The Sari-Dzhas natural mountain focus of plague with an area of 5000 sq. km is located mainly in Kyrgyzstan. This enzootic area belongs to a group of Tien-Shan mountain plague foci and crosses the boundaries of Kazakhstan, Kyrgyzstan, and China. After collapse of Soviet Union, this area was not investigated fully, thence we have estimated current status of hosts and vectors comparing to 1977 in the Sari-Dzhas focus. For period 1977-2014, the number of the gray marmot (Marmota baibacina) as main host of plague has decreased twice due to regular chemical suppression of focal area, but now there is a tendency for population recovery. If negative impact of human activity (hunting, livestock, and tourism) will be minimized, the population density should rise in the near future, related to high reproduction score of animals. Significant increase of number of narrow-skulled vole (Microtus gregalis) observed on focus area in 1977-2017 can effort a risk of pathogen transmission in cross-populations of marmots provided by recovery of vector number between different hosts. For whole observation period in the Sari-Dzhas focus were described 33 species of marmot fleas with dominated Oropsylla silantiewi (67% from whole amount of fleas) and Radinopsilla li ventricosa (6.5%). Deep dustation of marmot burrows by 10% dichlorodiphenyltrichloroethane (DDT) conducted in 1980s caused significant decrease of ectoparasite abundance: the number of specific fleas is strongly diminished, while recovery of ticks and lice number is faster. At the same time, Yersinia pestis constantly circulates in the focal area, which is comfortable for interacting of human populations and pathogen hosts. Last plague epizootic was recorded in 1983 and recent outbreaks among gray marmot and its vectors with varying intensity are registered again starting from 2012. Thus, the Sari-Dzhas natural plague focus remains active with all links of plague epizootic cycle (marmot-vector-rodent) and needs strong monitoring every year.
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.
The main purpose of this study was to clarify the role of gray marmots ( Marmota baibacina ) in the long-term maintenance of highly virulent strains of Yersinia pestis in two plague endemic foci of the Tien Shan Mountains in Kyrgyzstan. We present data from regular observations of populations of M. baibacina and small rodents cohabiting with marmots in the mountainous grasslands of the Sari-Dzhas (east of Issyk-Kul Lake) and the Upper-Naryn (south of Issyk-Kul Lake) natural foci. During 2012–2017, an abundance of marmots and their ectoparasites (fleas and ticks) was significantly higher in Upper-Naryn comparing to Sari-Dzhas, although there were no differences in a number and diversity of small rodents cohabiting with marmots. The plague bacterium was detected either in marmots or in their ectoparasites collected during 4 of 6 years of observation in Sari-Dzhas and during 2 of 4 years of observation in Upper-Naryn. Plague was found in three sectors situated closely to each other in Sari-Dzhas and in 1 of 8 repeatedly surveyed sectors in Upper-Naryn. During 6 years, we isolated 9 strains of Y. pestis from marmots, two from their fleas Oropsylla silantiewi , one from an unidentified tick, and one from the gray hamster ( Cricetulus migratorius ). All plague strains isolated from the rodents and their ectoparasites in this study were similar to Antiqua biovar specific for marmots. The results indicate that plague can circulate continuously in the Tien Shan Mountains in populations of gray marmots and their ectoparasites with a facultative involvement of other rodent species after significant changes in rodent communities that happened in Kyrgyzstan during the previous two decades. The simultaneous field survey of two natural foci of plague, Sari-Dzhas, and Upper-Naryn, would be important for further analysis of circulation of Y. pestis strains belonging to Antiqua biovar in the Tien Shan Mountains.
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.
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