Aim. Analysis of epidemic manifestations of natural-foci infections (NFI), clarification of spectrum of their causative agents, determination of epizootic activity of natural foci in the Crimea Federal District (KFD). Materials and methods. Epizootologic examination of 10 administrative districts of KDF was carried out. 291 pools (2705 specimens) of ixodes ticks and 283 samples of organs of small mammals were studied by PCR method for the presence of DNA/RNA of causative agents of a number of NFI. Results. Morbidity by NFI in KFD was registered by 6 nosologies: Lyme borreliosis, Marseilles fever, leptospirosis, tularemia, intestine yersiniosis and tick-borne viral encephalitis, wherein, transmissive infections made up 91.6%. Circulation of causative agents of Crimea hemorrhagic fever, Q fever, group of tick-borne spotted fever, Lyme borreliosis, human granulocytic anaplasmosis, human monocytic ehrlichiosis, hemorrhagic fever with renal syndrome, West Nile fever, tularemia and leptospirosis was established. Conclusion. Due to activity of natural foci of NFI further monitoring of epidemiologic and epizootologic manifestations of these infections in the Crimea, including using genetic methods of analysis, is necessary for ensuring sanitary-epidemiologic welfare of KFD population.
Analysis of the long-term data made it possible to identify three periods of epizootic activity of the Central Caucasian high-mountain natural plague focus against the background of the overall downward trend. In the third period (2000-2010) the focus was shown to be under the intense negative influence of natural and anthropogenic factors that stipulated its depression. The natural factors were weather conditions unfavorable for life-sustaining activity of mountain ground-squirrels, the main plague carriers in this focus. Anthropogenic pressure over the focus manifested as follows. The quantity of cattle decreased, that resulted in decrease of territories of the mountain pasturelands, the natural habitats of mountain ground-squirrels. As areas suitable for life-sustaining activity of the mountain ground-squirrel populations reduced, the number of their settlements declined. With account taken for the effect of the anthropogenic influence stated above, short-term and medium-term prognoses of epizootic activity of Central Caucasian high-mountain natural plague focus indicate of rare non-intensive epizooties.
Aim. Determination of the degree of phylogenetic relationship of Yersinia pestis strains isolated from the territories of natural foci of plague from the Caucasus using VNTR-typing by 25 loci (MLVA25). Materials and methods. 26 strains of Y. pestis from Russian natural foci of the Caucasus were used in the study. 25 loci of tandem repeats in Y. pestis genome by Le Fleche scheme were used for execution of multi-locus VNTR-analysis. Deciphering of nucleotide sequences was carried out in automatic sequencer ABI 3130 Genetic Analyser. Analysis of confinement of clusters to certain territories, objects and time of isolation of strains was carried out using Arc GIS 10.1 program. Results. Groups of MLVA25-types of various levels of discrimination were formed: clusters, groups and subgroups. Clusters were formed by strains of various taxonomic membership: main and subspecies of Y. pestis. Subgroups reflect membership of strains in certain foci, and MLVA25-types - the degree of genetic relationship. Conclusion. Genetic «portraits» of plague causative agents obtained using MLVA25-types circulating in various natural-focal territories allow to solve problems ofboth theoretical and practical character: from interpretation of microevolution processes to the search of the source of infection and ways of its spread during possible epidemic complications.
Studied have been Yersinia pestis strains isolated in Central-Caucasian high-mountain natural plague focus within the period of 1971-2012 using MLVA typing on 25 VNTR-loci. Analysis of dendrogram cluster association with certain areas, objects, and periods of the strain isolation has been carried out by means of Arc GIS 10.1 software. Established has been the connection between 25 MLVA Y. pestis types and spatial and temporal characteristics of strains isolation in the Central-Caucasian high-mountain natural plague focus, and proline requirement too. Clusters, groups and subgroups of the strains are confined to particular territories as it follows: groups are attributed to landscape-epizootiological regions, subgroups-to mountain souslik settlements. Occasionally groups of the strains disseminate onto the other landscape-epizootiological regions of the focus. Genetic variations of plague agent strains within the limits of mountain souslik settlements evolve over time which can be viewed as indirect evidence of microevolution mechanism effect.
цель. предложить на основе вероятностного подхода научно обоснованный критерий исключения части очаговой территории из обследования и, соответственно, из состава очага. материалы и методы. данные по эпизоотологическому обследованию центрально-кавказского природного высокогорного очага чумы с 1987 по 2013 год (28 лет). для каждого сектора первичного района в очаге посчитана кратность обследования и кратность регистрации эпизоотий. для статистической обработки использовались непараметрические методы: коэффициент ранговой корреляции спирмена, квантильный анализ и некоторые понятия теории вероятности. результаты и обсуждение. на примере центрально-кавказского природного высокогорного очага чумы представлен метод расчета вероятности появлений эпизоотий в секторах очага. предложен математически обоснованный критерий исключения сектора из очаговой территории. представлен алгоритм исключения секторов первичных районов из плана обследования при разных уровнях значимости. ранжирование очага по вероятности выявления эпизоотии в секторе и вероятности обследования сектора может быть использовано, наряду с индексом эпизоотичности, при планировании эпизоотологического обследования очаговой территории. Ключевые слова: природный очаг чумы, эпизоотии, сектора первичных районов, кратность обследования, вероятность.
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