Epidemiological characteristics of Epstein–Barr virus infection

Introduction. The Epstein–Barr virus (EBV) is one of the most common pathogens — it infects 90% of the world’s population. However, specific characteristics of the EBV infection epidemic process remain unidentified. The previous studies focusing on assessment of incidence rates for infectious mononucleosis (IM) tend to ignore the serological status of the population.The aim of the study was to identify epidemiological characteristics and assess the prevalence of serological markers for EBV infection for further epidemic control measures development.Materials and methods. In Moscow, the thorough analysis was performed using the data on IM incidence (Form 2 "Data on Infectious and Parasitic Diseases") and test results for 138,232 people checked for presence of VCA IgG, EBNA IgG, VCA IgM, EA IgG, and EBV DNA in their blood and saliva in 2011–2020.Results. The periodic pattern of IM incidence was discovered, demonstrating the repetitive peaks every 9 to 11 years and a strong direct correlative relationship with detection rates for active EBV infection markers. The intra-annual dynamics of IM incidence is characterized by a seasonal upswing during cold seasons of the year, reaching its peaks in October, November, or February and associated with a marked decrease in the VCA IgG and EBNA IgG seroprevalence. Children within the 1 to 17-year age range are groups at risk for acquiring primary infection, demonstrating significantly lower detection rates for chronic EBV infection (VCA IgG and EBNA IgG) markers and higher rates for VCA IgM and EBV DNA markers in blood compared to adults. The contribution of adult population to the epidemic process is formed through reactivation of chronic infection, which is observed primarily among women.Conclusion. The identified characteristics are essential for comprehensive understanding of the EBV infection epidemic process and can be used for developing preventive and anti-epidemic measures.

Epidemiological Community and Differences of Transmissive Infections in Astrakhan Region

Relevance. The territory of the Astrakhan region hosts natural foci of severe infections of arbovirus etiology – Crimean-Congo hemorrhagic fever (CCHF) and Astrakhan fever (spotted fever resembling the Mediterranean spotted fever, Astrakhan spotted fever (ASF). The long-term average incidence of CCHF and ASF in the Astrakhan region is to 11 and 135 times higher, respectively, than the average incidence in the Russian Federation. Aims. To present, based on epidemiological data, a comparative characterization of transmissible infections of CCHF and ASF in the Astrakhan region. Materials & Methods. The main method of the study was epidemiological. The data for 2000−2016 of primary medical documentation Ф.058/у «Emergency notification of infectious disease, food, acute occupational poisoning, unusual reaction to vaccination», federal statistical observation Ф. 2 «Information on infectious and parasitic diseases», Ф. 357/у «Epidemiological examination card of infectious disease focus», Ф. .003/у «Medical card of inpatient patient», presented by Center of hygiene and epidemiology in Astrakhan region. For retrospective epidemiological analysis, we studied the absolute and intensive morbidity indicators (per 100 ths population), by age, professional groups, and among the urban and rural population. Based on the average long-term morbidity indicators of the population, a mapping of the territory of the Astrakhan region was carried out. The influence of natural and climatic conditions on the epidemic process of CCHF and ASF was assessed by meteorological data (amount of precipitation, air temperature, etc.). Materials of long-term observation over 11 districts of Astrakhan region and Astrakhan city were analyzed, including data on the spread of Ixodid ticks, population contact with them (according to the attendance of people to treatment-and-prophylactic organizations of the region). Statistical data processing was carried out using the method of straight-line alignment of dynamic series of morbidity indicators, calculation of the average annual rate of decrease/increase. Correlation analysis was used to assess the direction and strength of the relationship between the indicators, and quantitative dependence between epidemic process characteristics. Differences between the indicators were considered to be reliable if p < 0.05. Results. During the analyzed period 151 cases of CCHF and 3951 cases of ASF were identified. By 2016. CCHF was registered in all 11 districts of the region and the area of foci covered 44,000 km2 and 44,100 km2, respectively. There are no differences significantly affecting the epidemic process of CCHF and ASF, so preventive measures are mainly aimed at controlling the vectors of the pathogens of these infections. The comprehensive study of the territory of Astrakhan region carried out in 2000–2016 revealed expansion of CCHF and ASF areal of disease (by 11.8% and 23.4% respectively) and determined the territories with the highest risk of infection, which allowed to increase and redistribute the volumes of acaricide treatments of the territories with the highest infection risk and ensure the decrease of CCHF and ASF morbidity rates. Conclusion. As a result of the comprehensive study conducted in 2000–2016 in the territory of Astrakhan region, the expansion of CCHF and ASF areal of disease was revealed (by 11.8% and 23.4% respectively) and the areas of highest infection risk were identified, which allowed to increase and redistribute the volume of acaricide treatments of the areas of highest infection risk and ensure the reduction of CCHF and ASF morbidity.

Characteristic of herd immunity among the population of Stavropol region amid the COVID-19 epidemic

Introduction. The first pandemic in the 21st century, caused by the pathogenic representative of the coronavirus SARS-CoV-2, began in the Chinese city of Wuhan, where the first outbreak of coronavirus pneumonia was recorded in December 2019. The disease spread so quickly around the world that already on February 11, 2020, WHO was forced to declare a pandemic of the “coronavirus disease 2019” COVID-19. The first case of COVID-19 in the Stavropol Territory was registered on March 20, 2020, and three weeks later, starting from the 15th week of the year, a steady increase in the incidence began, which lasted until the 52nd week. During the study period, the incidence increased from 21.1 to 28.3 per hundred thousand of the population. Growth 1.3 times.Purpose: to determine the dynamics of population immunity among the population of the Stavropol Territory in 2020-2021. during the period of an epidemic increase in the incidence of COVID-19. Materials and methods. The SARS-CoV-2 study was carried out according to a unified methodology within the framework of the program for assessing the population immunity of the population of the Russian Federation, developed by Rospotrebnadzor with the participation of the St. Pasteur. In total, 2688 people were examined, divided into 7 age groups. In the examined individuals, the level of specific IgG to the SARS-CoV-2 nucleocapsid was determined by the enzyme immunoassay.Results. The level of seroprevalence among residents of the Stavropol Territory was 9.8%. The largest proportion of seropositive individuals was found in the age groups 1-6 and 7-13 years old (19.2% and 19.7%, respectively). Seroprevalence had no gender differences and ranged from 9.3% to 10.8%. When assessing the distribution of the proportion of seropositive persons in different geographic territories of the region, it was found that the maximum proportion was found in the Kochubeevsky district (23.1%), the minimum in Kislovodsk (7.7%). Among convalescents, the content of specific antibodies to SARS-CoV-2 was noted in 73.3%, which is 7.8 times higher than the average population level. When conducting seromonitoring in the 2nd half of 2020, a 10-fold increase in seroprevalence was recorded, accompanied by a decrease in incidence from the 5th week of 2021. Among asymptomatic volunteers in whom SARS-CoV-2 RNA was detected by the polymerase chain reaction, antibody titers to viruses were found in 78.6%, which corresponds to the seroprevalence of convalescents. The proportion of seropositive persons among those who have come into contact with COVID-19 patients was 16.4%, (1.8 times higher than the average for the population). Out of 262 seroprevalent volunteers, the asymptomatic form of SARS-CoV-2 was detected in 92% of the examined, which indicates a significant role of the number of asymptomatic forms of infection in the epidemic process of COVID-19.Conclusion. The results of assessing the population immunity of the population of the Stavropol Territory indicate that it has not yet reached the threshold level at which a decrease in the intensity of the COVID-19 epidemic process can be expected.

Influence of the ways of spreading influenza epidemics across the territory Russia on the peculiarities of the epidemic process in various Federal districts

Aims. Show the ways of spreading influenza epidemics across the territory of Russia over a long period (1968–2019) and their influence on the incidence of influenza and ARVI in total and separately influenza A (H1N1), A (H3N2) and B in the Federal Districts in the period from 2009 to 2019.Materials and methods. The analysis of influenza epidemics was carried out according to the computer database of the National center for influenza.Results. A retrospective analysis of influenza epidemics shows the absence of inter-epidemic seasons after 1986, the increase in epidemics of mixed etiology and different routes of entry and spread of influenza viruses in Russia. During the circulation of the influenza A (H1N1)pdm09 virus, influenza epidemics were mainly of mixed etiology. The main causative agents of epidemics entered the territory of Russia more often from the west and in both ways, and from the west and from the east. In the next season, the main pathogen changed, and the path of the virus circulating in the previous season also changed. Influenza viruses of different types A and B usually diverged in time. Influenza viruses of the same type A, but of different subtypes, usually spread in different directions, with one of them having a limited distribution in the districts. The tendency of greater intensity of the epidemic process in the districts involved in the epidemic first is shown.Conclusions. 2009 to 2019 the incidence was higher in the Northwestern and Ural districts of the European part of Russia. One of the reasons for the high morbidity in these districts is the predominance of the western route of influenza viruses entering the territory of Russia and the high intensity of the epidemic process in the districts that were the first to be involved in the epidemic.

The approximation of an isolated epidemic process wave using a combination of exponents

The most commonly used methods for the medium- and long-term forecasting of epidemic processes are based on the classical SIR (susceptible – infected – recovered) model and its numerous modifications. In this approach, the dynamics of the epidemic is approximated using the solutions of differential or discrete equations. The forecasting methods based on the approximation of data by functions of a given class are usually focused on obtaining a short-term forecast. They are not used for the long-term forecasts of epidemic processes due to their insufficient efficiency for forecasting nonstationary processes. In this paper, we formulated a hypothesis that the primary waves of the COVID-19 pandemic, which took place in a number of European countries, including the Republic of Belarus, in the spring-summer of 2020 are isolated and therefore can be regarded as processes close to stationary. On the basis of this hypothesis, a method of approximating isolated epidemic process waves by means of generalized logistic functions with an increased number of exponents was proposed. The developed approach was applied to predict the number of infected people in the Republic of Belarus for the period until August 2020 based on data from the beginning of the epidemic until June 12, 2020.

Comparative Cohort Epidemiological Study of Collective Immunity against New Coronavirus Infection among Different Groups of Military Personnel

Background. The need to study the population immunity to the SARS-CoV-2 virus is due to the intensive spread of COVID-19 and the implementation of immunoprophylaxis of this infection. The identification of the features of the formation of immunoresistance in organized military collectives will allow us to predict the development of the epidemic situation, including among comparable population groups. Aims the study of population immunity to the SARS-CoV-2 virus in the context of the COVID-19 pandemic against the background of specific immunoprophylaxis in organized military collectives. Methods. According to epidemiological indications, an epidemiological study of collective immunity to the SARS-CoV-2 virus was conducted against the background of vaccination among cadets of military educational organizations. The study involved 497 people, divided into groups by epidemiological and vaccination history for COVID-19, blood groups and Rh factor. The assessment of the immunity intensity was carried out by the levels of class G immunoglobulins (IgG) to SARS-CoV-2 in the blood serum by the method of solid-phase enzyme immunoassay. Results. Seroprevalence in the total sample was 92.6%. The highest rates were observed among vaccinated patients: those who were not ill and vaccinated 99.0 0.7%, those who were ill and vaccinated-100% (mean geometric antibody titers 1:2234 and 1:4399). Among the ill, unvaccinated individuals, the seroprevalence index was 84.5 3.2% (1:220). Among those who were not ill, not vaccinated 8.2 3.1% (1:113), which may indicate a hidden course of the epidemic process in the team. A negative immune response was more common (tSt = 2.01; p 0.05) in individuals A(II)Rh+ blood group. The highest proportion of maximum antibody titers (1:32001:6400) was determined in AB(IV) individuals. Rh-blood groups (tSt=2.21; p 0.05). Conclusions. For the first time, the formation of combined immunity with the highest concentrations of specific antibodies was revealed in patients who have been ill and vaccinated has been revealed, which allows us to recommend vaccination to those who have suffered from COVID-19. The emergence of post-infectious immunity in organized groups with a latent epidemic process has been established. The relationship between the intensity of immunity with blood groups and the Rh factor was found.

The COVID-19 pandemic: an analysis of the epidemic situation and the restructuring of medical education (according to the Republic оf Mordovia)

Возникновение нового варианта вируса и эпидемический потенциал, проявленный возбудителем COVID-19, поставили перед специалистами здравоохранения задачи, связанные с быстрой разработкой диагностики и профилактики новой инфекции, а также тактики оказания медицинской помощи больным. Активное распространение коронавирусной инфекции заставило активно вносить изменения в систему медицинского образования. Целью данной работы был анализ эпидемиологической ситуации по COVID-19 в Республике Мордовия для понимания особенностей развития эпидемического процесса и составления его прогноза, а также рассмотрения перестройки образовательного процесса в условиях пандемии. Проведен ретроспективный анализ эпидемиологической ситуации по заболеваемости COVID-19 в Республике Мордовия, проанализирована эффективность реализации профилактических и противоэпидемических мероприятий, приведены данные по динамике заболеваемости, выздоровлению и летальности пациентов. Изучены элементы перестройки образовательного процесса. Проанализирована эпидемиологическая ситуация в сравнении с некоторыми регионами РФ, изучены данные по проведению вакцинации, по динамике коечного фонда за период пандемии. Вероятность смерти от коронавируса COVID-19 в Республике Мордовия аналогична мировым показателям. Можно предположить, что дистанционное обучение займет одну из лидирующих позиций в высшей школе. Благополучная ситуация в Республике Мордовия с заболеваемостью и летальностью от новой коронавирусной инфекции складывалась благодаря реализации научно обоснованной стратегии опережающего реагирования – на основе постоянной оценки масштабов распространения новой коронавирусной инфекции, анализа тенденций эпидемического процесса, моделирования развития эпидемической ситуации и проводимых превентивных мероприятий. Непосредственное участие преподавателей университета в лечебной работе, использование их опыта и знаний в решении практических задач будут способствовать повышению качества медицинской помощи и развитию системы здравоохранения Республики Мордовия не только в условиях пандемии COVID-19, но и в дальнейшем. The emergence of a new variant of the virus and the epidemic potential manifested by the causative agent of COVID-19 have set health professionals tasks related to the rapid development of diagnostics and prevention of a new infection, as well as tactics for providing medical care to patients. The active spread of coronavirus infection has forced active changes to the system of medical education. The goal is to analyze the epidemiological situation of COVID-19 in the Republic of Mordovia in order to understand the development of the epidemic process and make a forecast, consideration of the restructuring of the educational process in the context of a pandemic. In this article, a retrospective analysis of the epidemiological situation on the incidence of COVID-19 in the Republic of Mordovia is carried out, the effectiveness of the implementation of preventive and anti-epidemic measures is analyzed, data on the dynamics of morbidity, recovery and mortality of patients are presented. The elements of the restructuring of the educational process are studied. The epidemiological situation was analyzed in comparison with some regions of the Russian Federation, data on vaccination, on the dynamics of the bed fund during the pandemic period were studied. The probability of death from the COVID-19 coronavirus in the Republic of Mordovia is similar to the indicators around the world. It can be assumed that distance learning will take one of the leading positions in the process of studying in higher education. A favorable situation in the Republic of Mordovia with morbidity and mortality from a new coronavirus infection was formed positive to the implementation of a scientifically grounded strategy of proactive response – based on a constant assessment of the scale of the spread of a new coronavirus infection, analysis of trends in the epidemic process, modeling the development of the epidemic situation and ongoing preventive measures. The direct participation of university teachers in medical work, the use of their experience and knowledge in solving practical problems will contribute to improving the quality of medical care and the development of the healthcare system of the Republic of Mordovia not only in the conditions of the COVID-19 pandemic, but also in the future.

Simulation and forecasting of the influenza epidemic process using seasonal autoregressive integrated moving average model

Today's global COVID-19 pandemic has affected the spread of influenza. COVID-19 and influenza are respiratory infections and have several similar symptoms. They are, however, caused by various viruses; there are also some differences in the categories of people most at risk of severe forms of these diseases. The strategies for their treatment are also different. Mathematical modeling is an effective tool for controlling the epidemic process of influenza in specified territories. The results of modeling and forecasts obtained with the help of simulation models make it possible to develop timely justified anti-epidemic measures to reduce the dynamics of the incidence of influenza. The study aims to develop a seasonal autoregressive integrated moving average (SARIMA) model for influenza epidemic process simulation and to investigate the experimental results of the simulation. The work is targeted at the influenza epidemic process and its dynamic in the territory of Ukraine. The subjects of the research are methods and models of epidemic process simulation, which include machine learning methods, in particular the SARIMA model. To achieve the aim of the research, we have used methods of forecasting and have built the influenza epidemic process SARIMA model. Because of experiments with the developed model, the predictive dynamics of the epidemic process of influenza for 10 weeks were obtained. Such a forecast can be used by persons making decisions on the implementation of anti-epidemic and deterrent measures if the forecast exceeds the epidemic thresholds of morbidity. Conclusions. The paper describes experimental research on the application of the SARIMA model to the epidemic process of influenza simulation. Models have been verified by influenza morbidity in the Kharkiv region (Ukraine) in epidemic seasons for the time ranges as follows: 2017-18, 2018-19, 2019-20, and 2020-21. Data were provided by the Kharkiv Regional Centers for Disease Control and Prevention of the Ministry of Health of Ukraine. The forecasting results show a downward trend in the dynamics of the epidemic process of influenza in the Kharkiv region. It is due to the introduction of anti-epidemic measures aimed at combating COVID-19. Activities such as wearing masks, social distancing, and lockdown also contribute to reducing seasonal influenza epidemics.

Epidemiological and etiological aspects of enterovirus infection in Russia and Vietnam

The epidemic situation and etiological factors of enterovirus infection in Russia and Vietnam were analysed and compared. The identified strains of enteroviruses of 47 types, which circulated in Russia in 2018–2019, belonged to different species: Enterovirus species A (CV-A2, CV-A4, CV-A6, CV-A8, CV-A10, CV-A16, EV-A71), as well as Enterovirus species B and Enterovirus species C. The strains isolated from 87 children from southern Vietnam hospitalised in 2018–2019 into infectious hospitals while having enterovirus infection with exanthema were also studied. All identified strains were represented by Enterovirus species A: EV-A71 — 59 strains, CV-A10 — 20 strains, CV-A16 — 5 strains, CV-A6 — two strains and CV-A2 — one strain. Out of 59 viruses EV-A71, 53 strains belonged to genotype C4 and 6 strains belonged to genotype B5. The sequences of EV-A71 strains of genotype C4 from South Vietnam formed a monophyletic cluster with the sequences of EV-A71 viruses which circulated during 2016–2018 in different provinces of China, and they were very close to EV-A71 strains of the same genotype from the Yunnan Province. These strains were genetically different from Russian viruses and Vietnamese viruses identified in the years 2003–2005 and 2011– 2012. Most of the cases of enterovirus infection from southern Vietnam (78%) caused by EV-A71 virus of genotype C4 were reported in three provinces located in southern Vietnam in the Mekong Delta. The epidemic process and the etiology of enterovirus infection in Russia and Vietnam have common features. At the same time, the epidemic situation in these countries is not the same. The incidence of enterovirus infection is influenced by geographic, climatic, economic and demographic factors that differ in two countries. In the majority of territories of Russia, the climate is temperate or cold, seasonal rises in the incidence rates of enterovirus infection usually occur in the summer, when people go on vacation, spend a lot of time outdoors and swim in open reservoirs. In Vietnam, a constant high-level temperature, a high population density and a large proportion of children determine the higher incidence of enterovirus infection, especially in the southern provinces of Vietnam, compared to Russia. The fact that more than 20% of the Vietnamese population lives in the Mekong Delta, which is the largest river in Indochina, has a significant impact on the epidemic process of enterovirus infection in South Vietnam. The Mekong River which flows through China, Laos, Thailand, Cambodia and Vietnam, and carries huge streams of water, including rainstorm waters and sewages, from all of these countries into the southern provinces of Vietnam, which have the highest incidence rates of enterovirus infection in the country. The results of the research underline the importance of active epidemiological and virological surveillance of enterovirus infection, which plays the key role in informing the public health authorities about the changes in the epidemic situation in order to take appropriate measures and develop the prevention strategies. The goal of anti-epidemic and preventive measures is to reduce the incidence of enterovirus infection and the economic burden of this infection for Russia and Vietnam.