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Problems of Particularly Dangerous Infections

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No 1 (2023)
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REVIEWS

6-16 3536
Abstract

The aim of this review is to predict the incidence of tick-borne viral encephalitis (TBVE) in the Russian Federation for 2023 based on analysis of the epidemiological situation on TBVE during 2012–2022. Over the decade, the highest incidence of TBVE was registered in the Siberian, Volga and Ural Federal Districts. In 2022, the Ural Federal District took the second place, the share of the North-Western one decreased by almost two times. Ranking of territories according to the rate of TBVE incidence at the level of constituent entities has made it possible to attribute 16 of them to the group of regions with a high epidemic risk, 14 – to medium epidemic risk, and 18 – to a low epidemic risk. In 2022, the incidence of TBVE in Russia increased by 1.9 times compared to 2021, and amounted to 1.34 0/0000. Despite the increase in the incidence of TBVE in 2022, a significant downward trend has been retained. The rate of infection of ticks removed from humans in 2022 was below the long-term average values. PCR and ELISA were applied for tests. Infection rate of ticks from environmental objects when studied by PCR was higher than the multi-year average values, and lower when studied by ELISA. In 2022, 3.5 million people were immunized against TBVE (vaccinated and revaccinated). Emergency immunoprophylaxis with immunoglobulin covered 24.5 % of the people affected by tick bites (children accounted for 34.3 %). The forecast for TBVE incidence in Russia in 2023 remains favorable. It is expected to be reduced to (0.83±0.298) 0/0000. However, there was not only an increase in the number of TBVE cases, but also the proportion of clinical manifestations of the disease, as well as lethal outcomes among those who suffered from tick bites in 2022. If this pattern holds, the incidence of TBVE in 2023 will be higher than predicted, especially in the constituent entities where the share of individuals with manifest forms among those who suffered from tick bites has increased greatly.

17-26 791
Abstract

Bacterial ghosts are intact walls of bacterial cells that are relieved of their contents through pores formed by mild biological or chemical methods. Methodology for generating bacterial ghosts increases the safety of killed vaccines while maintaining their antigenicity through milder preparation procedures. Moreover, bacterial ghosts can simultaneously carry several antigens or plasmid DNAs encoding protein epitopes. In recent years, there has been a growing interest in the development of prototype vaccines and systems for delivery of biologically active substances based on bacterial ghosts. This review discusses the progress in the development of this type of medications over the last years. Various methods of obtaining bacterial ghosts, their advantages and limitations are considered. The phage-mediated lysis of bacteria, molecular manipulations with lysis genes, difficulties encountered in scaling the biotechnological production of bacterial ghosts, and ways to overcome them are described in detail. The use of bacterial ghosts as alternative killed vaccines, adjuvants, recombinant antigenic platform, carrier of plasmid DNA by the models of pathogens of particularly dangerous infections of bacterial etiology is investigated.

27-36 872
Abstract

Nipah virus (Nipah virus, NiV) is a representative of the genus Henipavirus of the Paramyxoviridae family, the causative agent of a dangerous infectious disease with a wide range of clinical manifestations – from an asymptomatic (subclinical) form to severe encephalitis with fatal outcome. Despite the fact that the disease caused by this virus is registered only in the countries of Southeast Asia, the possibility of importing the pathogen to non-endemic territories is not excluded. Also, this pathogen is able to infect not only a large number of people, but also animals, causing serious diseases and significant economic damage, posing both, a medical and veterinary problem. This review presents the data available in the modern press on the structure and classification of the Nipah virus, possible cycles of its transmission, spread, methods of indication and identification in clinical and biological material, as well as the effectiveness of their use depending on the timing of the onset of the disease and available commercial diagnostic and preventive drugs.

37-47 627
Abstract

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.

48-55 722
Abstract

This paper describes the current situation on highly pathogenic avian influenza virus in 2022 and provides forecast of the possible further spread of avian influenza in Russia. In 2022, the circulation of a wide variety of highly pathogenic avian influenza virus subtypes, which have epizootiological and epidemiological significance, was recorded in the world. Outbreaks caused by highly pathogenic avian influenza virus were reported in over 60 countries. In addition, human infections with influenza viruses of the A(H5Nx) and A(H9N2) subtypes were registered. There was a large-scale epizootic which affected more than 10 regions of the European part of Russia and the Russian Far East in 2022. Outbreaks among wild birds and poultry were caused by the highly pathogenic influenza virus A(H5N1) of the clade 2.3.4.4b, at the same time genetic and antigenic diversity was observed among viruses circulating in Russia. Thus, an essential geographical role of the territory of Russia in the global spread of avian influenza virus has been shown once again, which highlights the importance of continuous avian influenza virus surveillance in the country.

56-66 1707
Abstract

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.

67-74 642
Abstract

The aim of the work was to assess the epidemic situation on plague in the world and epizootic activity of natural plague foci of the Russian Federation in 2022. Following the implementation of comprehensive preventive interventions plans, there was a decrease in the epizootic activity of the Gorno-Altai high-mountain and Tuva mountain natural foci, the cessation of plague epizootics in the Central Caucasian high-mountain focus. The total area of epizootics in the Russian Federation in 2022 reached 248.3 km2, which is 7 times less than in 2021. Infected animals were not found in the Tersko-Sunzhensky low-mountain, Dagestan plain-piedmont, Caspian North-Western steppe, Volga-Ural steppe, Trans-Baikal steppe, Volga-Ural sandy, Caspian sandy, East Caucasian high-mountain natural foci. Persistence of tense epizootiological situation in 2023 is predicted for the territory of the Altai Republic and the Republic of Tuva. The prospects of using the GIS portal of the Russian Anti-Plague Institute “Microbe” of the Rospotrebnadzor for an operational assessment of the actual epidemiological situation in natural plague foci are substantiated.

75-84 1945
Abstract

The review presents an analysis of West Nile fever (WNF) epidemiological situation in the Russian Federation in 2022 and the summarized results of monitoring over the pathogen. The following features of the WNF epidemic process in Russia are outlined: the decrease (by 4 times) in the incidence rates compared to the long-term average values against an extremely extensive nature of manifestations (16 constituent entities in 6 federal districts), including the detection of local cases in 5 new territories (Tver, Tambov, Vladimir Regions, Khanty-Mansi Autonomous District, and Karachay-Cherkess Republic), predominant registration of incidence in the Central Federal District (51 %), early start and termination of the epidemic season. There is a decrease in the proportion of neuroinvasive forms in the structure of incidence, prevalence of females and the age group of “60 years and over”, as well as record rate values of people infected at the place of residence in cities, which is associated with the peculiarities of case detection, namely, screening examinations of febrile patients in hospitals by efforts of the Reference Center, according to the results of which 60 % of all registered patients with WNF in Russia were diagnosed. Monitoring studies of the Reference Center in the territory of the Central, Southern and North-Caucasian Federal Districts confirmed the intensive circulation of the pathogen. The low level of officially registered incidence is caused by insufficiently effective identification of patients. Molecular genetic studies have shown that West Nile virus lineage 2 circulated in the European part of Russia, both in epizootic and epidemic cycles. Phylogenetic analysis has revealed that 4 West Nile virus isolates found in Astrakhan, Volgograd Regions, the Republic of Kalmykia and Stavropol Territory in 2022 belong to a new genovariant of the genotype 2, first identified in Russia in 2021. Possible complication of the epidemiological situation in all federal districts of the center and south of the European part of Russia is predicted.

85-95 2091
Abstract

The paper provides the analysis of epidemiological process of hemorrhagic fever with renal syndrome (HFRS) in the Russian Federation in the context of federal districts in 2022 and a forecast of the HFRS incidence for 2023. According to the results of the analysis, there was a three-fold increase in the morbidity rates of HFRS in Russia in 2022 as compared to the indicators of 2021. The evidence of epizootiological survey and laboratory studies in certain federal districts of the Russian Federation indicate the continuing tense epidemiological situation on HFRS. In a number of regions of the country, high risk of infection with HFRS is predicted due to the favorable natural and climatic conditions of the winter period 2022/2023 for reservoir hosts of pathogenic for humans Hantaviruses. The findings of infected rodents attest to a high probability of complication of the epidemiological situation in the territories of increased epidemic hazard as regards HFRS.

ORIGINAL ARTICLES

96-104 703
Abstract

The aim of the study was to develop methodological approaches to assessing the economic damage associated with the incidence of hemorrhagic fever with renal syndrome (HFRS) and to calculate the economic damage by the example of an outbreak of HFRS in the Saratov region in 2019. Materials and methods. The paper analyzes the economic indicators of the Federal State Statistics Service; data on the incidence of HFRS in the Russian Federation for the period of 2019–2022. To calculate the cost of outpatient and inpatient medical care, as well as the costs associated with the medical follow-up of convalescents, the indicators of the Program of state guarantees of free provision of medical care to citizens for 2022 and for the scheduled period of 2023 and 2024 were used. The calculation of economic losses associated with the payment of temporary disability benefits was carried out according to the equation provided in the Federal Law No. 255-FZ dated December 29, 2006 (as amended on October 07, 2022). Economic losses associated with premature death at an economically active age were calculated based on the value of unproduced GDP due to lost years of life in the corresponding age group. Results and discussion. The costs of treatment, rehabilitation and payment of temporary disability benefits for 1 case of HFRS at the age of 0 to 56.5 years for the female population and from 0 to 61.5 years for the male population amount to 140 495 rubles; over the age of 56.5 years for the female population and 61.5 years for the male population – 95 412 rubles, respectively. Each fatal case of HFRS aged 0 to 16 years among the male population costs the state 38 976 231 rubles; among the female population – 34 708 331 rubles; in active working age – the value of economic damage varies depending on the age of the person who died of HFRS. The economic damage of the outbreak of HFRS in the Saratov Region (2019), taking into account the direct expenditures of the healthcare system and indirect losses of the country’s economy amounted to 441 453 432 rubles. It is of note that the structure of the main damage is dominated by indirect losses in the economy caused by the premature death of people in economically active age.

105-110 965
Abstract

The aim of the work was to obtain and characterize hybridomas producing monoclonal antibodies to antigens of coronavirus SARS‑CoV‑2, promising for the construction of diagnostic immunochemical tests. Materials and methods. Recombinant nucleocapsid and receptor binding fragment of spike protein of SARS‑CoV‑2 were used for immunization of BALB/c mice. Antigens were absorbed on aluminium hydroxide gel and injected subcutaneously to BALB/c mice at a 7-day-interval. Immune splenocytes and myeloma cells SP2/0-Ag14 were fused by polyethylene glycol 1450. Cell cultures producing specific antibodies against nucleocapsid and receptor binding fragment were selected applying indirect ELISA in 96-well plates sensitized by desired antigens. Clones of hybridomas were obtained using the method of limiting dilutions. Production properties were studied through in vitro cultivation in 24-well culture plates. Immune-ascitic fluids were collected during the cultivation of hybrid cells in peritoneal cavities of BALB/c mice. Monoclonal antibodies were purified by affinity chromatography on protein A sepharose sorbent, conjugated with horseradish peroxidase, and tested for the possibility to be used in sandwich ELISA for detection of inactivated SARS‑CoV‑2 coronavirus strain “Isolate B”. Results and discussion. As a result of hybridization and selection of clones, hybridomas producing monoclonal antibodies to nucleocapsid and receptor binding fragment of SARS‑CoV‑2 have been obtained. During the in vitro and in vivo cultivation the clones maintained the consistent proliferative and antibody producing activity. The application of monoclonal antibody 415D12 as a capture one and 411D12 antibody conjugated with horseradish peroxidase as a detector antibody in ELISA allows for identifying SARS‑CoV‑2 coronavirus at a minimum concentration of 1·103 PFU per ml.

111-119 514
Abstract

The aim of the study was to analyze the genetic structure of populations and the patterns of evolutionary variability of the novel coronavirus infection in the Siberian and Far Eastern Federal Districts. Materials and methods. 1033 SARS-CoV-2 genomes from samples from individuals diagnosed with COVID-19 from eight entities of the Siberia and Far East between December 2020 and November 2021 were assessed. Sequencing was performed on the MinION Oxford Nanopore platform using the ARTIC v.3 protocol. The degree of SARS-CoV-2 genetic isolation was estimated applying the Fst criterion. Phylogenetic analysis was carried out using maximum likelihood method and Bayesian phylogenetic inference. A nonparametric Bayesian Skyline Plot (BSP) model was used to reconstruct population dynamics. Results and discussion. The original SARS-CoV-2 variant (B.1) was identified in 100 % of the cases at the initial stages. The Alpha variant was detected in March-June, 2021; Beta – in single samples in March-May, 2021. Delta was first identified in April, 2021. The maximum degree of SARS-CoV-2 genetic isolation (Fst=0.18) was established for the most remote territories (Altai Territory ↔ Republic of Buryatia and Altai Territory ↔ Irkutsk Region). A relatively free circulation of the virus was detected between Irkutsk Region, Republic of Buryatia and Krasnoyarsk Territory. According to the results of population genetic tests, a sharp increase in the effective virus population size was the determining mechanism of SARS-CoV-2 genetic diversity formation. Reconstruction of population dynamics in BEAST (BSP model) has revealed the consistency of trends in the genetic diversity of the virus and the number of active cases. Two subclusters have been identified in the Delta cluster, consisting predominantly of samples isolated in the Irkutsk Region and Krasnoyarsk Territory. Change in the dominant variant of SARS-CoV-2 has been traced in dynamics. Molecular-epidemiological data point to the multiple pathways of spatial expansion of different SARS-CoV-2 genotypes into the constituent entities with generation of individual monophyletic clusters and further intra- and extraterritorial spread of the decedents.

120-125 378
Abstract

In 2022, there was an increase in the incidence of tick-borne encephalitis (TBE) and ixodid tick-borne borreliosis (ITBB) in the subjects of the Russian Federation, federal districts and the country as a whole. At the same time, among people affected by ixodid ticks, the proportion of clinical forms of the diseases has increased. The aim of this study is to analyze the possible causes of the simultaneous increase in the incidence of vector-borne infections and the proportion of clinical forms among the people bitten by the ticks, using the materials on Krasnoyarsk Territory as an example. Materials and methods. We analyzed the incidence of TBE and ITBB among the people who have or haven’t had COVID‑19, the number of people affected by tick bites in 2021–2022 in Krasnoyarsk Territory. Statistical analysis is performed by standard methods of variational statistics using Excel. Results and discussion. It is shown that in the Krasnoyarsk Territory, with a decrease in the number of individuals affected by tick bites in 2022 as compared to 2021 (12216 and 13214, respectively), there was an increase in the number of cases of TBE (from 124 to 250) and ITBB (from 115 to 224), as well as the proportion of people who had clinical forms of the infections after tick bites. Among three possible explanations of the observed pattern, a decrease in the immune status of Krasnoyarsk residents who had had COVID‑19 before the contact with ticks is considered as the most likely one. Using statistical methods it was substantiated that among people with TBE and ITBB, the proportion of individuals who have had COVID‑19 is significantly higher than expected, based on the actual incidence of the Krasnoyarsk Territory population with a new coronavirus infection. Thus, COVID‑19 affects the incidence of vector-borne infections indirectly, through a change in the number of people contacts with natural stations, and directly, by changing the immune status.

126-131 440
Abstract

The paper describes a developed comprehensive system for molecular-genetic identification of Yersinia pestis strains according to their appurtenance to certain subspecies, biovars, phylo-geographic populations, using realtime PCR (RT-PCR), allele-specific RT-PCR, and multiplex PCR with hybridization fluorescent registration of results on a solid substrate. Application of this system makes it possible to establish the appurtenance of Y. pestis strains to the following phylogenetic branches: 0.ANT1, 0.ANT2, 0.ANT3, 0.ANT5, 3.ANT, 4.ANT of antique biovar of the main subspecies; 2.MED0, 2.MED1, 2.MED2, 2.MED3, 2.MED4 of medieval biovar of the main subspecies; 1.IN1, 1.IN2, 1.IN3 of intermedium biovar of the main subspecies; 1.ORI1, 1.ORI2, 1.ORI3 of oriental biovar of the main subspecies; 0.PE3 (angolica subspecies), 0.PE7 (tibetica subspecies) and 0.PE10 (qinghaica subspecies). The first stage of the studies within the frames of the developed system is indication of plague agent using registered diagnostic drugs. The second stage is the determination of belonging to individual subspecies through RT-PCR or by the method of multiplex PCR system with hybridization-fluorescent registration of results on a solid substrate, which also allows for establishing to which biovars of the main subspecies and the main phylogenetic lines of the ancient biovar the strains belong. The third stage is the identification of strain appurtenance to phylogenetic branches by the AS-RT-PCR method. The designed complex system for molecular-genetic identification of Y. pestis strains can be applied at the regional and federal levels of the laboratory network of the Russian Federation for diagnostics of infectious diseases. Its use will considerably facilitate and increase the efficiency of intraspecific differentiation of Y. pestis strains within the framework of the epidemiological investigation of outbreaks or importation of strains of plague pathogen into the territory of the Russian Federation or during the certification of strains in collection activities.

132-141 449
Abstract

The aim of the study was to develop a method for intraspecific differentiation of the tularemia microbe: subspecies tularensis (subpopulations AI and AII), holarctica (biovars japonica, EryS/R), mediasiatica, and novicida using multilocus real-time PCR. Materials and methods. We used 48 strains of F. tularensis of various subspecies, biovars, and subpopulations. Intraspecific appurtenance of the strains was carried out on the basis of the analysis of the RD-1 region variability applying PCR, the sdhA gene by Sanger fragment sequencing and by the disk diffusion method using disks with erythromycin. The selection of primers and probes was performed using the software available at www.genscript.com and GeneRunner 6.5.52. Sequence homology was assessed using the BLAST algorithm and the GenBank NCBI database. Results and discussion. New data on the structure and occurrence of the differentiation regions RD-8, RD-12, RD-28 of FTT1122c gene and its homologous sequences in strains of tularemia microbe of various subspecies have been obtained. Novel RDhm 346 bp in size, characteristic of strains of the subsp. mediasiatica, holarctica, which is deleted in subsp. tularensis and absent in subsp. novicida has been detected. Based on the detection of the FTT1670, FTT1122с, FTT1067, FTW_2084 loci, a multilocus real-time PCR has been developed – “F. tularensis 4c”, providing for identification of all subspecies of the tularemia microbe, separately for the biovar japonica of the Holarctic subspecies and subpopulations AI, AII of the subspecies tularensis. The PCR specificity was confirmed in the study of strains of tularemia microbe from the fund of the “State Collection of Pathogenic Bacteria” at the premises of the Russian Reserarch Anti-Plague Institute “Microbe”. The results obtained expand the concept of intraspecific genetic heterogeneity of tularemia microbe and possibilities of identifying the causative agent of tularemia using molecular-genetic methods. They are important for understanding the processes of adaptation of the pathogen to circulation in the host organism and environmental objects, the course of evolution and formation of new species of Francisella.

142-147 438
Abstract

The causative agent of Q fever, the intracellular pathogen Coxiella burnetii, is found almost worldwide; many types of blood-sucking ticks that are dangerous to animals and humans are involved in the circulation of the pathogen. Using molecular-genetic methods, closely related species of microorganisms of the genus Coxiella sp. have been discovered, some of which are endo-symbionts of ticks, and some can survive in the human body, causing an infectious process. The existence of species whose genes are similar in nucleotide sequence to those of C. burnetii makes it difficult to diagnose the pathogen in arthropod vectors. The aim of this work was to consider the use of PCR and sequencing of an extended 16S rRNA gene fragment for molecular diagnostics and differentiation of C. burnetii from Coxiella-like microorganisms. Materials and methods. Individual samples of blood-sucking ticks were examined to detect bacteria of the genus Coxiella sp. applying standard PCR. For positive samples, an extended fragment of the 16S rRNA gene was obtained and examined by sequencing and multiple alignment with homologous sequences. Results and discussion. Of the 96 examined ticks collected in the Ulyanovsk Region, one was positive for the presence of C. burnetii DNA and one – for the presence of Coxiella sp. The greatest similarity for the C. burnetii isolate was noted in comparison with Western European strains, for the Coxiella-like microorganism - with closely related bacteria from ticks of the same species. Unique polymorphisms for the detected microorganisms were identified. It has been established that genus-specific primers to the 16S rRNA gene fragment are able to amplify not only bacteria of the genus Coxiella sp., but also genetically distant species. Analysis of the sequence of the extended 16S rRNA gene fragment makes it possible to differentiate C. burnetii from Coxiella-like microorganisms; some gene polymorphisms appear to have arisen through microevolution in different geographic regions. In the European part of the Russian Federation, Coxiella-like bacteria have been uncovered for the first time.

148-156 560
Abstract

Consolidation of the efforts in implementation of epidemiological surveillance and control over plague and other dangerous natural-focal infections is an essential aspect in ensuring epidemiological well-being as regards particularly dangerous infectious diseases in the territory of natural plague foci and potentially focal territories located within the borders of the Russian Federation and the Republic of Kazakhstan. The aim of the work was to carry out a joint epizootiological survey of the transboundary territories of the Volga-Ural sandy natural plague focus and the territory of the East Kazakhstan region of the Republic of Kazakhstan (RK) potentially focal for plague over the period of 2019–2022. Materials and methods. Samples of field materials, collected during the epizootiological survey of the territory of Kazakhstan, were studied using bacteriological, molecular-genetic, and immune-serological methods. Results and discussion. We have obtained the current evidence on the spatial-biocenotic structure, the circulation of pathogens of dangerous natural-focal infectious diseases in the transboundary territories of Eastern and Western Kazakhstan. It has been established that the conditions that contribute to the possibility of human infection with plague and other dangerous infectious diseases in case of the aggravation of epizootic situation in the foci or importation of the pathogens into the territory are in place.

157-163 717
Abstract

The aim of this work was to develop an oral method of vaccination against anthrax, since wide vaccination campaigns using this method require no special conditions, equipment, and instruments. Also, minimum number of medical personnel is sufficient to ensure control over the intake of the drug. Materials and methods. Domestic raw materials, consumables and reagents that passed the incoming inspection and met the requirements of State and industry standards, technical specifications, and the articles of the Pharmacopoeia were used for the work. Batches of anthrax vaccines based on Bacillus anthracis strain STI-1, manufactured at the Research Center (Kirov) of the “48th Central Research Institute” of the Ministry of Defense of Russia were put to the test. Results and discussion. The immunization schemes have been tested on animals, taking into account the features of the antigen. One of the crucial factors that determine the effectiveness of oral vaccination is the correct choice of the type and form of the oral anthrax vaccine administered enterally. It has been shown that in contrast to oral vaccines, the vaccine strain in enteral vaccines must be protected from the harmful effects of stomach contents. Thus, enteric-coated capsules coated with a shell that is resistant to the action of stomach acid were used for the study. The presented experimental data indicate that a single administration of the capsules with oral anthrax vaccine STI protects at least 70 % of laboratory animals from a highly virulent strain of the anthrax microbe and confirm the safety and non-reactogenicity of the drug. The developed laboratory technology makes it possible to obtain a finished product containing one inoculation dose of an oral vaccine for laboratory animals. So, a new method of vaccination has been designed. It is necessary to conduct preclinical and clinical trials to promptly introduce the oral administration of anthrax vaccine into medical practice as the simplest method for mass vaccination of humans.

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ISSN 0370-1069 (Print)
ISSN 2658-719X (Online)