Search

The aim of the work was to study the genetic diversity and spatial-temporal genotype structure of Yersinia pestis subspecies central asiatica biovar altaica in the Gorno-Altai natural plague focus, using MLVA25-typing.Materials and methods. MLVA25-typing of 330 strains of Y. pestis ssp. central asiatica bv. altaica, isolated in the Gorno-Altai mountain natural plague focus during 1961–2015 was carried out. The phylogenetic tree was constructed with the help of UPGMA and MST algorithms.Results and discussion. The analyzed strains have been differentiated into 34 MLVA types based on cluster analysis. The formed major groups of strains show pronounced spatial confinedness. Three chorological groupings of the plague agent with peculiar genotype characteristics have been identified. Each of the groupings is circulating among the main carrier (Ochotona pallasi) population and within the limits of the similarly-named mesofocus, respectively (Ulandryksky, Tarkhatynsky and Kuraisky). MLVA25 structure of Y. pestis in Ulandryksky and Kuraisky mezofoci show stability over time; there are no significant changes from the time of their first detection in 1961 and 1999, respectively. The dramatic changes in MLVA25 structure are observed in Tarkhatynsky mesofocus, which is known from 1972. Mass expanding of the MLVA25 types which were very rare before took place there from the beginning of 1990-s, along with elimination of the types absolutely dominant up to 1980s. Most likely the changing of dominating genotypes is attributable to the bottleneck effect, arising from the sharp decline of the focal epizootic activity in the mid 1980s.

The aim of the study was molecular-genetic identification and analysis of the phylogenetic relationship of Yersinia pestis strains isolated on the Ukok Plateau in 2020, in order to establish the current boundaries of the natural mega focus of plague in the Altai Mountains in Russia and Mongolia.Materials and methods. 37 strains of Y. pestis of the main subspecies isolated in the Tuva mountain and Gorno-Altai high-mountain plague foci and adjacent territories of Mongolia in 1971–2020 were studied. The whole genome sequencing of the strains was performed using the Ion S5 XL System (Thermo Fischer Scientific). Ion Torrent Suite software package 5.12 and Newbler gsAssembler 2.6 were used to process the data and assemble de novo the sequences of raw reads. The average size of the collected genome was 4.55 million base pairs. Core SNPs were detected by aligning the contigs of Y. pestis strains on the CO92 genome using the Snippy 4.6 program, then 28 SNP homoplasies were removed. The resulting set of SNPs contained only the core region of the genome (955 SNPs). The dendrogram was constructed using the Maximum Likelihood method applying the PhyML 3.1 program.Results and discussion. The current population structure of Y. pestis of the main subspecies, antique biovar, phylogenetic line 4.ANT, endemic to the foci of the Altai Mountains in Russia and Mongolia has been determined. The presence of 4.ANT-21 clone, which became widespread in the territory of these natural foci of plague at the begining of the XXI century, was revealed. It is shown that three strains isolated on the Ukok Plateau in 2020 belong to clone 4.ANT-21. According to phylogenetic analysis, evidence of 4.ANT circulation on the Ukok Plateau before 2018 was obtained. The lesson that has been learned is that it is necessary to study the territories of Mongolia, Kazakhstan and China bordering the Ukok Plateau in order to establish the current boundaries of the 4.ANT mega focus.

Objectiveof the study was monitoring of epizootic situation in the Mongolian part of the trans-boundary Sailugem natural plague focus through 2018 for optimization of preventive and anti-epidemic activities to decrease the level of risk of human plague cases among the population in the border areas of Mongolia and Russia.Materials and methods. Epizootic survey was conducted across the area of 2668 km2 ; 282 mammals, 261 ectoparasites, including 257 fleas, were tested for plague. All laboratory investigations of the field material were carried out in the mobile laboratory for monitoring and diagnostics, mounted on the platform of KAMAZ. Field samples were subjected to molecular-genetic (PCR) and serological tests. Fresh and mummified pickings of birds of prey, corpses, caught rodents and lagomorphs, fleas collected from corpses, were tested using immune-chromatographic method (ICM) to detect capsular antigen (F1) of plague microbe. PCR and ICM positive samples were investigated applying bacteriological method. In the course of epizootiological survey, GIS-tools were employed. All the results obtained were plotted on electronic maps using QGIS 2.12.3 software package.Results and discussion. The total of 47 Yersinia pestis ssp. pestis strains were isolated from grey marmots and their fleas. Y. pestis DNA was detected in 60 objects. Serological testing showed 60 positive results. Contamination of the caught souslik with plague agent reached 4.5 % (n=22), fresh corpses and picking of predatory birds – 63.4 % (n=41), mummified corpses and leftovers, skeletal remains – 10.0 % (n=140). It was established that in the border territory, adjacent to Russia, an intensive diffused plague epizooty, caused by the agent of the main subspecies, takes place. All epizootic manifestations were revealed at the altitudes of 2400–2800 m above sea level, in densely populated grey marmot settlements. The epizooty was registered in most of the southern macro-slope of Sailugem ridge, throughout 100 km and along the whole Karalakhtu ridge – throughout 30 km. The epizooty area, confirmed by plague agent isolation, amounted to 1207 km2 (45.2 % of the examined territory).

Objective – to study the current epidemiological risks at plague enzootic frontier territory of the Bayan-Ulgy aimag of Mongolia. Materials and methods. Epidemiological analysis was performed according to the reporting documentation of the National Centre of Zoonotic Infections in Mongolia, results of anonymous questioning of 179 residents of the Bayan-Ulgy aimag of Mongolia, materials of the Department of Health of the Bayan-Ulgy aimag, the Aimag Centre of Zoonotic Infections and the Administration of the Aimag Governor. Results and discussion. Plague was first registered in the Bayan-Ulgy aimag in 1989. The total of 9 patients with plague and 4 lethal outcomes were revealed. In all cases marmots were an infection source, the infection occurred in the process of cutting the carcasses. The majority of the plague patients had bubonic form of plague. All patients were men aged 13 to 34 years. Public inquiry showed that 21,8 % of population considered meat of marmots as a delicacy, 54 % – hunted for the animals, 25,7 % – consumed uncooked organs of marmots as a folk remedy, 19,5 % – participated in cutting of marmot carcasses. Results of the inquiry indicated that a marmot was an object of active hunting for local population. Analysis of epizootic activity of the transboundary Sailugem natural plague focus, modern social and economic conditions in the Bayan-Ulgy aimag has showed that in this territory epidemic risks have shaped and act at present. They can be divided into two groups: epidemic risks capable to cause human sporadic plague cases and epidemic risks leading to anthropozoonotic plague dissemination among the population and exportation of Yersinia pestis beyond the limits of enzootic territories. Effective interaction of anti-epidemic Institutions of Mongolia and Russia and also the Agencies and Institutions of the executive power of all levels permits to counteract these risks.

Objective of the study is to comprehensively evaluate and forecast the development of epidemic process in case of anthrax in Altai Territory. Materials and methods. The data on stationary hazardous as regards anthrax areas (SHA) were obtained while analyzing cadastres of SHA in Altai Territory, as well as the reference book “Cadastre of stationary hazardous as regards anthrax areas in the Russian Federation”. Statistical and report forms from the institutions of the Rospotrebnadzor and Federal Service for Veterinary and Phytosanitary Surveillance in Altai Territory, and from Altai Plague Control Station were used for retrospective analysis of anthrax morbidity rates in Altai Territory over the period of 1953–2015. Laboratory investigations of field and clinical samples were carried out in compliance with Methodological Regulations 4.2.2413-08. Results and conclusions. Anthrax remains topical issue for Altai Territory as there are 1262 stationary hazardous areas situated in here, as well as registered animal and human infections. The density of such areas in Altai Territory is 7.5 times higher than across Siberia. Factors for the SHA formation and their sustainability are soilclimatic aspects of the region. The majority of hazardous areas are found in steppe and forest-steppe zones, predominantly along the cattle-driving paths. In Altai Territory, between 1953 and 2015, out of 1262 registered areas, 314 ones manifested epidemiological activity, including 246 new ones. Human infections were reported in 36 districts (59.1 %), while in 21 (34.4 %) – morbidity rates exceeded the territorial average. Cumulative dynamics of anthrax morbidity as regards livestock in Altai Territory in 1953–2015 showed downward trends. Complex evaluation of the situation and forecast of epidemic process development, employing composite index – epizootiological index and zoning of the territory according to the risk of epidemic complications – allows for the improvement of managerial decisions with the view to adequate anti-epidemic measures.

Objective of the study is to characterize the case of human plague in the territory of Gorno-Altaisk high-mountain natural focus in 2015 and to analyze the initiated measures, associated with localization and elimination of epidemic focus. Materials and methods. Utilized are the data contained in reporting and source (primary) documentation of the FGHI “Altai Plague Control Station”, records of the Rospotrebnadzor Administration in the Republic of Altai, and information collected by the FGHI “Irkutsk Research Anti-Plague Institute”. Results and conclusions. Human infection occurred as a result of gray marmot dressing, which was caught in the Elangash River-Valley, against the background of unfavorable epizootic situation, caused by proliferation of the plague agent of main subspecie in the territory of the focus. Clinical material investigations, performed by means of bacteriological and molecular-genetic methods, showed negative findings. Applying serological method within the system of indirect hemagglutination test (IHAT)/antigen neutralization test (ANT), in blood sera, obtained at the time of hospitalization, low-titred specific antibodies to plague microbe (recognized as post-vaccinal ones) were detected. In blood serum sample, obtained 7 days later, identified were high-titer antibodies, which allowed for confirmation of clinical diagnosis - “bubonic plague”. Due to efficient cooperation between Rospotrebnadzor institutions and medical facilities, as well as municipal authorities it was possible to avoid further development of anthropogenic transmission of plague; to localize and eliminate epidemic outbreak of this dangerous infectious disease in Kosh-Agach Region of the Republic of Altai in the shortest possible time.

Objective of the study was a complex pheno- and genotypic investigation of Yersinia pestis I-3595 and Y. pestis I-3596 strains, isolated from marmots that were the source of human infection in 2015. Materials and methods. A comprehensive microbiological, molecular-genetic and mass-spectrometric studying of Y. pestis ssp. pestis strains, isolated from two grey marmots that became a cause of the plague case in Gorno-Altai high-mountain focus in 2015, was performed using up-to-date methods. Results and conclusions. It was established that the studied Y. pestis strains belonged to the main subspecies. Results of plasmid screening, multilocus VNTR-and mass-spectrometric analyses showed that those strains were closely related to Y. pestis variant detected in the focus in 2012 and in 2014, and circulating in Northwest Mongolia and Tuva natural focus.

Objective of the study is to substantiate performance, assess the conditions, and analyze the results of activities on non-specific plague prophylaxis in the epizootic territory. Materials and methods. Utilized were archival data and operational reports of Altai Plague Control Station, Irkutsk RAPI, RusRAPI “Microbe”, Center of Hygiene and Epidemiology in the Republic of Altai, and Rospotrebnadzor Administration in the Republic of Altai, as well as literature sources. Spatial analysis was carried out using GIS-technologies. Results and conclusions. Concerted and coordinated activities of the Rospotrebnadzor institutions, medical and veterinary institutions, local executive authorities have allowed for complex prophylactic and anti-epidemic measures on prevention of plague dissemination and transmission in the territory of the Republic of Altai in 2016. Demonstrated has been the necessity to expand the scope and scale of operations and scientific research in the focus, deploying advanced toolkit of methods and means.

Objective of the study is to sum-up the results of prophylactic (anti-epidemic) measures associated with elimination of epidemic focus in Kosh-Agach Region of the Republic of Altai in 2016. Materials and methods. Utilized were the data of reporting and source documentation from Altai Plague Control Station, Rospotrebnadzor Administration in the Republic of Altai, RusRAPI “Microbe”, and Irkutsk RAPI. Results and conclusions. It is pointed out that carried out in 2016 complex of organizational, anti-epidemic, and sanitary-prophylactic activities against plague is the importnant stage of rehabilitation of Gorno-Altai high-mountain natural plague focus, the final goal of which is maximally possible decrement of risks of primary human infection with plague, and in case of occurrence of such – performing of prompt response measures on localization and elimination of epidemic focus. It has been substantiated that for epidemic risk minimization in 2017 it is necessary to continue prophylactic vaccination, desinsection and deratization in the areas of predictive epizootic situation aggravation, which is contained in “Complex Action Plan of the Rospotrebnadzor Institutions for Sanitation and Rehabilitation of Gorno-Altai high-mountain natural plague focus in Kosh-Agach Region of the Altai Republic in 2017”. It is also necessary to provide for implementation of the Program on lowering risks of importation from cross-border Sailyugemsky natural focus and spread of plague in the territory of the Russian Federation, within the frames of RF Government Order No 1864-p, dated 05.09.2016.

Laboratory diagnostics of plague was carried out in compliance with valid operational guidelines and regulations. But its peculiarity consisted in the performance of diagnostic investigations secondary to antimicrobial therapy with application of preparations characterized by the expressed activity towards gram-negative microorganisms, including the agent of plague (ceftriaxone, ciprolet, and amikacin). The studies revealed that under antibiotic treatment during the early phase of infection the most effective method for the laboratory plague diagnostics was PCR. Based on the results of the assay it was possible to establish not only provisional, but also the final diagnosis in a patient. Obtained was genetic characteristics of the strains isolated from the patient and the marmot, withdrawn at the patient’s place, using techniques of molecular-genetic analysis, in particular PCR, multilocus VNTR, and multilocus and genome-wide sequencing. Thereupon the strains were attributed to antique biovar of the main subspecies of plague agent. In addition, close relation to Y. pestis of the main subspecies isolated in the same focus in 2012 and to the strains from Mongolian Altai and Tuvinian mountain focus was determined based on phylogenetic analysis of the isolates.

Performed is a complex microbiological, molecular-genetic and mass-spectrometric identification of Yersinia pestis main ssp. strain, which was isolated for the first time in the history of surveillance over the Altai mountain natural plague focus in June, 2012. Determined is its high universal virulence. Plasmid screening, multi-locus VNTR- and mass-spectrometric analyses have revealed the strain to be more closely related to the plague agent variant, circulating in the territory of the natural focus Khuukh-Serkh-Munkh-Khairkhan, Bayan-Ul’giisk aimak, Mongolia.