When predicting the epidemic situation in influenza, it is necessary to conduct a retrospective analysis that allows a correct assessment of the development of the epidemic process in a multi-year dynamics. The aim of the study was to assess the epidemic process and etiology of influenza and other acute respiratory viral infections in the long-term dynamics among different age groups of the population. The annual reports of the branch of FBUZ "Center of Hygiene and Epidemiology in the Sverdlovsk region" from 2015 to 2023 were analyzed. Laboratory diagnostic studies were carried out by PCR method (a total of 46952 patients were examined). It was found that influenza epidemics were polyethiologic and took place with simultaneous participation of influenza viruses A(H1N1)pdm09, A(H3N2) and B. In the long-term dynamics there was a tendency to instability of the epidemic process: in 2020-2021. observed a sharp decline in the circulation of influenza viruses to their complete absence. Against this background, the group of high risk of infection, which before this period were children under 6 years of age, was replaced by the older age group (15> years). Thus, the high proportion of viruses of non-influenza etiology, involved in the epidemic process, indicates the need for an operational approach to the development of tactics to protect the population from these viruses by means of nonspecific prophylaxis in epidemic seasons.

Analysis of etiological structure of acute respiratory infections and community-acquired pneumonia was performed in the Khabarovsk krai during COVID-19 pandemic period in 2020-2023. It was shown that utilization of polymerase chain reaction allowed to identify 48.8% of the diseases etiological agents in the conditions of abovementioned various infections. Presence of interference between influenza virus and SARS-CoV-2 etiological manifestations was detected. Active circulation of new coronavirus influenced seasonality of acute respiratory viral infections. Frequency of community acquired pneumonia caused by SARS-CoV-2 during early period of the virus circulation amounted over half of the examined cases. RT-PCR method allowed to detect 67.8% of viral and bacterial carriers among patients with community-acquired pneumonia.

The aim of the work was to evaluate the formation of population immunity to influenza in the pre- and post-epidemic periods in the long-term dynamics among the population of the Sverdlovsk region. Materials and methods: 2644 blood serum samples of donors living in the Sverdlovsk region were studied. The studies were carried out in the laboratory of FBUN FNIIVI "Virom" of Rospotrebnadzor by serologic method (RTGA) to determine protective antibody titers in blood sera. The data on the circulation of respiratory viruses were provided by the Center of Hygiene and Epidemiology in the Sverdlovsk region based on the results of the examination of patients with ARVI and influenza. Results: he lowest number of seropositive individuals with protective antibody titers (1≥40) to influenza A(HlNl) virus - 36.4-49.1% on the eve of the epidemic seasons 2015-2016, 2019-2020, 2020-2021, 2021-2022 - was detected, to influenza A(H3N2) virus - 38.0-50.0% in 2016-2017, 2018-2019, to influenza B virus - 40.4;45.1;34.5% in 2019-2020, 2020-2021, 2021-2022 respectively. At the end of the listed epidemic seasons, an increase in protective antibody titers was detected in accordance with the proportion of the above viruses. The exception was the seasons 2019-2020 and 2020-2021, when despite the minimum number of seropositive persons to influenza A(HlNl) virus, their number at the end of the season practically did not change (p>0.05), and PCR studies did not reveal the circulation of this virus in the population. This fact can be explained by the suppression of the mentioned virus circulating at this time by the epidemic variant of Wuhan strain SARS-CoV-2. Discussion: It is hypothesized that when the level of population immunity (PI) to influenza viruses was lowest before an epidemic upsurge caused by a particular influenza virus, the incidence rates of this virus in the population became higher when the epidemic occurred. Consequently, the immune layer of the population to circulating influenza viruses was in correlation with the activity of the epidemic process. Conclusion: the determination of the immune layer continues to be a tool for predicting the epidemic process in influenza. The conducted research proves its relevance.

Over the past few years, the number of cases of HFMD diseases associated with Coxsackievirus A5 (CVA5) infection has increased worldwide. The detection rate of this virus has become comparable to the currently dominant pathogens: CVA6, CVA16, CVA10 and Enterovirus A71. The dynamics of CVA5 circulation in the European part and eastern regions of Russia in the period 2013-2023 is characterized. The genetic diversity and phylogenetic relationships of strains identified in the Russian Federation and other countries are studied. The virus was detected annually, with the exception of 2020, detection peaks were recorded in 2018 and 2023. The proportion of CVA5 in the structure of etiological agents of enterovirus infection averaged 4.27%, in the structure of identified Enterovirus A viruses – 7.25%. CVA5 infection was more often manifested in the form of acute respiratory disease 33.05%, herpangina – 22.88%, HFMD – 16.95%. The Russian CVA5 strains were characterized by genetic heterogeneity, manifested by the simultaneous circulation of viruses belonging to different genotypes and genovariants.

Introduction. The annual increase in the incidence of enterovirus infection (EVI) in the population of the Far East and Eastern Siberia determines the need for constant epidemiological surveillance of EVI using molecular typing of enteroviruses. Aims. Analyze EVI incidence and establish the types of enteroviruses circulating in the territories of the Far Eastern and Siberian federal districts of the Russian Federation in 2023. Make a short-term prognosis of the incidence of EVI for 2024. Materials and Methods. To analyze EVI incidence, statistical reports from Rospotrebnadzor authorities in the Far Eastern and Siberian federal districts were used. Determination of enterovirus types was carried out using sequencing of the VP1 genome fragment. Results. In 2023, a significant excess of the long-term average incidence rate of EVI was noted in 8 of the 16 analyzed territories of the Far East- ern and Siberian federal districts. The main clinical forms of EVI were herpangina and exanthema forms. Among the identified types of enteroviruses in 2023, coxsackievirus A6 predominated. Phylogenetic analysis revealed the circulation of a new variant of the eC2 genotype of the ECHO30. The calculation of prognostic indicators showed that an increase in EVI incidence in 2024 is expected in five analyzed territories. Conclusion. The manifestations of the EVI epidemic process in the territories of the Far Eastern and Siberian federal districts in 2023 were influenced by the active circulation of the coxsackievirus A6 and the emergence of a new ECHO30 genovariant. In the territories with high EVI incidence rates predicted for 2024, attention should be paid to the timely organization of epidemic control measures.

An epidemiological and molecular genetic analysis of norovirus outbreaks in the Amur oblast during 2024 is presented. Etiological agents that caused outbreaks were identified – norovirus genovariants GII.4_Sydney [P16] and GII.7 [P7]. Non-compliance with anti-epidemic measures, violation of sanitary legislation in institutions kitchens, presence of sick kitchen staff at the workplace, untimely notification of the Rospotrebnadzor regional offices about emergence of outbreaks among students as well as late isolation of the infected people facilitated emergence and spread of the infection.

A comparative analysis of HIV-1 and hepatitis C virus (HCV) among patients with monoinfection as well a co-infection residing in constituent entities of the Far Eastern Federal district. It was established that HIV-1 sub-subtype A1 (84.7%) was detected more frequently among people living with HIV (PLWH) compared to individuals co-infected with HIV-1 and HCV (62.8%). Among the latter, prevalence of HIV-1 recombinant forms was 2.7 times higher (32.6%) compared to HIV monoinfected people (11.9%). HCV subtype 3a was identified more frequently among patients co-infected with HIV-1 and HCV (49.1%). HCV 1b (40.6%), 2 (5.7%) and 1a (4.7%) genovariants were less common. However, in general, there were practically no differences in the distribution of HCV genotypes be- tween examined groups. In addition to evaluating general patterns of pathogens genetic variants circulation, it is advisable to estimate peculiarities of their distribution depending on gender and presence of co-infection.

HIV-infection remains a pressing issue in both Russia and Far Eastern Federal district. Current research was conducted to evaluate HIV epidemic tendencies in the Far Eastern Federal district. Cumulative number of HIV-infected has reached 56 799 people in early January 2024. HIV screening coverage of district population has reached 33.04%. HIV-infection incidence rate equaled 34.0 per 100 000 population, prevalence rate – 451.2 per 100 000 population in 2023. Rate of men among newly infected people with HIV remained high. Heterosexual route of transmission was prevailing. A total number of 83.5% of people living with HIV were registered for regular medical check-ups and 72.1% of them received antiretroviral therapy.

Preservation of younger generation health is an up-to date issue and a matter of primary importance since it determines the future of the country, preservation of the nation's gene pool as well as scientific and economic potential of the society. In order to evaluate the levels of awareness regarding HIV-infection and viral hepatitis among Magadan oblast youth an anonymous survey was performed by the means of Internet telecommunication system for planning awareness-raising work. The survey involved 417 youth respondents whose average age was 19.54 years. Overall levels of awareness among youth was relatively satisfactory however there were false claims and myths regarding routes of transmission as well as certain stigmatizing behavior towards people living with these infections. The results of the study can be used for planing educational work regarding youth health preservation and prevention of HIV infection and viral hepatitis spread.

Current article presents results of research on immune structure of the Khabarovsk krai population against infectious agents of parasitic diseases in 2023. Seropositive individuals were detected among examined relatively healthy people who had immunoglobulins of G class against following pathogens antigens: Echinococcus granulosus (22.17%; 95% CI: 19.43-24.91%), Trichinella spp. (5.88%; 95% CI: 4.23-7.53%), Toxocara canis (22.65%; 95% CI: 19.91-25.39%), Clonorchis sinensis (1.5%); 95% CI: 0.63-2.29%), Opisthorchis felineus (6.93%; 95% CI: 5.14-8.72%), Anisakis spp. (25.91%; 95% CI: 22.96-28.86%), Ascaris lumbricoides (38.0%; 95% CI: 34.93-41.07%), Taenia solium (0.55%); (95% CI: 0-1.1%), Lamblia intestinalis (11.72%; 95% CI: 9.64-13.8%). The results of the research indicate a contact between region population and causative agents of parasitic invasions and confirm importance of optimization of epidemiological surveillance diagnostic system over parasitic diseases.

Currently, there is an increase in the number of cases of dengue fever imported into the territory of the Russian Federation, which is associated with the development of international cooperation and tourism. The article presents a brief literature review and analysis of a clinical case of classical dengue fever in a patient returning from a trip to Thailand. The patient had symptoms characteristic of classical dengue fever: two-wave fever, intoxication, severe headache, exanthema, itchy skin, enanthema, arthralgia, leukopenia and thrombocytopenia. The diagnosis was confirmed by PCR.

A clinical case of a rare, severe and difficult to diagnose iatrogenic lesion of the central nervous system - osmotic demyelinating syndrome (ODS) and a brief review of the literature is presented. Osmotic demyelinating syndrome with damage to the pons of the brain developed in a 36-year-old woman, HIV-infected, suffering from alcoholism with polyvisceropathy, drug addiction, chronic hepatitis of high activity and chronic pancreatitis in the acute stage. The condition was accompanied by moderate hyponatremia. This clinical observation will be of interest to doctors of various specialties, will expand the understanding of the clinical manifestations and treatment of ODS and will allow for the prevention or timely diagnosis of such a rare pathology.