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The aim of the work was to study the epidemiological situation on West Nile fever (WNF) in the Republic of Tatarstan in 2023.Materials and methods. An operational epidemiological analysis of WNF cases registered in the Republic of Tatarstan in 2023 was performed. In order to establish sources and risk factors for infection of the population, 987 samples of zoo-entomological material were examined for the presence of West Nile virus (WNV) markers. A set of laboratory diagnostic methods was used: ELISA, RT-PCR, sequencing.Results and discussion. It has been established that all cases of WNF were registered in the region in the summer-autumn period of 2023, mainly in August, among residents of the city of Kazan who had not traveled outside the Russian Federation and the Republic of Tatarstan over the past six months. The incidence rate of WNF in the Republic of Tatarstan was 0.20 per 100 thousand population, the mortality rate reached 12.5 %. Signs of damage to the central nervous system were present in 6 out of 8 (75 %) patients. The majority of people with severe clinical symptoms belonged to older age groups and had concomitant diseases. Cases of the infection were reported in all age groups, with the exception of children and adolescents. The spatial characteristics of morbidity have been investigated, indicating the diffuse nature of the distribution of cases. The integrated use of methods, consisting in the concurrent use of polymerase chain reaction and enzyme-linked immunosorbent assay, made it possible to laboratory confirm cases of WNF in patients at different stages of the disease. The circulation of a subvariant of the WNV of the second genotype in the Republic of Tatarstan, currently dominant in the southern and central regions of Russia, has been established. A set of measures has been proposed to optimize epidemiological surveillance and control of WNF in the Republic of Tatarstan.

The novel coronavirus (SARS-CoV-2) pandemic, dubbed COVID-19, has become one of the most serious challenges for human populations in the vast majority of countries worldwide. Rapid spreading and increased mortality related to it required new approaches to manage epidemic processes on a global scale. One of such approaches was based on analyzing SARS-CoV-2 seroprevalence associated with COVID-19. Our aim was to summarize the results on assessing seroprevalence to the SARS-CoV-2 nucleocapsid antigen (Nc) in residents from 26 regions of the Russian Federation, carried out during the first wave of the COVID-19 epidemic.Materials and methods. Seroprevalence distribution was examined in 26 model regions of the Russian Federation according to the unified method developed by the Rospotrebnadzor with the participation of the Federal State Institution Saint Petersburg Pasteur Research Institute of Epidemiology and Microbiology. Such approach implied formation of a group of volunteer subjects in model geographic region who were tested by ELISA for anti-Nc serum antibody level in peripheral blood. Analyzed primary data obtained in separate regions were either accepted for publication or released.Results. The current paper finalizes the data obtained in all 26 regions of the Russian Federation. The total SARS-CoV-2 seroprevalence was 19.5 (10.0–25.6)% with the maximum and minimum value found in the Kaliningrad Region and the Republic of Crimea, respectively (50.2% vs. 4.3%). A pattern of age-related seroprevalence distribution indicates insignificant predominance of seroprevalence among subjects of 1–17 years old: 22.1 (13.1–31.8)%. Among COVID-19 convalescents positive for SARS-CoV Nc antibodies it reached 60.0 (40.0–73.3)%. The number of contact persons comprised 6285 subjects or 8.5% of total volunteer cohort, with the level of seroprevalence reaching up to 25.3 (17.95–35.8)%. A direct correlation was revealed between levels of seroprevalence in convalescent and contact volunteers. In addition, the reproductive number for SARS-CoV was calculated comprising 5.8 (4.3–8.5) suggesting that one convalescent subject can infect at least 4 healthy individuals. A high level of asymptomatic forms of COVID-19 among seropositive subjects was confirmed empirically comprising up to 93.6 (87.1–94.9)%.Conclusion. A single cross-sectional study performed during 2020 June–August timeframe allowed to assess pattern of sex- and agerelated COVID-19 seroprevalence for general population in 26 Russian Federation regions. The data obtained may serve as a basis for the longitudinal cohort investigation with serial subject sampling. The timing and duration of study will be determined by dynamics of ongoing COVID-19 epidemic.

In late 2019, there were reports of an outbreak of infection caused by a new strain of beta coronavirus SARSCoV-2, the WHO identified the disease as coronavirus disease 2019 (COVID-19). In Tatarstan, the first case of COVID-19 was diagnosed on March 16, 2020, it was an imported case from France. The period of increase in the incidence lasted during the 12th to the 19th week, when the highest rate was recorded, amounting to 16.7 per 100 thousand population. Subsequently, a statistically significant decrease in the incidence was noted. Seroprevalence study was conducted at week 27 (8th week of decline of morbidity).The purpose of the seroepidemiological study was to measure the level and to identify the structure of herd immunity against the SARS-CoV-2 virus among the population of the Republic of Tatarstan during the rapid spread of the COVID-19 outbreak.Materials and methods. The selection of volunteers for the study was carried out by the method of questionnaires and randomization by random sampling. The exclusion criterion was active COVID-19 infection at the time of the survey. 2,946 people were examined for the presence of specific antibodies to SARS-CoV-2. The age of the surveyed volunteers ranged from 1 year to 70 years and older.Results. The results of the study showed that in the Republic of Tatarstan during the period of COVID-19 incidence, there was a moderate seroprevalence to SARS-CoV-2, which amounted to 31.3%, against the background of a high frequency (94.5%) of asymptomatic infection in seropositive individuals who did not have a history of past COVID-19 disease, positive PCR result and ARVI symptoms on the day of the examination. The maximum indicators of herd immunity were established in children aged 7–13 years (42.0%), children 14–17 years old (40.3%), with a simultaneous decrease in seroprevalence in persons aged 70 and older (24.0%). In different regions of the Republic of Tatarstan, there was a wide variation in seropositivity results from the minimum in the Zainsky district (8.6%) to the maximum in the Arsky district (74.3%). In 21 out of 38 surveyed districts, the results were unrepresentative due to the small sample size. In COVID-19 convalescents, antibodies are produced in 83.3% of cases. In persons with a positive result of the PCR analysis carried out earlier, antibodies were detected in 100% of cases. Among the volunteers who had contact with patients with COVID-19, the proportion of seropositive is 37%Conclusion. The dynamics of seroprevalence among the population of the Republic of Tatarstan can be qualified as positive, the results obtained can be used to develop a forecast for the development of the epidemiological situation, as well as to plan measures for specific and non-specific prevention of COVID-19.

Objective – assessment of effectiveness of the measures for biological safety provision at potentially hazardous facilities in the territory of the Republic of Tatarstan in the process of preparation and holding of FIFA World Cup-2018 in Kazan. Materials and methods. Regulatory-legal acts covering the requirements to the provision of biological safety during the work with pathogenic biological agents, international guidelines and documents determining inter-agency collaboration between the Rospotrebnadzor Administration in the Republic of Tatarstan and other departments and inter-agency task forces (Office of the Federal Security Bureau of Russia in the Republic of Tatarstan, Counter-Terrorism Commission in the Republic of Tatarstan, etc) were studied. Results and discussion. Considered were managerial-methodological approaches and matters of inter-agency cooperation on biological safety provision during preparation and holding of FIFA World Cup-2018 in Kazan. Biological safety was examined through the prism of its provision while working with pathogenic biological agents at potentially hazardous biological facilities and counterterrorism integrity of the objects. The guiding, directive document in the performance of the complex of measures on biological safety provision and inter-agency collaboration was the Order of the President of the Russian Federation dated May 09, 2017 No 202 “On peculiarities of application of reinforced security measures during holding of FIFA World Cup-2018 and FIFA Confederations Cup-2017 in Russia”. As the result of the measures conducted, biological safety, including counter-terrorism security of potentially hazardous biological objects and sanitary-epidemiological welfare, was fully provided.

Relevance. Within the framework of the state assignment in the, Kazan Scientific Research Institute of Epidemiology and Microbiology together with the Department of Rospotrebnadzor in the Republic of Tatarstan, the analysis of the tensions of collective immunity to measles in at-risk groups among medical workers, students of medical colleges in Kazan, Naberezhnye Chelny, Buinsk and Muslyumovsky districts for the period 2015‒2017.Materials and methods. Immunoenzyme method of analysis studied the intensity of immunity against measles in 1107 serum samples of medical workers from 19 medical and preventive institutions in cities and some regions of the Republic of Tatarstan, and students of medical schools and colleges.Results. It was established that out of 480 medical personnel, 363 (75,63 ± 2,253%) were seropositive to the measles virus, and 117 (24.38 ± 3.969%) were seronegative. Coverage by vaccination and revaccination against measles among the sample group of medical workers did not reach the level of 93% (84.38 ± 1.657%), which does not prevent the outbreak of measles among this group. According to the results of a sample survey of antibodies to measles virus among students of medical schools and colleges of the Republic of Tatarstan (data for 2016 and 2017), it was found that the proportion of seronegative measles virus among students in large cities of the Republic of Tatarstan in 2016 was 52.35 ± 2,99%, and in 2017, 42.32 ± 2.958% of the people. The proportion of students who were seronegative for measles virus for two years of the study (2016–2017) averaged 45.07 ± 2.979%.Discussion and conclusions. The results indicate the need to continue conducting studies on seromonitoring of collective immunity to measles in medical workers, students in secondary and higher medical schools.

Objective of the study was to describe the organization of epidemiological surveillance over internal risks associated with the intensification of natural-focal diseases in the Republic of Tatarstan, analysis of the measures taken to prevent natural focal diseases during the preparation and holding of the FIFA World Cup-2018. Materials and methods. The data from surveys and forecasts as regards the numbers of small mouse-like rodents as carriers and arthropod vectors of natural-focal diseases, epizootic and epidemiological situation reports in the Republic of Tatarstan and information on infectious and parasitic disease morbidity rates in the Republic of Tatarstan, presented by the Center of Hygiene and Epidemiology in the Republic of Tatarstan over 2015-2018 were utilized for analysis. Results and conclusions. The natural conditions of the Republic of Tatarstan are favorable for the circulation of pathogens of natural-focal diseases, which carriers are mammals (primarily small rodents) and birds, and vectors - blood-sucking arthropods: Ixodidae ticks, mosquitoes. The results of circulation monitoring of natural focal infection pathogens in the ambient environment made it possible to conclude that during the FIFA World Cup-2018, the epidemic risk of occurrence of natural-focal diseases would remain high. Considering the existing and forecasted internal risks, priorities were identified in the organization of preventive measures aimed at minimizing epidemiological risks in relation to natural-focal infections during the preparation and holding of the FIFA World Cup 2018. The chosen preventive strategy made it possible to prevent the infection with natural-focal infectious diseases among the population and ensure a stable epidemiological situation during the FIFA World Cup-2018.

Objective of the study is to investigate natural focality of Ixodidae tick borreliosis, granulocytic anaplasmosis, monocytic ehrli-chiosis in humans in the Republic of Tatarstan. Materials and methods. Utilized were the data from tick studies conducted between 2010–2015. Applying immune-enzymatic analysis, investigated were the blood sera from residents (donors) of Kazan and municipal districts of the Republic of Tatarstan for the presence of specific antibodies to borreliosis, ehrlichiosis, and anaplasmosis pathogens. Results and conclusions. For the first time ever, the data on spontaneous carriage of Ehrlichiosis pathogens in Ixodidae ticks have been obtained. The information received is an indicative of the active circulation of Borrelia, Ehrlichia and Anaplasma in the territory of the region and of necessity to expand the research on the “novel” for the Republic nosological forms of natural-focal infections.

Objective of the study is to evaluate the current state of epizootic activity of natural zoonotic foci, as the basis for the development of prophylactic measures aimed at prevention of natural-focal infections during mass events. Materials and methods. Utilized have been reports from the Center of Hygiene and Epidemiology in the Republic of Tatarstan, the data provided by Rospotrebnadzor Administration in the Republic of Tatarstan over the period of 2009-2014, and literature references. Results and conclusions. The most pressing natural-focal infectious diseases are hemorrhagic fever with renal syndrome, tick-borne borreliosis, and tick-borne viral encephalitis. Yersinioses, leptospiroses, and West Nile fever are rarely registered. Tularemia infections have not been reported within the past 20 years. The period of 2009-2013 is characterized by the decrease in the numbers of carriers and vectors of the diseases, as well as epizootic activity of natural foci, which came up to minimum values in 2013. Emerged since 2014 increment in the abundance rates of the carriers and later the vectors can lead to the increase in the incidence of natural-focal diseases. In the territory of the Republic, allocated are the spatial combination areas of natural foci of the diseases of various etiology with high risk of population exposure. Previous to conduction of mass events it is necessary to enhance the epizootiological surveillance in the natural foci, the results of which lay premises for the development of complex prophylactic activities.

The paper provides scientific substantiation for the deployment of auxiliary forces and facilities for the provision of sanitary-epidemiological welfare of the population under mass events with international participation. Identified are the tasks and key areas of the specialized anti-epidemic teams (SAET) of the Rospotrebnadzor activities during the preparation and carrying out of the XXVII World Summer Universiade in Kazan. Reviewed are the aspects of inter-agency cooperation between the network structures and mobile units of sanitary-epidemiological and medical-preventive bias during Universiade, 2013.

After the terrorist attack at theBostonMarathon, Federal and Republican executive bodies took increased security measures during the XXVII World Summer Universiade inKazan. Bodies and Organizations of the Federal Service for Surveillance on Consumer Rights Protection and Human Well-being (Rospotrebnadzor) were participants of all preparatory activities and directly provided security of the Student Games inKazan. This report analyzes the experience of providing radiation safety by Rospotrebnadzor experts at the stage of preparation for the Universiade. So far, Rospotrebnadzor organizations had no experience of providing radiation safety of such large-scale events. Analysis of the performed work with account for both positive and negative experiences is especially important in the context of preparations for the safety providing of the Olympic Winter Games inSochiin 2014.

In the second communication, the authors present and analyze in detail in chronological order all the activities performed in the course of providing radiation safety of the XXVII World Summer Universiade in Kazan. Special attention is given to assessing the effectiveness of the measures envisaged and implemented. Recommendations to improve the planning system have been developed, the list of measures ensuring radiation safety of the participants and guests to be held before and during large-scale events to ensure radiation safety was specified.

Put forward is a methodology for quantitative assessment of potential epidemic hazard (PEH) as regards mass events with international participation in terms of the relevant infectious diseases capable of (in compliance with IHR, 2005) inducing emergency situation of sanitary epidemiological character. It is established that PEH is an aggregate risk of infection importation by incoming contestants and visitors and of its dissemination across the mass even location. As a result of PEH level differentiation identified have been four following grades: high, medium, low and minimum. Calculated has been a rate of PEH for the XXVI Worldwide Summer Universiade in Kazan, 2013, exemplified by such infectious disease as cholera.

In consequence of epizootiological investigation, differentiated has been Kazan territory according to the potential epidemic hazard levels; determined is the abundance of carriers and vectors of natural-focal infection agents in and around the territory of the Summer Universiade-2013; substantiated is the scope of preventive measures (disinfection, deratization, desinsection), as well as their frequency and coverage area. Timely detection of the regions with expressed epizootic potential growth has made it possible to carry out prophylactic activities and reach an epidemic-hazard-lowering effect as regards particular territories of the natural and anthropourgic infectious disease foci. Further on, validated has been disinfection as part of specific prophylaxis and as a basic measure for elimination of risks of the population exposure to natural-focal infections directly during the mass event.

The paper discusses epidemiological environment of particular countries and parts of the world viewed as potential platforms for mass events with international participation. It is established that the most unfavorable in this respect are Asian countries, primarily South-Eastern Asia ones, and African ones, from where the majority of well-known pandemics and epidemics have originated. Specified are the factors which are significant for spread of infectious diseases that can trigger emergency situation of sanitary epidemiological character of international concern. They are tourism and migration, trade and economic affairs, natural and anthropogenic disasters. The concept - “potential epidemic hazard of mass events with international participation” - is defined. It is demonstrated that its structure comprises two levels: the natural background of endemic and imported as related to mass event region epidemiological hazards, and epidemiological hazards imposed by the event itself. Outlined is a step-by-step algorithm for assessment of “potential epidemic hazard” of mass events with international participation allowing for adjustment of measures for the provision of sanitary and epidemiological welfare of the population.