The aim of the study was to clarify the boundaries of the Central Asian natural plague focus of Kazakhstan and the modern boundaries of the areal of the great gerbil (Rhombomys opimus) in order to improve epizootiological monitoring and increase the effectiveness of preventive (anti-epidemic) measures.Materials and methods. Data from the epizootiological monitoring of the great gerbil populations in 14 autonomous foci of the Central Asian desert natural plague focus in the Republic of Kazakhstan between 2010 and 2020 were used for the analysis. An epizootiologic survey of an area of 875350 km2 was carried out. When processing the data, epidemiological, epizootiological, statistical research methods, as well as GIS technologies were used.Results and discussion. An increase in the total area of the Central Asian desert natural plague focus of the Republic of Kazakhstan by 79710 km2 (9.98 %) has been established for the period of 1990–2020. It is noted that the change in the area of plague-enzootic territory was a consequence of the ever changing areal of the main carrier of plague pathogen – the great gerbil – under the influence of climatic and anthropogenic factors. The most significant changes were found in the southeastern part of the plague-enzootic territory, including those for the Betpakdala (50 %), Balkhash (34.3 %), Taukum (13.3 %) and Mojynkum (0.32 %) autonomous foci. The area of the Aryskum-Dariyalyktakyr autonomous focus decreased by 2100 km2 (4 %). In 2000–2002, new Alakol’sky and Ili intermountain autonomous foci with a total area of 26759 km2 were discovered. It is shown that due to the regression of the Aral Sea, the areal of the great girbil expanded and the area of the North Aral and Kyzylkum natural plague foci increased by 10500 km2 (29.2 %) and 560 km2 (0.4%), respectively. The areas of the Aral-Karakum and UralEmba desert autonomous foci, on the contrary, decreased by 2000 km2 (2.6 %) and 12300 km2 (17.6 %), respectively. Passportization and landscape-epizootiologic zoning of the territory of the Central Asian desert natural plague focus of the Republic of Kazakhstan has been completed.
Since 2010, an active course of epizootics with the release of the plague pathogen, isolated from hosts and vectors has been established in 8 autonomous foci of the plague from 14 autonomous foci of the Central Asian plague focus in Kazakhstan. It was necessary to take into account the parameters of variability of the main component of the parasitic system – the plague microbe in the process of certification of landscape and epizootological zoning of natural foci of plague in Kazakhstan. The aim of the work was to study the phenotypic and genetic properties of strains of the plague microbe isolated in natural sandy plague foci of Kazakhstan. Materials and methods. The work used 1196 strains of Yersinia pestis isolated over the past 10 years (2010–2019) from natural sandy plague foci, strain passports, literature sources, data on certification of plague foci in Kazakhstan. The study of the strains was carried out by bacteriological, serological and molecular genetic methods. Results. Certification and typification of the territories of sandy plague foci were carried out, taking into account the phenotypic and molecular-genetic properties of Y. pestis strains isolated from 12 autonomous foci of the Central Asian plague focus of Kazakhstan in 2010–2019. According to the results of the study, 84 atypical strains were identified. As a result of the analysis, 18 genotypes were identified among the studied strains, of which 13 (72.2%) were unique and did not repeat in the sample. The remaining 5 genotypes formed 5 clusters, combining 20 strains (60.6%) and all strains were phylogenetically assigned to representatives of the Mediaevalis biovar. Key words: plague microbe, plague foci, phenotypic features, molecular genetic features
The aim of the study was to improve epizootiological monitoring and increase the effectiveness of preventive (anti-epidemic) measures for camel plague control in Kazakhstan.Materials and methods. We used the data on epizootiological and epidemiological monitoring in natural plague foci of Kazakhstan, long-term measurements and indicators for the period of 2000–2020 of the anti-plague and veterinary services of the Republic for the analysis. To process the evidence, epidemiological, epizootiological, microbiological, and statistical research methods, as well as GIS technology were applied.Results and discussion. The number of camels has increased by 2.2 times in Kazakhstan over the past 20 years. Where there were 98.2 thousand heads in 2000, it amounted to 216.4 thousand heads in 2020. Over the past 10 years, 152 camels died of unknown causes in the focal area of the country, but laboratory tests for plague turned out negative. According to the hazard criteria, the territory of the country has been conditionally divided into three zones: five regions with a high degree of hazard with a total area of 953.15 sq. km, five regions with medium degree of hazard with a total area of 1230.72 sq. km, and with a low degree of hazard – four regions and three cities of republican significance with a total area of 541.1 sq. km. Constant epizootiological monitoring over plague in camels is a necessity for the system of preventive measures.
In the Central Asia desert natural focus of plague, the major carrier of the Yersinia pestis agent is the great gerbil Rhombomys opimus, and its vectors include fleas of the Xenopsylla genus. Phenotypical and genotypical properties of the R. opimus populations, Xenopsylla fleas and Yersinia pestis strains have been studied in the Central Asia desert natural focus of plague. Phenotypic distinctions and population discreteness have been identified in R. opimus on the cytochrome b gene of the mitochondrial genome from three autonomous plague foci: Pre-Balkhash, Betpakdala and Pre-Ustyurt. Phenotypic distinctions have been found in Xenopsylla fleas in the Central Asia desert natural focus of plague, and the genotype of X. gerbilli minax fleas on the Cox2 gene of the mitochondrial DNA; these had been captured in the Betpakdala autonomous focus. The repertoire diversity in phenotypical properties of Y. pestis strains from different natural foci of plague has been demonstrated, and population discreteness of Y. pestis strains has been determined using the next-generation sequencing method for single nucleotide polymorphism genes. Results of the study suggest that geographical and environmental isolation and natural selection have led to heterogeneity in the three populations of the great gerbil, vector fleas and Y. pestis.
Revealed by morphological characters, physiological status, and genetic diversity of populations of the main plague host Rhombomys opimus Licht., 1823 in Central Asia desert natural focus is described.Differences in the skull parameters of R. opimus from different populations were revealed. It’s shown that gerbils from Moyunkum are separate autonomous populations group. Samples from Moyunkum and Mangyshlak differed from other samples. In Balkhash-Alakol depression found two regional complexes: Pre-Balkhash and Dzungarian.Study results of free amino acids level in R. opimus blood serum obtained by gas-liquid chromatography of blood sera from animals captured in different zones of Central Asian focus gave statistically significant differences. To determine genetic variability in ecological and geographical isolation of R. opimus populations the DNA was genotyped.DNA samples analysis combined the studied gerbil from the desert focus into four clusters with eighteen haplotypes. R. opimus sequence analysis taking into account data from territories of Iran, Kazakhstan and China, clustered into three large clusters. First cluster combined the sequences of Kazakhstan and China samples, while great gerbil captured in Kazakhstan is located in a separate treasure. Second and third clusters include sequences of a great gerbil captured in Iran.
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