Relevance. During the period of long–term measles vaccination in Russia, the age of those who were vaccinated with live measles vaccine changed several times – from 9 to 15-18 months, until scientific research proved the optimal age of 12 months. During the period of measles elimination, when population immunity is formed mainly through immunization, and the artificial active immunity of mothers protects children of the first year of life for a shorter period of time than natural active immunity, the incidence of this infection in children under 1 year of age is of particular importance for managing the epidemic process of measles. The aim of this study is to assess the importance of measles in the epidemic process of children under the age of 1 year during the elimination of infection, the effectiveness of the current measles vaccination regimen.
Materials and methods. The measles incidence in children under 1 year of age was analyzed in absolute and relative terms for the period from 2010 to 2024. For more u For a more in-depth analysis, the years of the increase in the incidence of 2012, 2014, 2019, 2023 and 2024 were selected, when the patterns of involvement of this analyzed group in the epidemic process of measles were most pronounced. The Pearson coefficient was used to determine the correlation.
Results and discussions. The configuration of the measles incidence curve in children in the first year of life completely coincides with the dynamics of measles incidence in the general population, and a strong positive correlation (r=+0.99) confirmed the dependence of the incidence of the analyzed age group on the overall incidence. Further in-depth analysis showed that children under the age of 1 are not the leading group at high risk of infection, but rather passively participate in the epidemic process, becoming involved in the process with an increasing number of sources of infection. Thus, the proportion of sick children during the years of the rise in morbidity ranged from 7.77% to 15.87%, but even in the year of the maximum increase in the overall incidence, the but at the same time, even in the year of the maximum increase in the overall incidence recorded in 2024, when the total number of cases exceeded 22 thousand people, the analyzed indicator did not exceed 9.69%. Children aged 6-11 months were more likely to get sick, accounting for an average of 75.98%, while the proportion of children with measles in the first five months averaged 24.02%. The structure of measles cases was dominated by unvaccinated individuals. During the years of the rise in the incidence of 2012, 2014, 2019, 2023, 2024, the proportion of the unvaccinated accounted for respectively 77,0%, 75,2%, 84,4%, 88,8%, 89,5%. Among them, children of the first year of life accounted for a small percentage – only 20,6%, 14,9%, 9,4%, 8,7% and 10.7%.
Conclusion. The results of the analysis of the incidence of children under one year of age confirmed the validity of vaccination tactics at 12 months and at 6 years of age in our country. The incidence of measles in children under the age of vaccination directly depends on the vaccination against measles in their immediate environment, therefore it is very important to maintain population immunity at a level of at least 95.0%. At the moment, there is no reason to change the scheme, which does not exclude its change in the event of new vaccines or changes in the epidemic situation for measles.

Purulent diseases of skin and soft tissues occupy the leading place among surgical infections in terms of frequency of occurrence and possible complications. The most significant etiological agents in surgical infections of soft tissues are group A streptococci (SGA), however, there are known cases of severe invasive infections caused by group B, C, G streptococci and pneumococci.
Aim. To estimate the frequency and identify the features of soft tissue streptococcal infection in patients of the purulent-surgical department of a multidisciplinary hospital in Moscow.
Materials and Methods. We conducted an epidemiological observational descriptive continuous retrospective study based on the analysis of data from case histories of purulent surgery patients with isolation of Streptococcus monocultures obtained from the unified medical information and analytical system (EMIAS) of a multidisciplinary hospital in Moscow for 2020–2022. Establishment of a case of invasive infection was based on the criteria proposed by the US Centers for Disease Control and Prevention (CDC), according to which a case of invasive infection is defined by the isolation of the pathogen from the sterile in normal conditions environment of the organism and laboratory confirmation of infection with clinical signs of invasive disease. Statistical processing and analysis of the study results were performed using Microsoft Excel 2010 and IBM SPSS Statistics 22.
Results. During the study period, 235 cases of skin and soft tissue infections with isolation of Streptococcus monocultures were detected in the department of purulent surgery of a multidisciplinary hospital. The most frequent diagnoses were abscesses – 109 (37,59%), phlegmons – 61 (21,03%), infected wounds – 30 (10,34%), purulent destructive arthritis – 12 (4,14%). The comorbidities identified were hypertension (HD) 21.45%, diabetes mellitus (DM) 19.8%, coronary heart disease (CHD) 12.54%, and hepatitis 4.97%. The age median of all patients was 47 (IQR=20) years. On average, patients spent 9 days in hospital. In 9.79% of cases, the treatment of patients was rather long (>21 days). Among the monocultures of streptococci isolated from patients, S. pyogenes (40.78%), S. agalactiae (22.75%), S. anginosus (13.33%) and S. constellatus (6.27%) were predominant. A total of 32 (13.62%) cases of invasive soft tissue infection were identified during the study period, of which 16 (50.0%) were associated with S. agalactiae monocultures, 9 (28.13%) with S. pyogenes, and the remaining 7 (21.88%) with other streptococcal species. Male patients (87.5%) predominated in the sex and age structure. During the analysed period, mortality in the invasive form of infection was 6.25%. According to the ROC-analysis, the development of the invasive form of infection was predicted in patients aged 52 years and older. The comorbidities most closely associated with the invasive form of infection were diabetes mellitus DM (OR = 4.2), GB (OR = 2.7), CHD (OR = 4.8) and gastrointestinal inflammatory disease (OR = 14.3).
Conclusion. The study demonstrated a wide prevalence of soft tissue streptococcal infection in the department of purulent surgery of a multidisciplinary hospital with the predominance of S. pyogenes, S. agalactiae, S. anginosus and S. constellatus in the etiological structure and showed the possibility of developing invasive forms of the disease associated not only with group A streptococci, but also with other species of streptococci.

Relevance. Mitis group streptococci (SMG) include 9 species of streptococci most frequently isolated from patients, including Streptococcus oralis and Streptococcus pneumoniae. The study of SMG shows not only differences but also overlaps in the genes encoding pathogenicity factors of S. pneumoniae and S. oralis. Earlier it was shown that antigens from S. pneumoniae serotype 6B induced cross-protective effect against virulent strains of S. pneumoniae. It was found that the experimental surface protein-containing fraction with molecular weight 30-100 kDa (PCF) from S. oralis has protective activity, stimulates in mice indicators of innate and adaptive immunity.
Objective: to carry out a comparative analysis of pathogenicity factors of S. oralis and S. pneumoniae strains and protective activity of surface protein-containing antigens isolated from them.
Materials and methods. The strains of S. oralis and S. pneumoniae serotype 6B Nos. 3353 and 1121 of different virulence were used. Experimental protein-containing antigens, in particular, PCF, were prepared from these strains. The protective activity of the obtained PCFs was evaluated in active protection experiments during intraperitoneal immunization and infection of BALB/c mice. Mass spectrometric study of PCF was carried out using UniProtKB database, taxon S. pneumoniae serotype 4 (strain ATCC BAA-334 / TIGR4.) Statistical processing of the results was carried out using parametric and nonparametric methods of comparison (p<0.05).
Results and discussion. PCF from S. oralis has cross-species protective activity against virulent strains of S. pneumoniae of different serotypes, while PCF from S. pneumoniae strain 6B No. 3353 protects only against a virulent strain of the homologous serotype. Comparative analysis of genes encoding pathogenicity factors revealed differences: only in S. oralis genes encoding the synthesis of proteins promoting adhesion and biofilm formation (SspA, GtfD RlrA), and in S. pneumoniae strains - pore-forming toxin (Ply) and choline-binding protein (LytA) were identified. In the proteomic analysis of S. oralis and S. pneumoniae 6B No. 3353 PCFs, out of 673 identified proteins, 57 common proteins of most interest and 21 and 35 unique proteins, respectively, were selected for each PCF: in S. oralis PCFs, adhesion proteins were identified, as well as proteins related to metabolic systems and mediating the development of the infection process, while in S. pneumoniae PCFs, adhesion proteins were predominant those indirectly involved in the development of the infectious process, while the S. pneumoniae PCF is dominated by proteins related to the main pathogenicity factors.
Conclusions. The surface protein-containing fraction 30 -100 kDa (PCF) isolated from a weakly virulent strain of S. oralis, belonging to the Mitis group streptococci, has interspecies protective activity against strains of closely related species - S. pneumoniae of different serotypes. PCF is capable of both preventing adhesion and colonization of pneumococcus and possibly playing the role of a natural adjuvant. In addition, it may be of interest to determine the protective effect of this antigen against other closely related SMG representatives. Both different and common genes encoding the synthesis of the main pneumococcal pathogenicity factors were identified in the strains, and unique proteins for each of them were determined by proteomic analysis of PCF.

Relevance. The study of natural foci of infections transmitted by ticks is an integral part of the study of the clinical and epidemiological characteristics of this group of diseases and their manifestations in various endemic areas.
The aim of this work was to obtain up-to-date information regarding the spread of the most epidemically significant pathogens of bacterial infections carried by ticks in natural foci of the Baikal region using molecular analysis methods.
Materials & Methods. Analyzed infections of I. persulcatus with pathogens transmitted by ticks (Borrelia spp., Ehrlichia spp., Anaplasma spp.) in natural foci in the Baikal region of Russia with determination of the species diversity of Borrelia (B. afzelii, B. garinii, B. miyamotoi) in the studied material. The study used RT-PCR for detection.
Results. The total infection of ticks with Borrelia - 45.3%, Ehrlichia - 16.0% and Anaplasma - 15.9%. The study shown the unevenness of infection of ticks by pathogens in the study area. The dominant species of Borrelia was B. garinii - 44.0% of cases, in second place was B. miyamotoi - 15.9%, B. afzelii - 13.6%, Borrelia of unidentified species - 34.0%. The analysis recorded the differences in the infection ticks with B. afzelii, B. garinii and B. miyamotoi between different parts of the Baikal region.
Conclusions. The obtained data complement and expand the understanding of the species diversity of natural focal infections carried by ticks in the Baikal region and can be used in further scientific research and in organizing preventive and therapeutic measures in case of infection with the pathogens considered in the study.

Relevance. Brucellosis is a particularly dangerous zoonotic infectious disease, characterized by multiple lesions of organs with a high potential for transition to a chronic forms. In recent years a situation on brucellosis remains unstable epidemiologic in the Russian Federation.
Aim of study. The conduction of screening research in people living in brucellosis-unfavorable territories the cellular and humoral immunity indicators using antigen-specific in vitro tests.
Materials and Methods. The immunologic monitoring of volunteers from brucellosis-unfavorable territories of the Republics of Tyva (Khandagaiti village, Ovurskiy district, n=317) and Altai (Kosh-Agach village, Kosh-Agachskiy district, n=150), and employees from the institute (n=30). The research included determination of the presence of specific antibodies of class G to the brucellosis pathogen, concentrations of cytokines (IFN-γ, IL-2, etc.) and major classes of immunoglobulins in blood serum, spontaneous and antigen-induced production of cytokines by blood cells using ELISA, and immunophenotyping of blood lymphocytes by flow cytometry.
Results and discussion. Among all examined volunteers from unfavorable territories, specific antibodies to the brucellosis pathogen were detected in 113 people (24.2%). The IL-2 stimulation index in the seronegative volunteer group was found to be 2.3 times higher compared to the seropositive group. Positive results of the level of antigen-induced production (LAP) of IFN-γ were observed in 48 (16.8%) volunteers, which indicates the presence of T-lymphocytes with antigen-specific receptors to the brucellosis pathogen. IFN-γ’s LAP was found to be 8.3 times higher in volunteers with specific antibodies to the brucellosis pathogen. Humans diagnosed with brucellosis and vaccinated volunteers showed an increase in the stimulation ratio of T-lymphocyte activation markers (CD25 and HLA-DR) >51%.
Conclusion. Thus, the effectiveness of antigen-specific in vitro tests for assessing the formation of postvaccinal immunity and diagnosis of brucellosis infection was demonstrated. The introduction of annual immunologic monitoring of specific immunity against brucellosis in humans living in brucellosis-unfavorable territories of Siberia makes it possible to increase the effectiveness of the complex of measures to ensure epidemiological surveillance of brucellosis.

Relevance. The colon microbiota represents the richest human biotope in its biodiversity. The region of residence, particularly the Arctic zone, takes part in its formation. Currently, there are few studies examining the nature of the intestinal microbiota in individuals exposed to severe climatic conditions in northern regions.
Aim. To study the biodiversity of the colon microbiota in permanent and temporary residents of one of the Arctic regions (the city of Arkhangelsk).
Materials and methods. A cross-sectional study was conducted on 90 participants. A PCR study tested feces from 45 permanent and 45 temporary residents, with the reasearch of 33 indicators of microbial composition. The sample included young people from 18 to 45 years old, BMI within normal limits, without acute and chronic inflammatory diseases. Data presented in the form of quantitative data (lg CFU/g) and categorical (not detected, normal, less and more than normal). Statistical analysis included the use of Pearson and Mann-Whitney chi-square tests.
Results. Study showed common features among all residents of this region – a deficiency of obligate representatives of microflora: lactobacilli, enterococci, a reduced number of bifidobacteria, and functional Escherichia coli. Also, temporary residents had a higher number of B. thethaiotaomicron (p=0.005), Ruminococcus spp. (p = 0.01), F. nucleatum (p = 0.039), F.prausnitzii (p = 0.029), A.rectalis (p=0.042), Bacteroides spp. (p = 0.048), below A.municiphila (p = 0.057), Enterococcus spp. were more often detected (p = 0.008). Moreover, the results are comparable with data from residents of Irkutsk, St. Petersburg and Canadian Inuit, which indicates a tendency towards a decrease in obligate representatives of the microbiota among residents of the northern regions and an increase in opportunistic flora.
Conclusions. The results of the study demonstrate differences in the microbial composition of the colon in permanent and temporary residents of the city of Arkhangelsk, which belongs to the Arctic zone of the Russian Federation. Additional study of the diet of the subjects will allow us to analyze the hypothesis about the geographical features of this region and the impact of factors on the number of obligate representatives of microflora: lactobacilli, bifidobacteria, E. coli, enterococci.

Relevance. Currently, much attention is paid worldwide to diseases transmitted by vectors (bites of ticks, mosquitoes and horseflies). In our country, at least nine pathogens of zoonotic infections transmitted by this route are registered: tularemia, borreliosis, tickborne encephalitis, anaplasmosis, rickettsiosis, Q fever, babesiosis, bartonellosis and ehrlichiosis. In Russia, outbreaks of tularemia associated with the transmission of infection through bites of blood-sucking arthropods have increased, and waterborne and trench epidemic outbreaks have also been registered. Waterborne outbreaks are associated with the use of water contaminated with corpses or excrements from sick rodents. Trench outbreaks are associated with the mass settlement of military structures by rodents, in whose populations epizootics occur.
Goal Target. Determination of the epidemiological type of outbreak morbidity and the possibility of its elimination. Materials and methods. The materials were statistical data of Rospotrebnadzor on the incidence of tularemia, the volume of vaccination against this infection. Retrospective data on morbidity and epizootological studies from the archives of the Gamaleya National Research Center for Epidemiology and Microbiology of the Ministry of Health of the Russian Federation for 1997–2023, 375 cards of epidemiological investigations of tularemia cases were used. Reports of epizootological surveys of focal areas of the regions of the Russian Federation were analyzed.
Results and discussion. In the territory of the Federal Districts of Russia from 1997 to 2023 inclusive, 61 epidemic outbreaks of tularemia from 10 to 955 cases were registered, including 52 transmissible in the Central Federal District (13), Northwestern Federal District (18), Ural Federal District (5), Siberian Federal District (9), Volga Federal District (6) and Far Eastern Federal District (1). The total number of cases during the outbreaks was 3261 patients with tularemia, of which: 2754 cases of diseases from bites of blood-sucking arthropods (transmissive type of disease), 254 people fell ill after drinking raw water (water type of disease), 253 people fell ill while in trenches (trenches), where there was a large accumulation of rodents (trench type of disease). Bubonic and ulcerative-bubonic clinical forms of tularemia are typical for transmission through horseflies and mosquitoes, and when an insect gets into the eye, the ocular-bubonic form. Waterborne outbreaks of tularemia occur when drinking or washing with water. The main clinical forms of this type of disease are angina-bubonic, abdominal and ocular-bubonic, sometimes mixed - abdominal + angina. In the trench type of infection, pulmonary with bronchitis and pneumonic variants (thoracic), angina-bubonic (anginal-glandular) and abdominal (gastrointestinal) clinical forms of tularemia prevailed. The cause of the outbreak was a combination of natural factors, lack of immunity in the population and insufficient awareness of the etiological diagnosis of the infection. With the cessation of human morbidity, the natural focus of tularemia does not cease to exist, and with a decrease in the number of vaccinated, and therefore susceptible to the pathogen, a threat of a new outbreak arises.
Conclusions. In order to ensure epidemiological well-being in terms of tularemia, it is necessary to maintain the level of vaccination and revaccination within 2.5–3 million per year of contingents subject to vaccination, taking into account the degree of epizootic activity of natural foci. Epidemic outbreaks of tularemia may occur against the background of a significant decrease in the volume of vaccination of the population living in areas enzootic for this infection. Tularemia is characterized by polymorphism of clinical manifestations, therefore, a carefully collected epidemiological history is of great importance for the diagnosis of this infection. It is necessary to conduct explanatory work on preventive measures among the population living in areas endemic for tularemia in connection with multiple refusals of vaccination against tularemia. It is necessary to carry out measures to improve the sanitary and epidemiological literacy of doctors regarding tularemia infection.

Background. The prevalence of multidrug-resistant tuberculosis poses a serious public health problem, hampering the success of tuberculosis control programs around the world.
Aim: Evaluation of epidemiological manifestations of tuberculosis and molecular genetic characteristics of Mycobacterium tuberculosis strains with multiple drug resistance circulating in the Omsk region.
Materials and methods. In accordance with the generally accepted algorithm of descriptive and evaluative epidemiological research, the incidence and prevalence of tuberculosis in the Omsk region for the period 2009–2023 were studied. The material for the study was the data from official statistical observation forms. A total of 595 strains of M. tuberculosis isolated from newly diagnosed patients with TB in the Omsk region in the period from 2019–2022 were studied. Cultivation of M. tuberculosis, determination of drug susceptibility, and DNA isolation were carried out using standard methods. Belonging of the strains to the Beijing genotype, its sublineages and clusters was determined using PCR based on the analysis of specific markers. Non-Beijing strains are spoligotyped.
Results. In the Omsk region, the dynamics of tuberculosis incidence and prevalence of tuberculosis were characterized by a pronounced downward trend, reaching 43,7 and 66,8 per 100 thousand, respectively, in 2023. The prevalence of multidrugresistant tuberculosis remains significant (22,6 cases per 100 thousand population), and the proportion of MDR tuberculosis cases among newly diagnosed patients increased from 13,1% in 2009 to 28,4% in 2023. In the sample set of strains, 40,5% had MDR, 13,2% had pre-XDR. Genotyping of MDR (including pre-XDR) M. tuberculosis strains revealed the prevalence of the Beijing genotype (86.3%), in particular the subtypes: B0/W148 (38,2%), Central-Asian/Russian (34,4%), as well as clusters 1071-32 (10,0%) and 14717-15 (2,1%) of the ancient sublineage. The most numerous among the non-Beijing was the SIT262 spoligocluster (5,0%) of the Ural genotype.
Conclusion. Against the background of a significant decrease in the prevalence and incidence of tuberculosis, the proportion of newly identified MDR-TB strains has increased. At the same time, molecular genetic monitoring of M. tuberculosis has revealed the key role of B0/W148 and Central-Asian/Russian Beijing subtype strains in the spread of MDR-TB. The results obtained demonstrate the spread of multidrug-resistant strains, providing information for making clinical and management decisions in the implementation of regional tuberculosis control programs.

Relevance. Vaccination is one of the main tools of public health that helps prevent the spread of infectious diseases and maintain the health of the nation. Healthcare workers play a crucial role in vaccination matters. The confidence of healthcare workers in the necessity, effectiveness, and safety of vaccination largely determines its acceptance by the population and ultimately the success of the vaccination campaign as a whole.
Aim. To study the level of vaccination adherence among healthcare workers in the Russian Federation.
Materials and methods. A cross-sectional epidemiological study was conducted, consisting of three stages implemented according to a unified design. The first stage of information gathering (using anonymous electronic questionnaire) was carried in 2019, followed by the second stage in 2021, and the third one in 2023. Participants for the study were recruited using the database of National Association of Specialists for the Control of Healthcare-Associated Infections (NASCI), further sampling was formed using the snowball method. In total, over three periods, 146.244 (31.330 in 2019, 85.218 in 2021 and 29.696 in 2023) questionnaires from medical professionals of various specialties (doctors and mid-level medical staff) were analyzed. Responses were received from representatives of 79 out of 85 regions of the Russian Federation in 2019 and 2021, and from 66 out of 89 regions in 2023. For analysis and presentation of the obtained data, standard methods of descriptive statistics were used (test for normality, calculation of averages and 95% confidence intervals for quantitative variables, calculation of proportions, 95% confidence interval for qualitative variables). Statistical associations between two non-normally distributed quantitative variables were evaluated using Spearman's correlation coefficient, the statistical significance of differences in groups of qualitative variables was evaluated using the Pearson’s chi-square test at p<0.05 IBM SPSS Statistics v. 22.
Results. 73.8% ± 0.5% of medical workers in the Russian Federation have a positive attitude towards vaccination, 19.3% ± 0.3% are neutral, 6.9% ± 0.3% are negative in 2023. During the COVID-19 pandemic (2021), there was a significant decrease in vaccination adherence – during this period, the share of medical workers who have a negative attitude towards vaccination increased from 1.8% ± 0.2% to 18.0% ± 0.3%. The adherence of mid-level medical staff (nurses) is significantly lower than that of doctors 61.9% ± 0.3% and 79.9% ± 0.3%, respectively). The highest level of adherence is observed among pediatricians 93.4% ± 0.4%, epidemiologists 92.5% ± 1.3%, allergists-immunologists 86.1% ± 2.9%, infectious disease specialists 84.6% ± 2.2%, therapists 83.3% ± 0.5%, pulmonologists 81.8% ± 4.5%. The level of commitment among health-care workers directly involved in vaccination are 22.8% ± 12.2% higher than those who do not participate (χ2 = 3918.3, p < 0.001). The vast majority of medical workers (94.4% ± 0.2%) recommend vaccination to their friends and relatives, most this applies to vaccinations against measles, hepatitis B, diphtheria, tetanus, and to a lesser extent – against infections against which vaccination is not included in the National Immunization Schedule. The majority of medical workers (72.0% ± 0.5%) are interested in receiving additional information on the vaccination.
Conclusions. Awareness-raising, along with providing accessible, effective and safe vaccines, plays a key role in improving healthcare workers’ adherence to vaccination, reducing both infectious and non-infectious diseases among the population.

The study describes the long-term dynamics of wild and vaccine-derived polioviruses (VDPV) circulation from 2014-2023, and to describe polio surveillance methods. Cases of disease caused by wild poliovirus in 2023 were reported in Afghanistan and Pakistan, which, in case of declining vaccination coverage, may lead to the introduction of wild virus into currently polio-free country. This study presents information about various sources VDPV. VDPV were found in environmental objects worldwide and were found to be a major cause of acute flaccid paralysis. The information about poliovirus circulation in this article confirms the need to maintain high immunization coverage with trivalent IPV, to develop m-OPV2 production for rapid outbreak response, and to improve epidemiological surveillance methods.