Vol 100, No 4 (2023)

Background. Constant assessment of the dynamics of the main characteristics of the epidemic process is the basic function of epidemiological surveillance of infectious diseases. The search for factors that determine changes in the characteristics of the epidemic process makes it possible to develop timely management decisions and reduce the risk of an increase in the scale of the pandemic. Moscow is the main centre of attraction for the population of other Russian regions with the most complex structure of social links and the highest population density.

The purpose of the study is to identify factors that potentially determine the trends of observed changes using a molecular epidemiological analysis of the main characteristics of the epidemic process of a new coronavirus infection (COVID-19).

Materials and methods. For the analysis, the data of Russian national genome sequence database of SARS-CoV-2 virus (VGARus) were combined with information on morbidity and mortality presented at the official internet resources “стопкоронавирус.рф” and Yandex DataLens, the dynamics of vaccination, COVID-19 disease incidence and hospitalization from the portal Gogov.ru. A multicentre retrospective observational epidemiological study was conducted to examine the sex and age structure of hospitalised patients. Anonymized case histories of patients with COVID-19 collected at different follow-up periods in the institutions of Moscow (41,561 cases) served as a source of data for the sex and age structure analysis.

Results. We identified 11 periods with significantly different complex epidemiological characteristics. A decrease in the incidence among young people of working age during the period of restrictive measures was revealed. In 3 out of 11 worsening of the epidemic situation coincided with the beginning of the circulation of a new genetic variant of the pathogen COVID-19 (variants Wuhan, Delta, Omicron). A decrease in the incidence in the summer period was noted, regardless of the circulating genetic variants.

Conclusion. A significant part of the observed dynamics of the characteristics of the epidemic process in Moscow can be explained by the properties of the pathogen, seasonality and dynamics of magnitude of the herd immunity. The influence of the dynamics of the herd immunity indicators on the course of the epidemic process is to be studied further.

Introduction. At present, it is important to study the interaction of Staphylococcus aureus with human innate immunity cells under conditions of ex vivo bacteremia modeling, but not only in experiments with phagocytes previously isolated from the blood.

Purpose: comparative assessment of changes in the phenotype, intensity of aurophilic degranulation, death and lysis of neutrophils in whole blood samples from apparently healthy donors following the addition of live and killed microbial cells of S. aureus ATCC 6538 (209-P).

Materials and methods. Bacteremia was modeled by adding microbes to whole blood (with heparin) at doses ranging from 10⁸ to 10¹ mc/ml. The bactericidal effect was determined at different time points of blood incubation at 37°C (for 6 hours) by the microbiological method. The blood leukocyte immunophenotyping was performed using flow cytometry according to the Lyse/No-Wash protocol to determine the expression of markers of azurophilic degranulation (CD63), early apoptosis (CD95) on the surface of neutrophilic granulocytes (NG) and cell adhesion (CD62L), as well as to assess the surface expression density of the molecular trigger of netosis FcᵧRIIIb (CD16) and tyrosine protein phosphatase (CD45), which is a regulator of FcR-mediated cell signaling during phagocytosis and netosis. The presence of degenerative changes in NG was confirmed by microscopy in the analysis of blood smears stained according to Romanovsky–Giemsa.

Results. Significant differences were revealed in the response of human blood NG to live and killed S. aureus cells according to the studied phenotypic parameters. Only live microbes triggered azurophilic degranulation in NCs and stimulated, starting from 2 h incubation, the appearance of a large number of NG with the CD95⁺ phenotype in the blood. In addition, live bacteria induced in phagocytes twice as much functional rearrangement in terms of CD45 expression. They induced a rapid decrease in the density of CD16 expression on NG and activated NG lysis in the blood with an intensity depending on the initial microbial concentration. Following 6 h incubation at concentrations of more than 10⁵ mc/ml, flow cytometry detected the presence in the blood of a population of low density neutrophils characteristic of sepsis (Low Density Neutrophils — with the CD63⁺CD16^low phenotype), whose cells are prone to spontaneous autolysis (netosis).

Conclusion. Under the conditions of ex vivo modeling of bacteremia, various strategies of human blood neutrophils in the implementation of the mechanisms of protection of the macroorganism from infection were evaluated, and the prospects of using the obtained information to identify individuals at high risk of developing staphylococcal sepsis were determined.

Background. The cause of dengue fever’s endemicity is vector larvae density, with Aedes aegypti as the prime vector. Bandung municipality is a high dengue fever endemic area. Hence, studying the habitat characteristics of the Aedes mosquito is essential to controlling the populations of mosquitos.

Purpose. This study aimed to identify the aedes larvae breeding sites and the relationship between the breeding risk index, hygiene risk index, maya index, and the existence of larvae with the incidence of dengue fever.

Method. The design used in this research was a cross-sectional survey. The sampling technique used simple random sampling. The quantity of the sample was 544 directly observed houses.

Results. The entomological parameters obtained were house index (23.89%), container index (7.81%), Breteau index (50.73%), and larva free number (76.10%). The breeding risk index, hygiene risk index, and maya index are in the low category. The chi-square test conveyed that the breeding risk index, maya index, and the existence of larvae were significantly associated with the incidence of dengue fever.

Conclusion. The entomological index may influence the high incidence of dengue fever. These findings and results may help the authorities to improve mosquito nest eradication in attempts to prevent dengue transmission.

Acute intestinal infections caused by Escherichia coli affect the gastrointestinal tract, leading to development of diarrheal syndrome, intoxication, and, in some cases, generalization of the pathological process. Diarrheagenic E. coli (DEC) strains differ from non-pathogenic (commensal) strains by the presence of specific virulence genes, pathogenesis characteristics, clinical and epidemiological manifestations of the diseases they cause. Based on the virulence determinants, 6 pathogenic DEC groups are distinguished: enteropathogenic, enterotoxigenic, enteroinvasive, shiga toxin-producing, enteroaggregative, diffusely adherent E. coli strains. The strains of each pathogenic group have distinct pathogenic mechanisms responsible for inflammatory processes in different compartments of the human intestine, which are clinically manifested as diarrheal syndrome. This paper presents a review of current scientific publications on epidemiology, pathogenesis, genetic properties, and antigenic characteristics of pathogenic E. coli. Although DEC biological properties have been extensively studied, many aspects require deeper insights to develop effective laboratory-based diagnostic techniques, treatment methods, epidemic control measures, and prevention strategies against E. coli infections.

Meningococcal infection (MI) refers to anthroponoses; is an acute infectious disease with an aerosol transmission mechanism, characterized by various forms of the infectious process: from local (nasopharyngitis) and asymptomatic infections to generalized forms of invasive infection with the development of meningococcemia and meningitis. The causative agent of MI is meningococcus (Neisseria meningitidis) that belongs to the pathogen risk group 2. Preventive vaccination against MI is included in the calendar of preventive vaccinations according to epidemic indications. The problem of MI retains a great medical and social significance for Russian health care due to the continuing high rates of associated mortality, disability, high costs of treatment and rehabilitation. Vaccines against five of the six main N. meningitidis serogroups have been registered worldwide. Serogroup X vaccine is under development. Recently, there has been an increase in the heterogeneity of the meningococcal population due to serogroups W, Y, and X. The polysaccharide vaccines developed in Russia have restrictions on their use, and there is no full-cycle production of meningococcal conjugate vaccines in the Russian Federation. Given the above, the development and registration of new vaccines against MI is an urgent task.

The purpose of this work is to analyze the current state of development of vaccines for MI prevention. Currently, depending on the production technology, the following types of meningococcal vaccines are available: polysaccharide, conjugated, based on outer membrane vesicles (OMV), protein and based on synthetic polysaccharides. Serogroup-targeted meningococcal vaccines are effective in reducing the public health burden of invasive MI. Polysaccharide conjugate and protein/OMV vaccines are among the most promising vaccines for most invasive meningococcal serogroups. In modern conditions, with the progress in technologies for future polysaccharide conjugate vaccines, new opportunities are opening up for the use of such approaches as chemical/enzymatic synthesis, improved characteristics of the carrier protein, and site-specific conjugation. The development of a single vaccine against the main invasive meningococcal serogroups, rather than its individual antigenic variants, does not lose its relevance. It is timely to develop in the near future a vaccine against N. meningitidis serogroup X, which was previously a rare cause of sporadic meningitis, but has caused outbreaks in various African countries in 2006–2010 and in recent years.