva natural focus. It was established that biofilm (bacterial «blocks») played the important role both in plague transmission, by fleas and also in the agent preservation, by these insects. Results of the analysis indicated the prevailing significance of C. tesquorum. altaicus females in plague agent preservation and. explained some mechanisms of its survival in fleas during a cold season in Tuva natural plague focus. Under adverse conditions during the autumn period Y. pestis biofilms («blocks») accumulate mainly in a digestive tract of the main carrier females and. so can survive in fleas for a long time.

The following factors have been used to characterize 12 species and subspecies of fleas (Siphonaptera) and plague microbe (Yersinia pestis subs. pestis): the proportion of fleas with “blocks”, “blockules” and their ratio, called the index of microbe aggregation. The block formation is registered in 10, whereas formation of blockules are registered in all of the studied species and subspecies of Siphonaptera , the difference between active and passive transmitters according to the last characteristics being unreliable. The fleas, among of which “blocked” ones are not revealed in the experiments, are capable to transmit the causative agent of plague, sometimes with generalization of infectious process in animals, that can provide for continuous transmission of microbe without formation of “blocks” in the proventriculus. Thus, the high value of “rate of block formation” does not reflect the existence of coevolution in the interactions between microbe and its transmitter.

Investigation of the spatial-temporal variability of characteristics with alternative variation in females of taiga tick from three district of the Irkutsk Region showed all samplings to be phenotypically heterogenous. Based on these results estimated was L.A.Zhivotovsky criterion of identity between separate imago collections. Similarity index for geographically remote populations was about 0.9. This index was higher in intrapopulational groups collected from one territory in different seasons. The elucidated variability creates the basis for selection of morphologic tags of vector transmitting capacity and ticks life cycle duration and other questions of their biology investigation which includes usage of collection materials accumulated previously.