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 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.

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.

Aim. To study the diagnosis of legionellosis in patients who died because of pneumonia in Irkutsk (2016-2018).Materials and Methods. We performed 65 autopsies of patients who died from pneumonia in Irkutsk (2016-2018), studied their case histories, and interrogated 510 tap water samples for Legionella pneumophila by means of inoculation and polymerase chain reaction.Results. Among 65 fatal pneumonia outcomes registered in Irkutsk during 2016-2018, legionellosis has been confirmed in three cases (4.6%). Two of these patients were at the late stages of HIV infection while the third, 74-yearold, patient had multiple comorbid conditions. Nosocomial infection was suspected in one of these cases. None of these three patients left Irkutsk during the last month of their life. The assumed transmission factor was tap water, as Legionella pneumophila was found in tap water samples collected in 2013 and 2015.Conclusion. Patients with severe pneumonia need screening for legionellosis to perform the correct treatment, particularly during COVID-19 pandemic.

Retrospective analysis of sickness rate of infectious diseases demanding realization of measures for sanitary protection of the Russian Federation territory and actual high contagious nosologies that epidemic manifestations can form an epidemiological emergency situation is carried out on the basis of the data of World Health Organization and Federal Service for Surveillance on Consumers’ Rights Protection and Human Wellbeing with use of a technique for organization of sanitary anti-epidemic support of mass actions with the international participation (МR 3.1.0079/2-13). It is established that human flu caused by a new virus subtype, cholera, Lassa fever, illnesses caused by Ebola and Marburg viruses and also measles, rubella and acute enteric virus infections forming the external epidemiological risk during the XXIX Winter Universiade 2019 in Krasnoyarsk city represent the greatest threat. High risk of the disease importations demanding realization of actions for sanitary protection of Russian territory is connected with the countries of Eastern, Southern and South Eastern Asia, Africa (except for the Continent south) and also North America.

Retrospective analysis of sickness rate of infectious diseases demanding realization of measures for sanitary protection of the Russian Federation territory and actual high contagious nosologies that epidemic manifestations can form an epidemiological emergency situation is carried out on the basis of the data of World Health Organization and Federal Service for Surveillance on Consumers' Rights Protection and Human Wellbeing with use of a technique for organization of sanitary anti-epidemic support of mass actions with the international participation (МR 3.1.0079/2-13). It is established that human flu caused by a new virus subtype, cholera, Lassa fever, illnesses caused by Ebola and Marburg viruses and also measles, rubella and acute enteric virus infections forming the external epidemiological risk during the XXIX Winter Universiade 2019 in Krasnoyarsk city represent the greatest threat. High risk of the disease importations demanding realization of actions for sanitary protection of Russian territory is connected with the countries of Eastern, Southern and South Eastern Asia, Africa (except for the Continent south) and also North America.

Total 728 Ixodes ticks of four species: Ixodes persulcatus, I. pavlovskyi, Haemaphysalis concinna, H. japonica douglasi collected at the Russian island in 2011-2012 were investigated. Common Rickettsia infection rate in the tested vectors varied from 4.1 to 27.9%, and the most infected representatives turned out I. persulcatus and I. pavlovskyi - 27.9 and 10.0%, respectively. Sequencing and the phylogenetic analysis of fragments of citrate synthase genes (gltA) and ompA and ompB surface proteins revealed Rickettsia DNA in ticks of Ixodes genus belonging to Candidatus Rickettsia tarasevichiae, and in ticks of Haemaphysalis genus - to Candidatus R. principis. DNA of tick-borne epidemic typhus agent - R. sibirica and R. heilongjiangensis, failed to find in the ticks tested.

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).

This paper studies a full nucleotide sequence of cryptic plasmid pTP33, which was isolated from the typical plague strain of the Tuvinian natural focus, Yersinia pestis I-2638. Sequencing was carried out using the 454 GS Junior platform (Roche). In analysis using the software package GS De Novo Assembler v. 2.7 (Roche) and the algorithm Newbler v. 2.7, 1855 nucleotide reads, which contained 1101246 nucleotides, were assembled to a contig of 33 978 bp. The GC content of the obtained nucleotide sequence was 50.25%. During annotation, we found 56 open reading frames. Homologs of the predicted reading frames were sought in the BLAST databases. We detected 22 reading frames coding hypothetical proteins, 23 frames coding phagerelated proteins, and 11 frames coding proteins with known functions, including toxin–antitoxin system YefM-YoeB, nucleic acids and polysaccharides metabolism proteins (exopolysaccharide production protein ExoZ, exodeoxyribonuclease VIII), and replication proteins (ParA). Some predicted pTP33 proteins were found to be homologs (from 45 to 75%) with sequences of phage-related proteins of certain microorganisms—endosymbionts of insects (Sodalis glossinidius) and endosymbionts of entomopathogenic nematodes (Photorhabdus luminescens, P. asymbiotica, Xenorhabdus bovienii).

Objective of the work was to carry out complex assessment of the current state of epizootic activity and epidemiological significance of the infectious disease natural foci in the Aleksandrovsk-Sakhalin territory of the Sakhalin Region. Trapped were 56 samples of small mammals in July, 2010; collected were 180 specimens of taiga tick imago, caught were 1000 specimens of mosquitoes. 223 samples of blood sera were taken from residents of the region. All the field data were tested to detect specific antibodies, antigens and genetic material of agents. Based on the results of epizootiological investigations, serological and molecular-genetic assays, demonstrated was the occurence of natural foci of leptospirosis, tularemia, tick-borne encephalitis, borreliosis, rickettsiosis, human granulocytic anaplasmosis, human monocytic ehrlichiosis, West Nile fever, Inco fever, Batai and Geto fevers, as well as HFRS with varying degree of activity manifestation in the territory of the region. Isolated was tick-borne encephalitis virus from mosquitoes.

Displayed are the results of examination of immuno-competent local population of the Khabarovsk Territory, the Jewish Autonomous Region, the Amur Region, as well as foreign residents living and temporarily working in the areas, on a wide range of natural-focal bacterial and viral infectious diseases including the causative agents of some “exotic” infections too. Investigations have been carried out with the participation of experts from the specialized anti-epidemic team No. 1 (Irkutsk Research Anti-Plague Institute), who worked in the Amur Region, and a group of laboratory-epidemiological specialists from the team No. 2 - deployed in the Khabarovsk Territory and the Jewish Autonomous Region during the flooding in August-September 2013. The total of 1335 blood sera samples has been tested using serological methods. The findings have revealed the presence of immuno-competent population in the three regions of the Far Eastern Federal district in reference to the agents of natural-focal infectious diseases: tularemia, leptospirosis, yersinioses, hemorrhagic fever with renal syndrome, human granulocytic anaplasmosis, tick-borne borrelioses, tick-borne viral encephalitis, Californian encephalitis serogroup, Sindbis, West Nile and Dengue fevers. Circulation of Batai and Crimean-Congo hemorrhagic fever viruses has not been revealed based on serological assays.

Objective of the work was to carry out complex assessment of the current state of epizootic activity and epidemiological significance of the infectious disease natural foci in the Aleksandrovsk-Sakhalin territory of the Sakhalin Region. Trapped were 56 samples of small mammals in July, 2010; collected were 180 specimens of taiga tick imago, caught were 1000 specimens of mosquitoes. 223 samples of blood sera were taken from residents of the region. All the field data were tested to detect specific antibodies, antigens and genetic material of agents. Based on the results of epizootiological investigations, serological and molecular-genetic assays, demonstrated was the occurence of natural foci of leptospirosis, tularemia, tick-borne encephalitis, borreliosis, rickettsiosis, human granulocytic anaplasmosis, human monocytic ehrlichiosis, West Nile fever, Inco fever, Batai and Geto fevers, as well as HFRS with varying degree of activity manifestation in the territory of the region. Isolated was tick-borne encephalitis virus from mosquitoes.

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.

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.

Eighteen polytypic tick-borne encephalitis virus (TBEV) strains containing the fragments of E and NS1 protein genes of Siberian and Far Eastern, occasionally Siberian and European subtypes were isolated in the European and Asian parts of the tick-borne encephalitis (TBE) area. They were identified using real-time polymerase chain reaction, hybridization-fluorescence detection with genotype-specific probes, restriction fragment length polymorphism analysis, and E protein sequencing. The polytypic strains were isolated from individual Ixodes persulcatus ticks, their pools, from the blood of patients and the brain of dead patients. The isolation rates of the polytypic strains in the sympathry area of different TBEV subtypes ranged from 4.4% (the Irkutsk Region) to 15.1% (the Yaroslavl Region). In addition to 2 polytypic strains, a strain similar to the TBEV 886-84 strain was isolated. The TBEV subtypes entering into the composition of the polytypic strains show nongenetic interactions, such as neutral replication or competition. The polytypic strains are stable during passages in the cultured pig embryo kidney epithelial cells and on cloning. Mouse brain passage promotes dissociation of polytypic strains. The conditions for the formation of polytypic strains and their role in the etiology of TBE are discussed.

Irkutsk residents are infected, with, tick-borne encephalitis (TBE) mainly in Pribaykalie (Irkutsk region and Buryat Republic). TBE foci are rather various on this territory. Differences in some parameters of morbidity structure at the infection in different areas of this territory are reviewed, in this article.

Eighteen polytypic tick-borne encephalitis virus (TBEV) strains containing the fragments of E and NS1 protein genes of Siberian and Far Eastern, occasionally Siberian and European subtypes were isolated in the European and Asian parts of the tick-borne encephalitis (TBE) area. They were identified using real-time polymerase chain reaction, hybridization-fluorescence detection with genotype-specific probes, restriction fragment length polymorphism analysis, and E protein sequencing. The polytypic strains were isolated from individual Ixodes persulcatus ticks, their pools, from the blood of patients and the brain of dead patients. The isolation rates of the polytypic strains in the sympathry area of different TBEV subtypes ranged from 4.4% (the Irkutsk Region) to 15.1% (the Yaroslavl Region). In addition to 2 polytypic strains, a strain similar to the TBEV 886-84 strain was isolated. The TBEV subtypes entering into the composition of the polytypic strains show nongenetic interactions, such as neutral replication or competition. The polytypic strains are stable during passages in the cultured pig embryo kidney epithelial cells and on cloning. Mouse brain passage promotes dissociation of polytypic strains. The conditions for the formation of polytypic strains and their role in the etiology of TBE are discussed.

Six hundred and ninety three cases of ixodid tick-borne borreliosis in Irkutsk city residents duing17-year period. (1995-2011) have been analyzed. It was revealed that the most risk of Borrelia burgdorferi infection is for visitors of zones along Baikalsky, Goloustnensky and. Melnichny routes as well as green zones in Irkutsk from the end. of May up to the beginning of July. Individuals older than 40 years of both sexes suffer from the disease more often. Erythema is marked in more than 80 % of patients. Body is character place of the tick's bite for adults, head - in children.