Search

The aim of the work was to analyze the epizootic and epidemiological situation on leptospirosis in the territory of the Russian Federation in 2023 and to forecast its development for 2024. In the period between 2000 and 2023, the long-term dynamics of morbidity in Russia tended to decrease. Leptospirosis incidence was mainly sporadic. In 2023, cases of this infection in humans were reported in all federal districts, with the exception of the North Caucasian one. The highest incidence rates were recorded in the Southern and Central Federal Districts. The results of testing material from small mammals using bacteriological, immunological and molecular-biological methods confirmed the circulation of pathogenic Leptospira in 50 constituent entities of the Russian Federation in all federal districts. Specific prevention measures were carried out: 20,114 people were vaccinated in 27 entities. The probability of human infection is higher in the territories of the Southern, Central, Northwestern, Volga and Ural Federal Districts. Imported cases of infection from regions with subequatorial and equatorial climates, which are actively visited by tourists, are not excluded.

Cholera vibrios, isolated from surface water bodies during monitoring activities, can differ from typical ones in terms of agglutinability with diagnostic cholera sera, which makes it difficult to assign them to a specific serogroup. Therefore, the determination of the causes for these deviations through the study of the structure of genetic determinants responsible for the synthesis of O‑antigen (wb* clusters) is considered a relevant task. The aim of this work was to identify wb* clusters in the genomes of R-variant Vibrio cholerae, study their structure, and conduct phylogenetic analysis of the strains. Materials and methods. Full genome sequencing was performed using Illumina MiSeq and MinION platforms. The assembly was conducted de novo using the SPAdes assembler software (v.3.11.1). Manipulation of cluster sequences and data visualization were carried out using the BLAST program from the ncbi-blast-suite package version 2.13.0, Python scripts and packages such as pyGenomeViz and Biopython. The phylogenetic tree was constructed using the roary program (v.3.13.0). Full genome alignment was carried out using the nucmer and promer programs from the MUMmer 4 package version 4.0. Results and discussion. R-variant V. cholerae contains different types of wb* clusters in the genome, with most commonly occurring O23 and O59. A comparison has been made between translated amino acid sequences of wb* regions in R-variant strains and amino acid sequences of reference strains present in the NCBI database. Some of the analyzed clusters completely match with reference strains, while others show high variability. Phylogenetically, the strains primarily group together according to the wb* cluster type, regardless of the S/R phenotype. Classifying R-variant V. cholerae strains based on agglutinability is challenging. Molecular research methods, polymerase chain reaction, in particular, are necessary to determine the pathogenic potential of such strains.

The aim of the study was to compare outer membrane vesicles (OMVs) and their composition in virulent and avirulent (LPS-defective) strains of Fracisella tularensis of various subspecies. Materials and methods. The vesiculation process in F. tularensis bacteria was studied using transmission electron microscopy. OMVs preparations were obtained and characterized by their composition using immunological methods: antibody neutralization test, immunochromatographic analysis, dot and immunoblotting. Results and discussion. It has been found that all natural virulent strains with the S type lipopolysaccharide (LPS) are able to produce two forms of vesicles – spherical and tubular (“tubes”), specific for F. tularensis. OMVs formation has not been registered in avirulent LPS-defective strains. It is revealed that vesicles of strains of various subspecies show their own individual morphological features. The tubes of F. tularensis subsp. mediasiatica are larger in size as compared to those of the subsp. holarctica strain. This is probably the reason why vesicle preparations from F. tularensis subsp. mediasiatica obtained using filters with a diameter of pores being 0.22 μm contained a significantly reduced number of tubular forms. A method of disinfection of bacterial suspensions using gentamycine, which does not affect the morphology and antigenic activity of vesicles, is proposed. A comparative study of several series of concentrated OMVs preparations obtained from different strains has revealed that all samples had antigenic activity in the precipitation Ouchterlony test, antibody neutralization test, immunochromatografic assay, dot-blot and immunoblotting. Immunodominant antigen – LPS and several major antigenic proteins have been detected in the preparations. Differences in the composition of vesicle proteins in the strains of various F. tularensis subspecies have been identified.

The aim of the work was to perform a brief overview of the data on the development, the main tasks of the Federal State Institution of Health “Rostov-on-Don Research Anti-Plague Institute of the Federal Service for Surveillance on Consumers’ Rights Protection and Human Wellbeing (Rospotrebnadzor) and its contribution to ensuring the sanitary and epidemiological welfare of the population of the Russian Federation. The review is based on the analysis of the reports on research work, archive materials and literature sources. Currently, priority and promising areas of research at the Institute are: epidemiological monitoring of cholera pathogens and natural-focal infections with an assessment of epidemiological risks and threats based on advanced methods of detection and identification of agents; development of measures aimed at preventing the spread of infections; epizootiological survey of natural foci of particularly dangerous infections; development of predictive modeling risk assessment systems, new techniques and approaches to improve laboratory diagnostics and epidemiological surveillance; development of sequencing; modernization of monitoring, including using molecular biological methods, and control of infectious diseases using geo-information technologies; transition to genomic epidemiological surveillance; improvement of unified online databases, creation of technologically independent, unified software platforms for bioinformatic analysis of the results of genome-wide sequencing; research of genetic markers of antibiotic resistance, as well as immunopathogenetic aspects of the course of particularly dangerous and other infections; ensuring interaction with all interested services and agencies in organizing and conducting events within the framework of sanitary protection of the territory. Relying on the vast experience of predecessors and stateof-the-art knowledge, the Rostov-on-Don Research Anti-Plague Institute of the Rospotrebnadzor actively takes part in solving topical issues to scientifically and practically support the provision of sanitary-epidemiological well-being and biological safety of the population of the Russian Federation.

The aim of the work was to determine the pheno- and genotypic features of the aquatic CTX+ strain of Vibrio cholerae isolated in 2023 and a comparative bioinformatic analysis of whole-genome sequencing data.Materials and methods. Whole-genome sequencing was performed on MiSeq (Illumina) and MinIon Oxford Nanopore Technologies (ONT) platforms; hybrid assembly of the whole genome was carried out using the Trycycler algorithm; assembly errors were eliminated by means of the Medaka algorithm and the Pilon program. Dendrogram construction and bioinformatics analysis were carried out with the help of the scipy and Graphviz packages, BioEdit, BLASTN, BLASTP, CARD, ICE Genotyper, and Vector NTI programs. The ability to produce cholera toxin was tested using the GM1ELISA.Results and discussion. The isolated strain was identified as V. cholerae O1 Ogawa, sensitive to most antibiotics. Based on the totality of genetic properties, it was classified as the first genovariant, distinct from the typical El Tor strains only by the presence of ctxB1 gene of classical type instead of ctxB3 of the El Tor type. It has been established that it contains a tandemly duplicated CTX prophage on the small chromosome and a tandem of two copies of RS1 prophage on the large chromosome. Thereat, the rstR gene of the CTX prophage belonged to the classical type, and the RS1 prophage – to the El Tor type. The remaining criteria of epidemic hazard – tcpAelt, rtxA1 and intact VSP-II did not differ from the prototypes. The genome of the strain carries the ICE element VchBan11, which contains the trimethoprim resistance gene dfrA1, and phenotypically the strain is resistant to this antibiotic. Under in vitro conditions, the strain did not produce cholera toxin, as shown by ELISA results. This may be due to the presence of a deletion within the toxR regulatory gene. Strains similar to the 2023 isolate are mainly attributed to the second wave of the seventh pandemic. Currently, they are almost replaced by new genovariants, but occasionally can emerge and even cause diseases. Therefore, their importation into Russian territory potentially pose a threat to public health.

Objective: to characterize the dynamics and intensity of the incidence of Q fever for the period from 2015 to 2022, to determine the risk areas for human infection in the Southern and North Caucasian Federal districts and in the new subjects of the Russian Federation.Materials and methods: for epidemiological analysis, materials from analytical reviews "The epidemiological situation of natural focal infectious diseases in the Southern and North Caucasus Federal Districts" and state reports "On the state of sanitary and epidemiological welfare of the population" for 2015-2022, reporting data from the Rospotrebnadzor Department for the Rostov region, «Center for Hygiene and Epidemiology in Russia Rostov region» and the Departments of Rospotrebnadzor for the DPR and LPR. From 2022–2023 PCR study was conducted for the presence of Coxiella burnetii DNA in samples of ixodic mites and small mammals in the Rostov region and in 2023 – in the DPR, LPR, Zaporizhia and Kherson regions.Results: the analysis of the territorial distribution of cases of Q fever in the Astrakhan region and Stavropol Territory revealed a cluster of the most disadvantaged areas. An analysis of the conditions of infection of patients with Ku fever in the Rostov region has established that the most likely transmission factors are environmental objects in private farms. The circulation of C. burnetii in natural biotopes of the Rostov region, DNR and LNR regions.Conclusions: the epidemic process of Ku fever is mainly local, limited in the context of municipal districts of Astrakhan and Rostov regions, Stavropol Territory. The sporadic incidence of Ku fever does not reflect its actual level. There is no convincing evidence indicating the leading role of farm animals as a primary link in the formation of the epizootic process of Q fever in anthropurgical foci.

Objective: to form a brief overview of data on the interactions of the Rostov-on-Don Anti-plague Research Institute with the other state institutions ensuring the sanitary and epidemiological population wellbeing.Materials and methods: analysis of archive materials and literature sources from databases and electronic libraries such as E-library, CyberLeninka, etc.Results: We have described the main directions of the interactions of the Rostov-on-Don Anti-plague Research Institute with the institutions of Rospotrebnadzor (Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing) and the Ministry of Health of the Russian Federation, that have been directed on realization of collaborative studies, planning of cooperative publications, organizing and conducting advisory, methodological and practical assistance. Special attention has been paid to the activities that bring together specialists from both research and educational institutions and practical health-care in the Rostov region.Conclusion: Coordinated actions of specialists from the Rostov-on-Don Anti Plague Research Institute with the bodies and organizations of Rospotrebnadzor, Ministry of Health of the Russian Federation on improvement of epidemiological surveillance, diagnostics and prevention of infectious diseases allow us to carry out effective surveillance of especially dangerous infections and to promote improvement of professional level of profile specialists.

Background. The study of the phylogeography of the tularemia microbe is not only practical, but also of scientific interest, as it allows us to evaluate the evolutionary processes of Francisella tularensis in modern conditions.Aim. Phylogenetic analysis of strains of the causative agent of tularemia in the Rostov region and identification of erythromycin-sensitive genovariants.Results. A representative collection of 122 cultures, isolated from various sources from 1945 to 2022, was studied. As it was established, all the studied strains of the causative agent of tularemia had typical cultural, morphological, and biological characteristics. The results of the study of bacteria antibiograms showed that all strains were resistant to β-lactams, polymyxin, clindamycin, and sensitive to aminoglycosides, rifampicin, and fluoroquinolones. In relation to erythromycin, only 2 erythromycin-sensitive strains were found. Phylogenetic analysis of 34 European and Russian strains of F. tularensis made it possible to determine whether these strains belong to subgroup B.7 of the main genetic group B.6.Conclusion. For the first time, in the Tselinsky district of the Rostov region, the presence of «atypical» genovariants of the tularemia microbe belonging to subgroup B.7 of the main group B.6 of the subspecies holarctica was registered, according to the modern scheme of genetic typing of F. tularensis subsp. holarctica.

The paper presents an analysis and assessment of risks of complication of epidemiological situation regarding cholera in the Russian Federation and a forecast for 2024. It briefly characterizes the dynamics of the epidemic process around the world during the last decade (2013–2022). The forecast of cholera importation into the Russian Federation, due to activity of the epidemic process in endemic countries, has been confirmed. In 2023, two cases of cholera importation from India were reported. It was established that the toxigenic strains isolated from patients belonged to the currently dominant in the world “post-Haitian” group, including in India and Bangladesh, with the genotype ctxB7 tcpACIRS rtxA4a VSP-IIΔ0495-0512. Furthermore, non-toxigenic Vibrio cholerae O1 strains were isolated from samples of biological material from persons arriving from India, containing preCTX prophage and distinct from the strain (ctxAB– tcpAEТ–) isolated from a patient with acute intestinal infection (Zaporozhye Region, Melitopol). Nontoxigenic NAG vibrios were isolated from 13 patients with acute intestinal infections, which is 1.9 times more than in 2022. Regardless of importations, a strain of V. cholerae O1 (ctxB1+tcpAEТ) of the “pre-Haitian” group was isolated from a water sample of a surface reservoir. 52 non-toxigenic V. сholerae O1 strains were found on the territory of 11 constituent entities of the Russian Federation, which is 18.9 % more than in 2022. In 2024, epidemiological risks of cholera importation from endemic countries to any administrative territory of the Russian Federation remain. The risks of epidemic manifestations of cholera are especially high in the territories of the constituent entities of the Russian Federation which are under ongoing emergency, due to migration processes, and the impact of other risk-forming factors that contribute to an increase in the degree of contact of the population with water bodies contaminated with cholera vibrios. If epidemic foci of cholera are to emerge in a neighboring country, there will be a high probability of spread of this infection in the stated constituent entities of the Russian Federation and in other territories of southern Russia. In the absence of epidemic manifestations of cholera, the possibility of occasional detection of toxigenic O1 serogroup strains in water samples due to unidentified introductions from cholera-affected areas cannot be ruled out.

An epizootological inspection of the liberated territories of the Donetsk and Lugansk People's Republics, Zaporozhye and Kherson regions was carried out. It was established that the faunal complex of small mammals, hare-like and ectoparasites, as well as their number, make it possible to ensure the circulation of natural focal infections identified by the results of laboratory studies: tularemia, Crimean hemorrhagic fever (CHF), West Nile fever (WNF), ixodic tick-borne borreliosis (ITB), rickettsiosis, human granulocytic anaplasmosis (HGA), leptospirosis, hemorrhagic fever with renal syndrome (HFRS), Q fever, intestinal yersiniosis, Batai, Inco, Sindbis, Tyaginya fevers. For the first time, the PCR method in field material from the Zaporozhye region (Berdyansk and Melitopol regions) detected the Crimean-Congo hemorrhagic fever virus, on the territory of the Donetsk and Lugansk People's Republics in the populations of small mammals (rodents and insectivores), the circulation of viruses Inco, Sindbis, Tyagin, Batai was established. In the territories of Kherson and Zaporozhye regions, the presence of combined and conjugated natural foci of ixodic tick-borne borreliosis, rickettsiosis and human granulocytic anaplasmosis is determined. According to the results of molecular genetic analysis, it was shown that the causative agents of natural focal infections (Crimean hemorrhagic fever, West Nile fever, ixodic tick-borne borreliosis, rickettsiosis) identified in 2023 are genetically close to strains circulating in the regions of the south European part of Russia.

Objective: to study the level of the immune layer of the population to pathogens of natural focal infectious diseases in order to establish the epidemic activity of natural foci of particularly dangerous infectious diseases in the Rostov region.Materials and methods: blood serums of healthy donors living in the administrative territories of the region were collected in the period from 2020 to 2022. Specific antibodies in blood sera were determined by the ELISA method. Serum specific IgG class immunoglobulins were used as a serological marker of the transmitted infection.Results: IgG to the Crimean hemorrhagic fever virus was not detected in 2020. In 2021, the share of seropositive results was 0.7%, in 2022 — 2.0%. The proportion of IgG to West Nile virus in 2020 was 8.7%, in 2021 — 9.9%, in 2022 — 12.4%. Serological testing revealed an immune layer to ixodic tick–borne borreliosis in 2020–2022: 3.1%, 2.6% and 2.0%, respectively. Antibodies to hantaviruses, pathogens of hemorrhagic fever with renal syndrome in the blood of residents of the region in 2020 were found in 7.0% of samples, in 2021 — 4.5%, in 2022 — 7.1%. The share of positive samples in the study for Ku fever in 2022 was 2.3%. Conclusion: Seropositive samples were detected for all studied natural focal infections. The greatest variety of natural focal infections confirmed by serological monitoring data was detected in cities (Rostov-on-Don, Taganrog, Zernograd, Kamensk-Shakhtinsky) and districts of RO (Salsky, Neklinovsky, Remontnensky).Conclusion. The results of the serological monitoring made it possible to identify the circulation of pathogens of KGL, LZN, ICB, Ku fever, hantaviruses in the territory of two districts of the region. The detection of specific antibodies in the blood sera of healthy donors indicates the epidemic activity of natural foci. Also, a comprehensive study of healthy donors expanded the understanding of the area of the most relevant natural focal infections such as (KGL, LZN, ICB), and less frequently registered at present (HFRS and Ku fever).

Background. In a novel coronavirus pandemic, the most common complications of viral pneumonia are secondary infections of bacterial and fungal etiology. At the same time, the spread of multidrug-resistant bacteria remains a global threat to public health. One of such microorganisms of the Enterobacteriaceae family is Klebsiella pneumoniae, which belongs to dangerous resistant pathogens of the ESKAPE group.The aim of the study was the comparative analysis of the biological properties of classical and hypermucoid strains of K.pneumoniae isolated from patients with community-acquired pneumonia (CAP): characterization of their sensitivity to antibacterial drugs, Klebsiella bacteriophage, and a disinfectant (polyhexamethylene guanidine hydrochloride), as well as assessment of the strains’ virulence in the model of experimental infection in white mice.Material and methods. 56 strains of Klebsiella isolated in diagnostic quantities from patients’ sputum samples were studied. Species identification of cultures was carried out using bacteriological and mass spectrometric methods. The sensitivity of bacteria to antibiotics, bacteriophage, and the disinfectant was determined in accordance with regulatory documents.Results. In the course of the study, 243 gram-negative cultures were isolated, of which 30% were bacteria of the genus Klebsiella spp. An analysis of their species composition showed that K.pneumoniae occupied a dominant place in the structure. Based on colony morphology, Burri-Gins smear staining, and a positive string test, 14 strains with a hypermucoid phenotype were identified. These strains differed from the classic K.pneumoniae strain by the presence of a thicker capsule in smears, virulence in white mice (DCL≤103 mc), and increased resistance to commercial Klebsiella bacteriophage. At the same time, they were characterized by a wider spectrum of sensitivity to antibiotics. There were no significant differences in sensitivity to the disinfectant in strains of both morphotypes.Conclusion. The results obtained demonstrated the important role of K.pneumoniae in the etiological structure of CAP pathogens.

The aim of the study was to conduct a comparative analysis of the spectrum and antibiotic resistance of secondary pneumonia pathogens isolated in the territories of the Rostov, Tyumen Regions and Khabarovsk Territory against the background of a new coronavirus infection pandemic.Materials and methods. We investigated sputum samples from coronavirus-positive and coronavirus-negative patients with community-acquired pneumonia from medical organizations using bacteriological method, PCR mass spectrometry.Results and discussion. The study of the etiological structure of secondary pneumonia agents isolated from patients in medical organizations of the Southern, Ural and Far Eastern Federal Districts has revealed that the dominant cultures in SARS‑CoV‑2 “+” and SARS‑CoV‑2 “–” patients were yeast and yeast-like fungi. It has been found that under diversity of isolated fungi, Candida albicans species prevailed. The bacterial microflora is represented by a variety of gram-positive and gram-negative bacteria, of which Staphylococcus aureus and Klebsiella pneumoniaе were most often present in sputum. It has also been established that even before hospitalization of patients, community-acquired pneumonia could be caused by microorganisms of the ESKAPE group (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniaе, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp.), which are usually considered as polyantibiotic-resistant pathogens of nosocomial infections. Moreover, in coronavirus-positive patients with secondary community-acquired pneumonia, those pathogens were isolated 2–3 times more frequently than in coronavirus-negative ones. Assessment of sensitivity/resistance of isolated strains to antibacterial drugs has revealed a general trend: the majority of the strains, regardless of the type, were characterized by a narrow spectrum of sensitivity, having 3 or more markers of antibiotic resistance. This confirms the necessity and expediency of microbiological support of the patient during the entire infectious process. The most adequate drugs of choice, providing activity against 60–70 % of strains of the Enterobacteriaceae family, are amikacin and cefoperazone/sulbactam.

The aim of the work was to identify genotypic features of clonal complexes formed by CTX–VPI+ strains of Vibrio cholerae isolated from water bodies of the Rostov Region in different years, based on bioinformatics analysis of their whole genome sequences (WGSs).Materials and methods. Whole genome sequencing was performed on the MiSeq (Illumina) platform; identification of genetic determinants in WGSs and bioinformatics analysis – by means of BioEdit, BLASTN, BLASTP, CARD, Vector NTI software packages.Results and discussion. The strains were almost identical in each group of 2002-, 2005-, 2007-, 2020-, 2021-, and 2022-isolates and were found at different points of water sampling over a longer or shorter periods of time (from 3 weeks to 2 months). Bioinformatics analysis of WGSs of representative strains divided them into 4 clusters, which can be considered as separate clonal complexes sharing a number of characteristic genetic markers: 1) 2002-isolates containing one SNP in regulatory rpoS gene; 2) 2007-strains carrying tandemly duplicated preCTX prophage; 3) strains isolated in 2020 in Rostov-on-Don and in 2005, during epidemiological complications in the Kamensk district of the Rostov Region, which had a “hybrid” pathogenicity island including the cluster of type 3 secretion system and the nan-nag region of the VPI-2 island, and 9 SNPs in rpoS gene; 4) 2021- and 2022-strains and a single 2018-isolate containing a 9 bp deletion in vchC collagenase gene. Despite the revealed differences, representatives of all clonal complexes possessed sufficient sets of intact determinants of pathogenicity/persistence factors to realize virulent properties and ability to survive in water bodies. Detection of clonal complexes of potentially pathogenic strains in surface water bodies indicates occasional emergence of favorable conditions for their long-term circulation, which emphasizes the importance of constant monitoring of V. cholerae in the territory of Russia.

The aim of the work was to study the structure of the alkyl sulfatase (asu) gene in Vibrio cholerae strains of various serogroups, as well as to compare nucleotide and amino acid sequences of alkyl sulfatases using various methods of bioinformatic analysis.Materials and methods. 483 strains of V. cholerae O1, O139 and nonO1/nonO139 serogroups were employed in the work. The search for the gene, its recurrence, and localization was carried out applying the Blast software. The nucleotide and corresponding amino acid sequences of the gene, as well as its structure, were studied using bioinformatic analysis. Sequencing was performed on the MiSeq (Illumina) platform. The enzymatic activity was detected using a medium, confirming the presence/absence of the gene by PCR in vitro and in silico.Results and discussion. Bioinformatic analysis of the nucleotide and corresponding amino acid sequences of the asu gene has been carried out and its structure investigated. Four functional domains have been identified. In the beta-lactamase domain, a conservative amino acid sequence -HAHADH- has been found in all strains of cholera vibrios, which is part of the Zn2+ binding motif. It has been established that the alkyl sulfatase of cholera vibrios belongs to the family of Zn2+-dependent β-lactamases. Blast analysis has revealed the similarity of nucleotide and amino acid sequences of alkyl sulfatases in representatives of V. cholerae O1 and O139 serogroups (ctxAB+tcpA+) and representatives of the genera Aeromonas and Pseudomonas, which is in the line with the data of 3D modeling of the amino acid sequence structures of the alkyl sulfatase enzyme in these microorganisms. The bioinformatic analysis of nucleotide and amino acid sequences of alkyl sulfatases in cholera vibrios has showed the conservativeness of these sequences in toxigenic strains and the presence of a number of single mutations in the asu gene in atoxigenic ones. The presence or absence of the asu gene has been established by PCR in vitro and in silico and confirmed by the results obtained using the Blast program. It is demonstrated that the presence/absence of the asu gene correlates with the ability/inability of O139 strains to hydrolyze SDS on the medium. These results can be used in studying mechanisms of cholera vibrios adaptation, persistence and pathogenicity.

Determination of Vibrio cholerae affiliation to one or another serogroup may meet some difficulties in cases of atypical agglutination with diagnostic cholera sera. The study of genetic determinants that allows for identifying a serogroup is a relevant task in monitoring of surface water body contamination with cholera vibrios.The aim of the work was to compare the structural organization (quantitative and qualitative gene composition) of LPS clusters in V. cholerae rough variants.Materials and methods. We used Illumina MiSeq for the whole genome sequencing; SPAdes software (version 3.11.1) for de novo assembly; and blastn (v. 2.5.0) for gene searching. GeneMarkS software was deployed for annotation of the genes incorporated in the clusters; nucmer – for searching homologous sites. Visualization of O-LPS clusters was carried out by means of SnapGene Viewer.Results and discussion. Strains of V. cholerae rough variants had diverse gene clusters responsible for O-antigen biosynthesis. We have identified three types of O-LPS clusters with different size and number of genes. Unique DNA sites, common to the whole group of V. cholerae rough variants, have not been detected. Two genes present in all rough strains have been defined, but they are not unique for this group of strains and can be found in representatives of other serogroups. For two types of clusters, a region containing the IS‑element, common with V. cholerae O1, has been revealed.

Six cultures of tularemia microbe from fallen and captured live animals were isolated during epizootiological monitoring in the steppe focus in the south-east of the Rostov Region in 2020 against the background of extensive epizootics in the populations of the common vole Microtus arvalis obscurus and the public vole Microtus socialis.The aim of the work was to develop an SNP-typing scheme and to conduct a comparative study of the phylogenetic relations between Francisella tularensis strains isolated in the Rostov Region (2020) and strains from other regions.Materials and methods. Genome-wide sequencing was performed on the MiSeq Illumina platform. The author’s software GeneExpert, PrimerM and VirtualPCR, written in the Java programming language, were used for the analysis.Results and discussion. The strains of tularemia agent, isolated on the territory of the Rostov Region in 2020, can be allocated to two different clusters. It is established that two strains of tularemia pathogen (F0884 and F0889) isolated in Turkey are genetically close to some isolates circulating in the Rostov Region. A unique INDEL marker characteristic of this group of strains has been identified. The comparison of our proposed typing scheme with the scheme of “canonical” SNPs has showed a fairly good consistency and convergence of results within large clusters, meanwhile using a set of 6626 SNPs allows for differentiating the strains within one canSNP type. It is revealed that the vaccine strain has a common canSNP type with clinical and natural strains. A set of SNP markers has been selected for comparative analysis. A new INDEL marker that enables intraspecific typing of F. tularensis has been discovered and the possibility of its application in vitro and in silico has been comfirmed.

Objective: to form a brief overview of data on the main historical stages in the development of medical societies in Russia and the contribution of the Rostov branch of the All-Russian Scientific and Practical Society of Epidemiologists, Microbiologists and Parasitologists to ensuring the sanitary and epidemiological well-being of the population. Materials and methods: analysis of archival materials and literary sources from the databases of electronic libraries e-library, CyberLeninka and others. Results: the contribution of medical societies to the development of domestic medicine and the sanitary and epidemiological service of our country is indicated. Particular attention is paid to the activities of the Rostov regional branch of the All-Russian Scientific and Practical Society of Epidemiologists, Microbiologists and Parasitologists, which brought together specialists from both research and educational institutions, and practical health care of the Don region. Conclusion: The results of practical undertakings and scientific research of medical societies throughout their existence contributed to the development of preventive medicine and were focused on protecting the health of the country's population. The activities of the Rostov Regional Branch of the All-Russian Scientific and Practical Society of Epidemiologists, Microbiologists and Parasitologists are aimed not only at developing domestic medical science and promoting achievements among the medical community and the population, but also at improving the professional level of specialized specialists, developing and implementing effective scientific, practical, educational technologies .

Objective: evaluation of the epizootic and epidemiological situation for HFRS in the Rostov region. Materials and methods: from 2020 to 2022, an enzyme-linked immunosorbent assay was used to study the presence of hantavirus antigens in samples of small mammals and class G immunoglobulins in the blood sera of healthy donors. Results: epizootological monitoring conducted in 35 administrative districts of the region and in the vicinity of Rostov-on-Don (2157 animals, 15 species) revealed the circulation of hantaviruses in populations of small mammals. Infection with hantaviruses of six species of mammals was registered: house mouse, common vole, yellow-bellied mouse, European forest mouse, East European vole, small forest mouse. 1062 blood samples from residents of various regions of the region were tested. Class G antibodies to hantaviruses were detected in 7.0%, 4.5%, 7.1% in different years. Conclusions: the coincidence in the territories of Azovsky, Kamensky, Neklinovsky, Salsky, Morozovsky districts of positive findings of the hantavirus antigen in samples of small mammals and seropositive samples of donors suggests the presence of a natural focus of HFRS, the establishment of boundaries and activity of which needs further research.

Hemorrhagic fever with renal syndrome (HFRS) is registered in various geographical regions of the Russian Federation and occupies one of the leading positions among natural-focal human diseases in Russia. The aim of the study was to assess the epidemiological situation on HFRS in the Rostov Region. Materials and methods. Laboratory diagnostics of field material (samples from wild rodents) for the presence of antigens of HFRS pathogens and screening of blood sera from donors, residents of the region, for the presence of class G antibodies to viruses that cause HFRS were carried out by enzyme immunoassay during 2020 and 2021. Results and discussion. Hantavirus antigens were identified in five administrative districts of the Region in 2020, infection with HFRS virus in small mouse-like rodents was 7.1 %. In 2021, spontaneous infection of carriers was detected in 2.8 % of the samples, found in four districts of the Region. The presence of the virus markers was recorded in populations of five species of mouse-like rodents: house mouse, wood mouse, common vole, small wood mouse, yellow-bellied mouse. Among healthy population, class G antibodies were registered in 6.8 % in the surveyed territories in 2020, and 4.5 % in 2021. Detection of virus markers in carriers and the presence of a natural immune layer of the population as regards HFRS agents suggest the existence of a natural HFRS focus in the Rostov Region.

The tactics of activities of the specialized anti-epidemic team (SAET) of the Rospotrebnadzor on the territory of the Republic of Crimea has been determined by the conditions of emergency situation of sanitary-epidemiological and natural character. The aim of the work was to analyze the features and effectiveness of the functional response of the Rospotrebnadzor SAET to the dynamics of epidemiological risks caused by emergency of combined nature in the Republic of Crimea in 2020–2021. Materials and methods. We used report materials of the Rospotrebnadzor SAET; information materials of the Interregional Rospotrebnadzor Administration in the Republic of Crimea and the Federal city of Sevastopol; “Coronavirus Monitor” service data. Results and discussion. Tactical decisions on the work of the SAET on the territory of the Republic of Crimea had the stage-by-stage nature. In the event of a complication of the epidemiological situation on the new coronavirus infection, a mobile group of the SAET was involved. Together with specialists from the Plague Control Station of the Republic of Crimea, it conducted 211 148 studies of clinical material to detect SARS-CoV-2 RNA using PCR during the period of 2020–2021. In response to the emergence of additional risks caused by the consequences of a dangerous meteorological phenomenon, the group of SAET specialists was reinforced and mobile complex (MС) of the SAET was deployed. During the entire course of work, a prolonged target rotation of personnel was implemented in order to provide for adequate laboratory support for monitoring upon epidemiological indications in accordance with the nature of emerging risks. That tactics of operation made it possible to conduct 18 591 screening studies of clinical material for acute respiratory viral infections (ARVI), natural-focal and acute intestinal infections (AII), as well as the study of 280 water samples for cholera. Introduction of the sequence of operational procedures adapted for work in emergency situations resulted in isolation of 10 Vibrio cholerae O1 ctxA– strains from water bodies. The phased involvement of the mobile group of SAET specialists, and later the MC of the SAET, in combination with the consistent operational target rotation of personnel in order to provide adequate laboratory support for monitoring studies, determined the tactical features of the SAET functioning. Prompt investigation, substantiation of potential and response to realized (actual) epidemiological risks associated with the extraordinary situation made it possible to prevent complications of the epidemiological situation in the territory of the tourist cluster of the Russian Federation.

The review provides concise information on the innate ability of cells of the tularemia pathogen, Francisella tularensis subsp. Holarctica, to resist antimicrobials through a variety of mechanisms, leading to its multi-resistance. In total, taking into account new territories, 120 cases of human infection were registered in the Russian Federation in 2022. Epizootic manifestations of the infection of varying degrees of intensity were detected in 58 constituent entities. Against this background, sporadic cases of tularemia in humans were reported in 18 regions of the country. An outbreak of tularemia occurred in the Stavropol Territory; the disease of mild and moderate severity was found in 76 people. The increased incidence of tularemia persists in the Republic of Karelia with severe cases of the disease in the absence of immunoprophylaxis of this infection in the region. A total of 61 cultures of the tularemia pathogen F. tularensis subsp. holarctica, out of which 20 erythromycin-resistant strains were isolated in the Stavropol Territory. In addition, 8 cultures of F. tularensis subsp. mediasiatica from a silt sample and mites Dermacentor silvarum and Haemaphysalis concinna caught in the Republic of Altai were isolated. On the territory of the Russian Federation in 2022, 930 999 people were vaccinated and revaccinated against tularemia. Based on the analysis of the data obtained in 2022, epidemic complications in 2023 in the form of sporadic cases of the disease among the unvaccinated population are most likely to occur in the territories of the Central Federal District – in the Vladimir, Ryazan and Smolensk Regions; Northwestern Federal District – in the Arkhangelsk Region and the Republic of Karelia; Southern Federal District – in the Volgograd and Rostov Regions. The situation in the North Caucasian Federal District will remain tense in the Stavropol Territory; in the Volga Federal District – in the territories of the Saratov Region, as well as in the Kirov Region and the Republic of Mordovia; Ural Federal District – in Khanty-Mansi and Yamalo-Nenets Autonomous Districts; Siberian Federal District – in certain territories of Omsk, Kemerovo, Tomsk, Novosibirsk, Irkutsk Regions, Altai, Krasnoyarsk Territories; in the Far Eastern Federal District, the most intense epizootic activity of natural tularemia foci is in Primorsky Krai.

The aim of the review was to analyze and assess the epidemiological situation on cholera in the world and Russia in 2013–2022 and to make a forecast for 2023. Over the period of 2013–2022, 500 administrative territories affected by cholera were identified in various regions of 71 countries of Asia, Africa and America (the Caribbean region) with formation of 69 endemic foci in 16, 41 and 12 countries, respectively. In 2022, 1 209 301 cases of cholera were registered in 36 countries of the world. The intensity of epidemic process in Asian countries (Syria, Lebanon) increased. Unfavorable epidemiological situation on the African continent persisted. Epidemics and large outbreaks, which began in 2021–2022 due to emergency situations (ES) of social and natural character, continued. The prediction of the stability of the epidemiological situation on cholera in the territories of constituent entities of the Russian Federation (RF), given for 2022, has been confirmed. In 2022, 43 non-toxigenic strains of Vibrio cholerae О1 were isolated from surface water bodies, 8 V. cholerae nonO1/nonO139 strains – from humans. Similarity of those strains with genetically closely related ones isolated in the course of monitoring in previous years in Russia, Donetsk People’s Republic (DPR) and Zaporozhye Region was demonstrated. In 2023, the risks of importation of the infection into RF are retained. It is associated with the intensification of epidemic processes in Asian, African and Caribbean region countries. The extended border with Ukraine, to where importation of cholera from endemic countries is possible, contributes to increased degree of threat. Bioterrorism is also not excluded. The consequences of a possible cholera epidemic complication in DPR, Lugansk People’s Republic, Zaporozhye and Kherson Regions are exacerbated by social emergencies resulting in disruption of infrastructure, interruptions in water supply, etc. In the absence of implementation of the risks of importation of this infection on the territory of RF, a stable epidemiological situation on cholera will be retained. Detection of non-toxigenic V. cholerae O1 strains (including probability of clonal complexes formation), as well as strains of non-O1/non-O139 serogroups, which can be etiological factors of sporadic cases or outbreaks of diarrheal diseases, in surface water bodies is predicted.

Objective: to analyze the results of blood sera comprehensive study of the local population of the RR, conducted in 2021 to assess the state of natural and zoonotic focus of CHF, WNF, ITBB, tularemia and risk of possible spread of Haemorrhagic Fever with Renal Syndrome (HFRS). Materials and methods: 424 blood serums obtained in 2021 from healthy donors living in 10 administrative territories of the Russian Federation were tested by enzyme immunoassay. Results: in 2021 the detection rates of specific antibodies in the studied areas were: WNF — 9,9 %, HFRS — 4,5 %, ITBB — 2,6 %, CHF — 0,7 %, tularemia — 22,6 %. When comparing the results obtained in 2020 and 2021, the difference in the proportions of seropositive samples is not statistically significant. Conclusions: the study of the immune layer to NFI in selected population groups confirms the circulation of pathogens in RR territory. The monitoring results demonstrate the extensive, mostly combined nosoareals of NFI of viral and bacterial etiology and the contact of the local population with them.

The studies on humoral immune response in the individuals who have undergone COVID-19 and vaccinated with anti-COVID vaccines allows us to assess the development of “hybrid” immunity, which contributes to understanding the mechanisms of its formation from the effector phase to the step of immunological memory. We assessed the relative and absolute contents of B cell populations and subpopulations, development of humoral immunity in the patients who suffered with COVID-19 of varying severity being thereafter vaccinated with “KoviVak” and “Sputnik V”. The study involved volunteers (age 47.3±14.5 years) who beared COVID-19 asymptomatically (n = 32), at moderate severity (n = 21), or had severe form of the disease (n = 12), then being vaccinated with “KoviVak” and “Sputnik V” 6-9 months after their recovery. The groups of vaccinated persons consisted of those who beared severe disease being vaccinated with “KoviVak” (n = 6) or “Sputnik V” (n = 6); moderate cases, vaccinated with “KoviVak” (n = 10) and “Sputnik V” (n = 11); asymptomatic cases vaccinated with “KoviVak” (n = 10) and “Sputnik V” (n = 22). We have determined relative and absolute numbers of B lymphocytes (CD45+CD19+), B1 lymphocytes (CD45+CD5+CD19-CD27-), B2 lymphocytes (CD45+CD19+CD5-CD27-), total population of memory B cells (CD45+CD19+CD5-CD27+), non-switched (CD45+CD19+IgD+CD27+), and switched (CD45+CD19+IgD-CD27+) memory B cells; mature naive B lymphocytes (CD45+CD19+CD27-IgD+), plasmoblasts (CD45+CD19+ CD38+++IgD-CD27+), as well as presence of IgG to S(RBD)-SARS-CoV-2 protein.We have found that the humoral immunity among survivors of COVID-19 of varying severity is expressed for up to nine months. The largest number of volunteers who raised antibodies to SARS-CoV-2 S-protein was registered in the group of seriously ill patients. As soon as 1 month after “Sputnik V” vaccination and until the end of the observation, all the examined subjects in this group became seropositive. 4-5 months after injection of this vaccine, specific immunoglobulins were present in all patients who had asymptomatic or average-severity infection. All volunteers who received “KoviVak” had antibodies to the COVID-19 viral S protein from the beginning to the end of the study. Vaccination, especially with “KoviVak”, contributed to the highest increase, both in relative and absolute numbers of memory B lymphocytes in asymptomatic patients. Less pronounced changes in the content of B lymphocytes in COVID-19 patients who had severe and moderate clinical course may be associated with higher levels of these cells prior to injection of the vaccines. A positive correlation was found between the number of memory B cells and presence of immunoglobulins to the S protein SARS-CoV-2 in all examined patients.

The review presents the basic information available in the literature on the structural proteins of SARS-CoV-2 (S;N;E;M). Issues affecting the importance of these proteins in the pathogenesis, adaptation and life cycle of the virus are discussed. Structural multifunctional proteins are biomarkers of increased contagiousness and pathogenicity of SARS-CoV-2, forming its pathogenetic and adaptive potential. The multifunctionality of the structural proteins of the new coronavirus allows it to respond quickly to fluctuations in the conditions of existence through the use of alternative approaches to implement the mechanisms underlying its pathogenetic potential. Currently, the structure, properties, functions and role of structural proteins of SARS-CoV-2 are being actively studied, which is an actual vector of research that allows us to decipher the mechanisms underlying its high contagiousness, pathogenicity, adaptation, and in the future to evaluate possible ways of forming its new variants and develop a strategy and tactics of emergency response when it appears new strains.The prospects of further study of the structure and properties of structural proteins for solving the priority tasks of the present time on the creation of modern domestic vaccines and effective methods of diagnosis, treatment and prevention of a new coronavirus are noted.The authors analyzed scientific publications from various databases of electronic libraries, such as PubMed, e-library, CyberLeninka, etc.

During more than 50 years, a heterogeneous population of Vibrio cholerae non-O1/non-O139 (NAGs) exists in Rostov region of Russia, whose representatives periodically cause acute human intestinal infections; the last case was registered in 2018. In 2022, a sick child was again revealed in Rostov, from whom 2 NAG subcultures were isolated. Aim of the study: bioinformatics analysis of whole genome sequences (WGSs) of the 2022 clinical NAG isolates, genetic determinants of pathogenicity factors and relevant products. Materials and methods. Isolation, identification of cultures, as well as antibiotic sensitivity were carried out according to the MUK 4.2.3745-22. SNP analysis of WGSs obtained on the MiSeq Illumina platform were analyzed by means of designed software; BioEdit 7.2.5, Vector NTI Advance 11 package, CARD database were used to identify and analyze genes and relevant deduced products. Results. The isolated cultures with identical phenotypic features, PCR-genotypes and results of SNP analysis, were identified as a non-toxigenic NAG. The agent showed sensitivity to chloramphenicol, ceftriaxone, streptomycin, gentamicin, nalidixic acid, ciprofloxacin, ampicillin, amikacin and intermediate resistance to tetracycline, doxycycline, furazolidon and co-trimoxazole. WGSs lacked CTX and preCTX prophages, pathogenicity island VPI, thermostable and cholix toxin genes, pandemic islands VSP-I and VSP-II. The determinants of the type 6 secretion system (T6SS) were not presented completely, which evidenced in favor of the loss of its functionality. An intact T3SS cluster was revealed, which was adjacent to the nan-nag region of the VPI-2 pathogenicity island in the absence of the proximal and distal parts of the latter. Other determinants of pathogenicity factors were revealed: RTX cluster responsible for synthesis of MARTX cytotoxin, genes for hemolysin HlyA, cytotonic toxin Cef, several serine and metalloproteases. The nucleotide compositions of most determinants differed from the prototypes, but their putative products preserved characteristic active domains. The adhesive activity might be provided by mannose-insensitive MSHA-like pili, since the msh-cluster included all the genes necessary for their production, as well as flagella, as both clusters responsible for their assembling were 99% identical to the prototype. From antibiotic resistance determinants only -lactamase VarG gene was found. Conclusion. The NAG strain examined here contains a sufficient set of intact virulence-associated genetic determinants, expression of which could contribute to the development of the disease.

The aim of study was to conduct epizootiological monitoring of natural tularemia foci of the steppe type and investigate epizootic activity in the south-east of the Rostov Region.Materials and methods. An epizootiological survey was carried out on the territory of Remontnensky, Sal’sky and Peschanokopsky districts of the Rostov Region in 2019–2021. To capture and collect mammals, Ixodidae ticks and to study the samples of field material conventional methods were used.Results and discussion. Habitation of 16 species of small mammals, 6 species of Ixodidae ticks has been found. Molecular-genetic analysis of the voles has revealed the presence of the species Microtus arvalis obscurus in the studied area of the region. The circulation of the tularemia agent has been established in the population of common and social voles, forest mouse, hare, rook, Dermacentor marginatus, Hyalomma marginatum, removed from rooks. In May 2020, a high increase in the number of the social vole in the Remontnensky district (up to 21 %), in July 2020 – the common vole in the agrocenoses of the Sal’sky district (up to 33 %) was observed. An extensive epizooty of tularemia was detected in the population of common vole in the south-east of the Rostov Region and in adjacent territories in the Republic of Kalmykia and the Stavropol territory. Two cultures of the pathogen were isolated from the fallen and captured social voles, and four cultures – from the common vole. The isolated strains belong to the Holarctic subspecies of Francisella tularensis EryR. The results obtained attest to the activation of the natural tularemia focus in the south-east of the Rostov Region and its high epizootic activity.

The aim of the study was to retrospectively analyze the range of variability of antigenic properties and genotypic characteristics of Vibrio cholerae R-variant strains atypical in terms of agglutinability.Materials and methods. 169 strains of V. cholerae R-variant with atypical agglutinability have been studied using the “AmpliSens® Vibrio cholerae-FL” test-system. The determination of O1 antigen was carried out using the “Ig-V. cholerae О1/О139 – ELISA/dot-ELISA” reagent kit.Results and discussion. A retrospective analysis of the complex of phenoand genotypic characteristics of strains isolated from surface water bodies in the territories of three former Soviet republics and 13 constituent entities of the Russian Federation in the course of 30-year monitoring and identified upon isolation as nontoxigenic V. cholerae R-variant strains has been performed. Upon re-identification, it was found that the strains belong to both epidemically dangerous (3.0 %) and non-dangerous strains (97.0 %). The range of variability was expressed in their distribution into three groups and consisted in retaining of agglutinability only with cholera RO serum in the first group (34.5 % of strains); the loss of this trait, but the acquisition of the ability to agglutinate in different combinations with O1, Ogawa or Inaba sera – in the second (16.7 %); and also in the loss of agglutinability with all diagnostic cholera sera – in the third (48.8 %). The presence of the wbeT gene in the compared V. cholerae classical R-variant strain does not exclude the presence of the genomic region for O1 antigen biosynthesis in other R-strains, possibly in a modified form, which can be clarified in further molecular-genetic studies. Alternatively, such strains are likely to be attributed to V. cholerae nonO1/nonO139. Strains of V. cholerae R-variant with different amounts of surface antigen (optical density range – from 0.088±0.002 to 1.226±0.003) have been identified. The data obtained can be used for monitoring of cholera in laboratories of regional and federal levels.

SARS-CoV-2 can cause a decrease in the number of lymphocytes and their functional activity. In patients with COVID-19, especially with a severe course of the disease, a decrease in the quantitative composition of the main populations of lymphocytes is recorded. These indicators do not recover for a long time after recovery. However, it is still not known how long the quantitative and qualitative changes in the composition of lymphocytes will last and whether the severity of the infection affects this process. The aim of our study was to assess the quantitative and qualitative composition of the main populations and subpopulations of lymphocytes in patients with a new coronavirus infection of varying severity. 65 patients with a new coronavirus infection were examined. The average age of the subjects was 47.314.5 years. The volunteers were divided into three groups according to the severity of the infection: asymptomatic (n = 21); moderate (n = 32); severe (n = 12). The relative and absolute number of T-lymphocytes (CD3+), T-helper cells (CD3+CD4+), cytotoxic lymphocytes (CD3+CD8+), natural killers (CD3CD16+CD56+), TNK-lymphocytes (CD3+CD16CD56+) and B-lymphocytes (CD45+CD19+) were determined. To calculate the percentage of lymphocytes, whole blood was lysed with OPTILYSE C solution (Beckman Coulter, USA) and stained with monoclonal antibodies CD3+-FITC/CD8+-ECD/CD4+-PC5/CD16+CD56+PE and CD45+-Pacific Blue/CD19+-PC5 (Beckman Coulter, USA). Cytofluorometry was performed on a flow cytofluorometer Navios (Beckman Coulter, USA). The results of our studies showed that there were no statistically significant changes in the relative and absolute number of immunocompetent cells in asymptomatic patients with a new coronavirus infection, compared with the control group. With an average severity of the disease, a decrease in the relative and absolute content of CD3+ and CD8+ lymphocytes was revealed, these indicators were restored to control values six months after recovery. In patients with severe infection, there was a decrease in the relative and absolute number of T cells and cytotoxic lymphocytes. These values remained significantly below normal for six months and returned to normal only seven to eight months after recovery. Also, the volunteers of this group were found to have a decrease in the number of natural killers and TNK cells. Thus, the data obtained by us indicate that pathological changes concerning the relative and absolute number of the main populations and subpopulations of lymphocytes in patients with COVID-19 depend on the severity of the disease. The number of T-lymphocytes, cytotoxic lymphocytes, natural killer cells, that is, populations of cells that play a crucial role in effective antiviral protection, has been reduced in those who have undergone a new coronavirus infection in moderate and severe form. This information can be useful for expanding methodological approaches to the diagnosis, treatment of a new coronavirus infection, as well as measures for the rehabilitation of those who have suffered it.

Objective: formation of a brief overview of data on the main historical stages of the formation and development of the sanitary and epidemiological service in the country as a whole and in the Don region, in particular, as well as on the contribution of Rospotrebnadzor bodies and organizations in the Rostov region to the common cause of ensuring the sanitary and epidemiological well-being of the country in different time periods. Materials and methods: Analysis of archival materials, library collections of institutes and literary sources from databases of electronic libraries e-library, CyberLeninka, etc. Results: The contribution of the Rostov-on-Don Research Anti-Plague Institute and the Rostov Research Institute of Microbiology and Parasitology to the common cause of ensuring the sanitary and epidemiological well-being of the country in different time periods is indicated. Special attention is paid to the issues of effective interaction of Rospotrebnadzor bodies and organizations among themselves and with other healthcare and scientific institutions.Conclusion: Russia has developed a very efficient, operational system capable of effectively addressing issues of ensuring the sanitary and epidemiological well-being of the population.

Background. The ongoing pandemic of a new coronavirus infection (COVID-19) determines the relevance of the analysis of epidemiological patterns of SARS-CoV-2 spread among the population of the Russian Federation.Aim — study of the manifestations of the epidemic process of COVID-19 in the Russian Federation in 2020–2022.Materials and methods. A retrospective epidemiological analysis of the incidence of COVID-19 in the Russian Federation was carried out from 03/30/2020 to 04/24/2022. The data from the Rospotrebnadzor report No. 970 “Information on cases of infectious diseases in persons with suspected new coronavirus infection”, information portal Stopcoronavirus.rf, etc. were used. The presence of SARS-CoV-2 RNA was confirmed by real-time RT-PCR.Results and discussion. The analysis of the manifestations of the epidemic process of COVID-19 in the Russian Federation in 2020–2022 showed the presence of two stages which differed depending on the influence of the biological factor and the ongoing anti-epidemic measures. There was a pronounced trend in the development of the epidemic process, starting from megacities (Moscow, Moscow region and St. Petersburg), which are major transport hubs and centers of migration activity of the population, to the regions of the Russian Federation. The SARS-CoV-2 pathogenicity has been shown to decrease with each subsequent cycle of the rise in the incidence of COVID-19 against the background of the increased contagiousness of the virus.Conclusion. As a result of the study, risk areas (megacities) and risk groups were identified.

The aim of the work was to summarize the experience of the Rostov-on-Don Research Anti-Plague Institute in the organizational and functional response aimed at ensuring the implementation of a complex of on-going and scheduled anti-epidemic (preventive) measures at different territorial levels in the context of COVID-19 pandemic. Stage-wise reassignment of scientific and operational subdivisions of the facility was carried out in a timely manner in a flexible mode for a prompt response to the challenges that arose from community transmission of the new coronavirus infection in the territory of the Russian Federation. It allowed an effective distribution of the forces and assets without damage for specialized functioning in the main areas of scientific and practical activities. Realized was an effective interdepartmental interaction with territorial scientific and practical institutions of the Rospotrebnadzor and specialized medical organizations. Practical, methodological and advisory assistance was provided to personnel of specialized medical institutions within the framework of conversing in-patient facilities into hospitals for the treatment of patients with COVID-19. Priority research to study the level of the humoral and cellular immune response to SARS-CoV-2 among the population of the Rostov Region, the etiological spectrum of the causative agents of community-acquired pneumonia associated with COVID-19, full genome sequencing of SARS-CoV-2 isolates was carried out. Specialists of the task forces reinforced human resources of individual laboratory facilities in Moscow city, the Republic of Crimea and the Rostov Region. Complex objective of effective functioning has been implemented: in an operational mode – participation in anti-epidemic (preventive) measures in the face of changes in the dynamics and intensity of the epidemic manifestations of new coronavirus infection; in scheduled mode – the implementation of activities in the main areas of the scientific work of the organization.

The aim of the work was to summarize the results of cholera monitoring in 2021, to assess current trends in the development of the epidemic process, and to predict the epidemiological situation in the Russian Federation for 2022. It was established that within the period of 2012–2021, 4117264 cases of cholera with the spread of infection across 83 countries on all continents were registered in the world and there was a downward trend in the incidence in Asia and Africa. The dynamics of monthly morbidity in 2021 was associated with emergencies as factors of epidemiological risk. Epidemics and outbreaks of cholera were documented against the background of COVID-19 pandemic and laid a double burden on healthcare systems. At the same time, based on the overview of the results of cholera monitoring in the constituent entities of the Russian Federation, it was shown that the forecast of epidemic well-being given for 2021 was fully justified. It has been determined that the increase in the number of non-toxigenic strains of Vibrio cholerae O1 (67) isolated from water bodies compared to 2020 (25) is mainly due to the appurtenance of a number of isolates to clonal complexes. The study of phylogenetic relation has demonstrated that the detection of strains with genotypes which were previously identified in the isolates evidences the persistence potential. The identification of strains with new genotypes, which were earlier established in the strains circulating in other territories, pointed at the possibility of the occasional importations. The forecast of the epidemiological situation on cholera in Russia for 2022 is associated with the continuous existence of risks of introduction. If these epidemiological risks are not realized, a favorable epidemiological situation is predicted regarding this infection in the country. It is expected that the detection of epidemiologically insignificant strains of V. cholerae O1 in environmental water bodies, along with their clones and/or clonal complexes, will remain, including strains that may be an etiological factor in sporadic cases or outbreaks of disease.

In this review, methods for isothermal amplification of nucleic acids are considered and analyzed, in particular, loop isothermal amplification of DNA and RNA (LAMP/RT-LAMP), helicase-dependent amplification (HDA) and recombinase polymerase amplification (RPA). The advantages and disadvantages of each of the techniques are described. The possibility of their application in the molecular diagnostics of infectious diseases is evaluated. A brief review of the literature on the use of LAMP, HDA, RPA in the diagnostics of viral, bacterial infections and diseases of protozoal etiology was conducted. It has been shown that the LAMP method has a number of advantages over other diagnostic methods: high efficiency, specificity, simplicity, turnaround time and minimum requirements for instrument equipment. As a result, it is concluded that loop isothermal amplification is a promising method for detecting the DNA/RNA of various pathogens. The data on the introduction of the LAMP method in the diagnostics of particularly dangerous bacterial and viral infections, including for the detection of RNA of a new coronavirus infection (SARS-CoV-2) in clinical samples, are presented.

Objective: To analyze the results of epizootic monitoring of natural foci of particularly dangerous infections common to humans and animals in Rostov Oblast to establish their activity.Materials and Methods: The data of epizootic monitoring conducted by zoologists; the results of laboratory research of field material obtained in natural foci of infectious diseases. Descriptive, zoological, genetic, serological methods, and retrospective epidemiological analysis were used.Results: The results of the conducted epizootic monitoring showed the presence in Rostov Oblast of natural foci of particularly dangerous infectious diseases common to humans and animals. While the natural focus of the plague is in a depressed state and does not show activity, in the foci of tularemia, West Nile fever (WNF), Crimean hemorrhagic fever (CHF), ixodic tick-borne borreliosis (ITB), hemorrhagic fever with renal syndrome (HFRS), Q fever, Batai fever, California serogroups, Syndbis revealed the antigens of these pathogens in biological material obtained from small mammals and blood-sucking insects, which indicates the epizootic activity of these foci. In the natural foci of WNF, CHF, ITB, HFRS, cases of these disease among the population were recorded, which confirms the epidemic activity of these foci.Conclusion: The obtained results of epizootic monitoring over the period from 2008 to 2020 emphasize the relevance and necessity of continuing these studies in natural foci in Rostov Oblast.

The data obtained during previous epidemics caused by coronaviruses, and current pandemic indicate that assessing the role of certain immune interactions between these viruses and the microorganism is the main pre-requisite for development of diagnostic test systems as well as effective medical drugs and preventive measures. The review summarizes the results of studying patho– and immunogenesis of SARSCoV, MERS-CoV, and SARS-CoV-2 infections. These coronaviruses were proven to suppress development of adaptive immune response at the stage of its induction, affecting the number and functional activity of lymphocytes, effectors of cellular immunity, causing impairment of lymphopoiesis, apoptosis and «depletion» of these cells, thus leading to longer duration of the disease and increased viral load. Information about the role of cellular immunity in development of immune response to coronaviruses is presented. It was proven that the causative agents of SARS, MERS and COVID-19 trigger adaptive immune response in the microorganism according to both humoral and cellular types. Moreover, the synthesis of specific immunoglobulins does not yet point to presence of protective immune response. Activation of the cellular link of immunity is also important. A high degree of antigenic epitope homology in SARS-CoV, MERS-CoV and SARS-CoV-2 is described, thus suggesting an opportunity for cross-immunity to coronaviruses. The review addresses issues related to the terms of specific memory immune cells to SARS-CoV, MERS-CoV and SARS-CoV-2, and their role in providing long-term protection against these infections. Given that specific antibodies to SARS and MERS pathogens persisted for a year, were often not detected or briefly registered in patients with mild and asymptomatic infections, we can talk about important role of the cellular immune response in providing immunity to these coronaviruses. It was shown that, in contrast to antibodies, the antigen-specific memory T cells were registered in patients with SARS virus for 4 to 11 years, and Middle East Respiratory Syndrome – up to two years. Further research is needed to determine presence and number of memory T cells in COVID-19. A comparative analysis of data obtained during previous epidemics with respect to formation of adaptive immunity to coronaviruses. Description of proteins and epitopes recognized by human T lymphocytes will be useful in monitoring immune responses in COVID-19 patients, as well as in developing informative tests to study T cell immune response to SARS-CoV-2 and new preventive drugs.

Background. At the height of the novel coronavirus infection, the risk of fungal coinfection increases due to a decrease in the immune status of patients and massive antibacterial therapy, which leads to a complication in the course of the underlying disease and increases the risk of an unfavorable outcome. Therefore, it is necessary not only to identify all associates that cause the infectious process, but also to determine their sensitivity to antibacterial and antifungal drugs in order to select an adequate treatment regimen for a patient.The aim of the study was to investigate the species composition of fungal associates in corona positive and corona negative patients with community-acquired pneumonia (CAP), as well as to determine the spectrum of sensitivity/resistance of yeasts and yeast-like fungi to antimycotic drugs.Material and methods. The species composition of the fungal microflora in sputum samples from 723 patients with CAP, sent from a health care facility in Rostov-on-Don, was investigated. The isolated cultures were identified using bacteriological and mass spectrometric methods. The sensitivity of yeasts to antimycotic drugs was determined by disk-diffusion method.Results. It has been established that yeast and yeast-like fungi were present in sputum samples in 31–32% of patients with CAP in etiologically significant quantities. 10 different types of yeast and yeast-like fungi were identified. Candida albicans was the predominant species in terms of the number of isolated cultures (83%). A re-examination of corona positive patients after their hospital stay revealed a tendency towards an increase in the number and intensity of manifestation of candidal lesions. Moreover, a change in Candida species has been registered, which entails a change in their sensitivity to antifungal drugs. A high percentage of strains resistant to fluconazole was identified after determining the sensitivity of fungi to antimycotics.Conclusion. The data obtained demonstrate that yeast and yeast-like fungi are the dominant associates in complicated forms of CAP. In this regard, it seems appropriate to provide individual microbiological support to patients during their treatment with the identification of all pathogens.

Objective of the study was to investigate biological properties and genetic characteristics of tularemia agent strains isolated from natural foci of the Rostov Region in 2020.Materials and methods. Field material from natural foci of the Rostov Region was examined by serological, bacteriological, biological, and molecular-genetic methods. Cultural-morphological, biochemical, antigenic and pathogenic properties of isolated cultures were studied. Protein profles were obtained through MALDI-TOF MS using mass spectrometer Autoflex speed III Bruker Daltonics and Flex Control of Biotyper software. The genetic characteristics of the strains were determined by VNTR and INDEL typing and SNP analysis.Results and discussion. Six strains of tularemia pathogen were isolated from mouse-like rodents using biological method. The investigation of their biological features and data of PCR analysis and INDEL typing with canonical markers showed that all strains are typical representatives of the Francisella tularensis subsp. holarctica biovar EryR. VNTR typing by six genetic loci revealed that all strains belong to four individual genotypes. The strain isolated in 2020 in the Salsky district was identical to the strain which was isolated in the same area in 1989. Based on the whole genome sequencing of two strains, we established that they are closest to the cultures isolated in Turkey (2009, 2012) and Khanty-Mansiysk (2013) by the studied set of SNP markers. Thus, we found that both identical (or closely related) clones of the tularemia agent and new strains with unique genotypes which previously were not described for the Rostov Region can circulate in natural foci of this region for a long period of time.

Objective: To compare the genomic diversity of SARS-CoV-2 strains that were spread in the Rostov region and the Republic of Crimea in the period from March to June 2021.Materials and Methods: A total of 194 samples were sequenced and 186 genovariants were recognized among them using the Pangolin program. Multiple alignment was performed and dendrograms were constructed for the samples belonging to the alpha and delta genovariants.Results: Changes of the predominant genovariants were revealed for territories of the Rostov Region and the Republic of Crimea from March to June. An increasing percent of the alpha variant was observed in both regions during the spring followed by the rapid emergence of the delta variant, which became predominant in June.Conclusion: It was shown that alpha variant samples from the Rostov region share a pool of common mutations, while in contrast, alpha variant samples from the Republic of Crimea are closer to those sampled from Moscow and Moscow region. At the end of May, the delta gene variant begins to be revealed, which is rapidly replacing other lines in all the territories considered in this study.

Purpose. A dynamic comparative analysis of the results of identification of Vibrio cholerae (V. cholera) isolates from water and human specimens isolated during the monitoring of cholera throughout the Russian Federation in 2013–2019.Materials and methods. Total 385 strains of V. cholerae O1 serogroup (including one toxigenic V. cholerae O1 El Tor Inaba — Rostov region, 2014) and the R-variant from environment objects were identified in the territory of 21 regions of the Russian Federation.Results. It was found that 91% of the strains were isolated in 7 regions of the Russian Federation: Republic of Kalmykia, Krasnodar Krai, Transbaikal Krai, Khabarovsk Krai, Primorsky Krai, Rostov region and Irkutsk region. 2.3% of strains were atypical in their agglutinability, and 75.3% of strains had atypical phagosensitivity. Phagotypes were identified for 13.2% of strains isolated in 11 administrative territories. Phageotype 11 included 48.8% of the strains isolated mainly in the Transbaikal Krai. Non-toxigenic strains of V. cholerae nonО1/nonO139 (n = 46) were isolated from 43 patients with acute intestinal infections and otitis in 8 regions of Russia. PCRtyping of 377 non-toxigenic V. cholerae strains demonstrated that they belong to 13 clusters and 71 genotypes. Strains with unique genotypes (probable cases of importation) and with the same genotypes repeatedly isolated in different years in one or several territories of the Russian Federation were identified, indicating the prevalence of strains in environment throughout the country.Conclusion. The results allowed us to characterize the epidemiological situation of cholera in Russia (in terms of the environment contamination with V. cholerae O1) as unstable, but not significantly changed over the past 7-year period. These data are important for substantiating the forecast for further development of the epidemiological situation.

Aim of the work – to assess the epidemiological situation on cholera in 2020 and to make a forecast for 2021 based on the monitoring data and analysis of morbidity around the world for the period of 2011–2020. During the period between 2011 and 2020, 4 413 988 cases of cholera were recorded in 97 countries of the world with a general trend towards a decrease in the incidence (coefficient of accuracy of approximation R2 – 0.5705). However, due to the continuing epidemic manifestations of cholera in the endemic countries of Asia, Africa and America, the epidemiological situation on cholera on these continents was characterized as unfavorable in 2020. The emergence of a new “post-Haitian” lineage was observed among epidemically hazardous strains of Vibrio cholerae O1. In 2020, no epidemically dangerous strains of V. cholerae O1, O139 were isolated from humans on the territory of the Russian Federation. 25 non-toxigenic V. cholerae O1 El Tor strains were isolated from environmental objects, eight out of which (ctxA-, tcpA+), according to PCR-INDEL typing and SNP analysis of sequences, belonged to the clonal complex. The results of the analysis of biological properties and phylogenetic relations between the isolated non-toxigenic strains provided the basis for considering the epidemiological situation on cholera in Russia in 2020 as a stable one and a similar forecast of its development in 2021. At the same time, the possibility of importation of this infection from endemic countries cannot be ruled out, as well as the need to carry out a complex of differentiated anti-epidemic (preventive) measures within the framework of the state sanitary-epidemiological surveillance in order to localize and eliminate the imported focus and avoid the spread of the infection.

The first coronavirus NСoV-B814 was isolated from humans in 1965 and did not survive to the present time. For a long time, it was believed that coronaviruses were not pathogenic to humans. They were not included in the list of particularly dangerous infections and represented a serious problem exclusively in veterinary medicine. But in 2002, after the SARS outbreak, scientists’ opinions changed. A new subtype of the coronavirus called SARS-CoV penetrated the human population. In 2012, it was possible to discover natural foci of Middle East Respiratory Syndrome. The epidemic of a new coronavirus infection that emerged in late 2019 and early 2020 attracted the attention of scientists around the world. The priority was a detailed and close study of all the varieties of this virus. This review describes seven types of coronaviruses that can cause emergencies in populations around the world.

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.

By August 2020, more than 850000 cases of new coronavirus infection (COVID-19) caused by SARSCoV-2 were confirmed in the Russian Federation, with the Rostov Region as one of the ten most affected regions in Russia. The spread of the disease is largely determined by the state of population immunity in a certain area. Our research focuses on specific humoral immune response and estimates the level of herd immunity to SARS-CoV-2 virus among the population of the Rostov Region.Materials and methods. The study involved 3,048 people; the volunteers participating in the study were divided into seven age groups. The content of antibodies to SARS-CoV-2 was determined applying ELISA using a kit for the analysis of human serum or blood plasma for the presence of specific IgG to the nucleocapsid of the SARS-CoV-2 virus, manufactured by the State Scientific Center of Applied Microbiology and Biotechnology (Obolensk) in accordance with the instructions for use.Results and discussion. The assessment of seroprevalence to SARS-CoV-2 in the Rostov Region showed that the proportion of people positive for IgG to the new coronavirus was 16.5 %, the range of seropositive individuals in the general population was between 13.9 % and 19.1 % (p

Objective: comparative study of the etiological structure of community-acquired pneumonia in SARSCoV-2 “+”and SARS-CoV-2 “-“ patients who sought help from medical organizations in the Rostov Region.Materials and methods. Biological material from 508 patients diagnosed with community-acquired pneumonia who were on outpatient treatment or in hospitals in Rostov-on-Don was studied. Verification of respiratory viruses, including SARS-CoV-2 RNA, as well as M. pneumoniae, C. pneumoniae, and L. pneumophila was performed by polymerase chain reaction in nasopharyngeal smears. Bacteriological analysis of sputum was carried out using differential diagnostic media, identification of isolated pathogens was carried out using time-of-flight mass spectrometry on Autoflex (Bruker Daltonics) with BioTyper 3.0 software.Results and discussion. During the spread of a new coronavirus infection in the Rostov Region, the main etiological agent of community-acquired pneumonia is the new SARS-CoV-2 coronavirus. Specific character of pneumonia in patients with laboratory-confirmed COVID-19 is a higher incidence of mixed infection of both viral and bacterial etiology. Against the background of detection of a new coronavirus infection in patients with pneumonia, cases of detection of other types of coronaviruses have been registered (HKU-1,OC43, HL-63 and 229Е). The most common etiological agent of bacterial pneumonia in patients was Streptococcus spp., both in patients with COVID-19-associated pneumonia and in patients who tested negative for SARS-CoV-2. Coronavirus patients represent a high risk group for the development of mycotic lung lesions.

Purpose: to analyze the epidemiological situation for a new coronavirus infection (COVID-19), to identify some regional features of the Rostov region that contribute to spread of infection.Materials and methods: when assessing the epidemiological situation for a new coronavirus infection in the Rostov region, we used information provided by the Department of the Federal service for supervision of consumer protection and human welfare in the Rostov region. Processing of statistical data was performed by means of generally accepted method.Results: the spreading of a new coronavirus infection in the Rostov region is uneven in nature. When differentiating the territories of the region we identified groups of municipalities with a very high, medium and low number of patients. The administrative territories division of the Rostov region into the “Rostov urban agglomeration” and cluster of municipalities in which pronounced factors and conditions determining the “pendulum” migration of the population are absent, allow analyzing the specific features of the region and identification of territory with the highest risk of epidemic process intensification of a new coronavirus infection.Conclusions: the carried out differentiation of municipalities made it possible to identify and analyze some territorial features of the Rostov region, contributing to the spread of a new coronavirus infection. The obtained results could be used for development of measures aimed at reducing intensification of the epidemic process COVID-19 in condition infection.

Relevance. The conceptual task of epidemiological surveillance as part of the sanitary protection of the territory of the Russian Federation (RF) from the importation and spread of diseases that pose a danger to the population at the present stage is to identify potential risks of a sanitary and еpidemic emergency and prompt response if they occur. Epidemic manifestations of diseases caused by new respiratory viruses, in most cases, cause a crisis in public health, which indicates the need for a comprehensive study of the features of their course, determination of criteria for the potential risk of an emergency of an еpidemic nature, which will make it possible to timely organize a complex of anti-epidemic (preventive) measures. Aim. Study, systematize and stratify the features of the atypical course of the epidemic process of acute respiratory viral infections caused by new variants of the pathogen in a city with a population of more than one million people. Materials and methods. The study used retrospective data on infectious morbidity in different age groups from government reports for the period 2015–2020, data from annual forms No. 2 of the federal state statistical observation for the period 2009–2020. Rospotrebnadzor Administration for the Rostov Region, Center for Hygiene and Epidemiology in the Rostov Region. Statistical data processing was carried out by a generally accepted method. Results. The analysis showed that the periods 2009–2010, 2015–2016, 2020–2021 had significant changes in the epidemic process in relation to its typical long-term course with a predominance in the structure of the incidence of ARVI, including influenza and new coronavirus infection, of various age groups for each period, an atypically severe infectious process and an increase in the number of community-acquired pneumonia. Moreover, in the periods 2009–2010, 2015–2016. Influenza A (H1N1) pdm09 virus was dominant in the etiological structure, in 2020–2021 – the causative agent of the new coronavirus infection SARS-CoV-2. Thus, the features of the epidemic (against the backdrop of a pandemic) spread of ARVI in Rostov-on-Don, established as a result of a retrospective analysis, made it possible to differentiate the main-external and internal-risks of the formation of emergencies of an еpidemic nature associated with new respiratory viruses in a city with a population of more than one million people.

Objective of the study was to monitor the spread of cholera in the world, in the CIS countries and in Russia with an assessment of risks and emergencies that contribute to the activation of the epidemic process. Despite the downward trend in the global incidence rate of cholera during the period between 2010 and 2019, epidemics and major outbreaks occurred in 96 countries. WHO has reported 2013 imported cases of cholera to countries in Asia, the Americas, including the Caribbean, Europe, and Australia with Oceania; cholera-endemic administrative territories are identified in 24 countries. According to WHO, cholera burden reduction in Asia and Africa is associated with large-scale vaccination. During epidemiological surveillance of cholera, 705 strains of V. cholerae O1 and O139 serogroups were isolated from surface reservoirs in 26 constituent entities of the Russian Federation, including 10 strains of V. cholerae O1 ctxA+tcpA+, 35 strains of V. cholerae O1 ctxA–tcpA+, 655 strains of V. cholerae O1 ctxA–tcpA– , and five strains of V. cholerae O139 ctxA–tcpA–. Identification of strains with unique, previously unknown INDEL genotypes testifies to their imported nature. The forecast for cholera in the world for 2020, given the proven high degree of epidemic process activation at the expense of social and environmental risks caused by emergencies of different origin, the presence of endemic foci, infection import and other risk factors is unfavorable. For Russia, the forecast for cholera will be determined by the presence of external risks created by the ongoing 7-th pandemic, possible importation of infection to constituent entities of the Russian Federation that differ by the types of epidemic manifestations.

Background. Plague is an especially dangerous natural focal infectious disease belonging to a group of quarantine infections. There are eleven natural plague foci in Russian Federation. In Republic Tyva plague endemic territories include Ovyur, Mongun-Taigin and Tes-Hem areas where Y. pestis strains are intermittently isolated from Citellus undulates. Population living at the territory of the natural foci get immunoprophylaxis against plague at complication of epizootic and epidemic conditions.This paper presents the results of monitoring indicators of the immune status of people vaccinated with the plague vaccine living in the territory of the Tuva natural focus.Materials and methods. The study involved 76 volunteers who had not previously been vaccinated. The study included the determination of production IFN-γ, IL-4, TNF-α by blood cells, titers of specific IgG antibodies to the capsule F1 antigen of the Yersinia pestis, and concentrations of immunoglobulins in serum blood, as well as immunophenotyping of blood lymphocytes.Results. In the course of a comprehensive immunological study, features of the development of cellular and humoral reactions in people living in the territory of the Tuva natural plague focus were established in the first months after vaccination. Changes in the concentration dynamics of the main classes of immunoglobulins were accompanied by an increase in the level of specific IgGs to the F1 within 6 months after immunization. In the same period, a significant increase in the production of cytokines, as well as significant changes in terms of the subpopulation composition of the vaccinated blood.Conclusion. It is necessary to note the importance of studying of the human immune status in 1–3 months after plague vaccination as this period coincides with potentially dangerous season from epidemiological point of view. Nevertheless, much important role for improvement of tactics of the specific prevention measures plays the data received after the revaccination.