Objective of 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).
носителями чумы в природе являются свыше 233 видов млекопитающих, а переносчиками -162 вида блох [3,5]. активность эпизоотического процесса в природных очагах чумы, наряду с другими цель исследования -изучение энтомопаразитических нематод из блох грызунов, собранных в горноалтайском высокогорном природном очаге чумы в 2016-2017 гг., с определением их систематической принадлежности. материалы и методы. представлены результаты морфологического и генетического анализа энтомопаразитических нематод-паразитов блох Amphipsylla primaris primaris плоскочерепных полевок Alticola strelzovi, блох Rhadinopsylla li transbaicalica даурской пищухи Ochotona dauurica, блох Rhadinopsylla dahurica, собранных с входов в норы грызунов. результаты и выводы. определены нуклеотидные последовательности спейсерной области ITS2 рибоcомного оперона энтомопаразитических нематод трех видов блох: Amphipsylla primaris primaris, Rhadinopsylla li transbaicalica, R. dahurica. на основе сравнительного филогенетического анализа и выявленного высокого процента гомологии нуклеотидных последовательностей ITS2 области рибосомного оперона (92-99 %) установлена их принадлежность к видам Rubzovinema spp. и близкое родство с ранее предложенным нами полигостальным видом Rubzovinema polyxenica из блох C. tesquorum, А. rossica и C. secundus из волго-уральского степного очага чумы. впервые выявлена отдельная ветвь эволюции энтомопаразитических нематод -паразитов блох, представленная Rubzovinema spp. установлено широкое распространение нематод Rubzovinema spp. в биоценозах степной зоны россии в прикаспии и горном алтае.Ключевые слова: энтомопаразитические нематоды блох грызунов, систематическая принадлежность, очаги чумы.
Entomoparasitic nematodes are supposed to be a link between parts of Yersinia pestis population in the environment and the flea vector. The aim of the study was to assess the prevalence and intensity of infestation in the fleas of the long-tailed souslik with entomoparasitic nematodes on the territory of Mongun-Taiginsky station in the Tuva natural plague focus. Materials and methods. Fleas were collected during the scheduled epizootiological surveys in 2019–2021. In the course of taxonomic identification the presence of parasitic nematodes was registered. In order to evaluate the intensity of nematode invasion, a total of 190 fleas were dissected. The number of adult parasitizing females and presence of larvae was recorded. Statistical processing of the data was performed with the help of conventional methods using the Excel software. The criterion χ2 was applied; the influence of various factors (species, gender of fleas) on the studied parameters was assessed through single- and two-factor analysis of variance. Results and discussion. During three years of observations, entomoparasitic nematodes were found in six species of fleas: Citellophilus tesquorum, Frontopsylla elatoides, Rhadinopsylla li transbaikalica, Frontopsylla hetera, Oropsylla alaskensis, and Neopsylla mana. The differences in infestation with nematodes between the species are presented. The highest invasion rate – 25.1–25.6 % – is observed in Rh. li transbaikalica. The gender of leas does not influence their infestation. It is established that invaded fleas are more often found in the nest than in the fur of animals, they are less actively migrate to the burrow entrance compared to not invaded ones. Evaluation of infestation prevalence has revealed that fleas Rh. li transbaikalica are the hosts for nematodes of mono- or oligoxenic species, which do not occur in other fleas.
The review presents data on the antigenic structure and the current classification of epidemically significant serovariants of Listeria. Description of species-specific properties of serovariants of Listeria, which may be common for two or more species, and common antigens with staphylococci and typhoid and paratyphoid bacteria, are given. It has been shown that only the antigenic scheme of Listeria monocytogenes is of practical interest for medical microbiology. Importance of serotyping in the epidemiological analysis to determine the source of infections and ways of its spreading has been determined. Differences in the designation of serovariants in the diagnosis of listeriosis in medical practice are observed. High level of adaptive properties of Listeria, its ability to reproduce in an abiotic environment, including food, susceptibility of immunodeficient individuals, prevalence of food pathway of infection pose a significant danger of increased sickness rate with listeriosis. Serological diagnostics of Listeria has not been developed in detail, and the existing serological methods are aimed at identifying specific antibodies to listeria. Advantages of the serological method include: quick results and the possibility to study any biological material. Currently available serological methods have a number of disadvantages: low reliability of results and low specificity of the study. The most promising method for identification of a serological group of cultures, according to the world classification, is the multiplex PCR method, based on the correlation between the serogroup of an isolate and the presence of specific open reading frames in its genome.
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