We modeled the ecological niche of a globally successful Bacillus anthracis sublineage in the United States, Italy and Kazakhstan to better understand the geographic distribution of anthrax and potential associations between regional populations and ecology. Country-specific ecological-niche models were developed and reciprocally transferred to the other countries to determine if pathogen presence could be accurately predicted on novel landscapes. Native models accurately predicted endemic areas within each country, but transferred models failed to predict known occurrences in the outside countries. While the effects of variable selection and limitations of the genetic data should be considered, results suggest differing ecological associations for the B. anthracis populations within each country and may reflect niche specialization within the sublineage. Our findings provide guidance for developing accurate ecological niche models for this pathogen; models should be developed regionally, on the native landscape, and with consideration to population genetics. Further genomic analysis will improve our understanding of the genetic-ecological dynamics of B. anthracis across these countries and may lead to more refined predictive models for surveillance and proactive vaccination programs. Further studies should evaluate the impact of variable selection of native and transferred models.
Abstract. We compared a local clustering and a cluster morphology statistic using anthrax outbreaks in large (cattle) and small (sheep and goats) domestic ruminants across Kazakhstan. The Getis-Ord (G i *) statistic and a multidirectional optimal ecotope algorithm (AMOEBA) were compared using 1 st , 2 nd and 3 rd order Rook contiguity matrices. Multivariate statistical tests were used to evaluate the environmental signatures between clusters and non-clusters from the AMOEBA and G i * tests. A logistic regression was used to define a risk surface for anthrax outbreaks and to compare agreement between clustering methodologies. Tests revealed differences in the spatial distribution of clusters as well as the total number of clusters in large ruminants for AMOEBA (n = 149) and for small ruminants (n = 9). In contrast, G i * revealed fewer large ruminant clusters (n = 122) and more small ruminant clusters (n = 61). Significant environmental differences were found between groups using the Kruskall-Wallis and MannWhitney U tests. Logistic regression was used to model the presence/absence of anthrax outbreaks and define a risk surface for large ruminants to compare with cluster analyses. The model predicted 32.2% of the landscape as high risk. Approximately 75% of AMOEBA clusters corresponded to predicted high risk, compared with ~64% of G i * clusters. In general, AMOEBA predicted more irregularly shaped clusters of outbreaks in both livestock groups, while G i * tended to predict larger, circular clusters. Here we provide an evaluation of both tests and a discussion of the use of each to detect environmental conditions associated with anthrax outbreak clusters in domestic livestock. These findings illustrate important differences in spatial statistical methods for defining local clusters and highlight the importance of selecting appropriate levels of data aggregation.
Background. Epidemiological and epizootological monitoring of natural plague foci requires an integrated approach to solving problems, taking into account the phenotypic and genetic variability of Y. pestis and zoning of natural plague foci. The introduction of a new molecular genetic methodology aimed at studying the genomic polymorphism of the plague pathogen provides reliable results for the differentiation of not only groups, but also individual strains.The aim. To determine the genotypes of the plague microbe from different autonomous foci of the Republic of Kazakhstan.Materials and methods. 105 strains of Y. pestis isolated from various natural plague foci of Kazakhstan in 1951–2015 were studied. The phenotypic properties of the strains were studied using standard microbiological methods. A polymerase chain reaction (PCR) was used to detect fragments of the cafl, pst and YPO2088 genes. Multilocus variable number tandem repeat (VNTR) analysis (MLVA) was performed for 25 VNTR loci.Results. The phenotypic properties of the strains were preliminarily studied and the strains of the plague microbe were tested for specificity using the Pest-Quest test system (Kazakhstan). The PCR study confirmed the species-specific affiliation of Y. pestis strains. A variety of strains with typical phenotypic characteristics was revealed. MLVA for 25 key loci (MLVA25) revealed that the studied strains of the plague microbe are phylogenetically closest to the Mediaevalis biovar representatives. A phylogenetic tree of the studied strains has been obtained. It was found that 9 genotypes circulate on the territory of Kazakhstan, and their distribution in certain natural plague foci was determined.Conclusions. The resulting clustering indicates the relationship between the strain groups obtained on the dendrogram by the MLVA25 method and the territories of certain natural plague foci.
In the structure of the economy of the Republic of Kazakhstan (RK) according to the latest statistics, the growth rate of industrial development is noted. Growth of industrial production in the regional context was provided in 14 regions out of 16. The mining sector provides more than 2.9% of employment and 18% of gross value added in the economy. The development of industry of Kazakhstan requires the development of new territories, which is often difficult due to the presence of soil-dwelling of anthrax (anthrax animal burial sites). The territory of Kazakhstan is unfavorable for anthrax. Complete elimination of the infection is not possible due to the existence of soil-dwelling of anthrax. The article is devoted to assessing the risk of infection of people and animals on the territory of the soil-dwelling of anthrax and the possibility of reducing the sanitary protection zone (SPZ) in connection with the development of industrial enterprises. Aim. Laboratory-diagnostic analyses of samples of soil, groundwater, risk assessment of infection of people and animals on-site soil-dwelling of anthrax for the scientific substantiation of safe reduction of the SPZ soil-dwelling of the anthrax, which is located at an industrial facility. Methods. Samples and groundwater collection was carried out in accordance with the guidelines. The properties of the strains isolated from the samples were studied in accordance with generally accepted methods. To achieve this aim, the following methods were used to study samples for the presence of the causative agent of anthrax: bacteriological, biological, serological (fluorescence immunoassay, indirect hemagglutination test), genetic (PCR). The risk of infection was assessed on the territory of the soil dwelling (Aktobe region, Khromtau district, Khromtau) of anthrax using data on the epizootic and epidemic situation of anthrax. Results and discussions. Comprehensive studies of soil, surface and groundwater have been carried out. In bacteriological studies of soil samples in crops on the Hottinger's agar, single large, flat, matte-gray rough colonies with uneven edges and fringed processes were found. It was determined that all allocated isolates are typical soil microorganisms of Bacillus cereus involved in soil mineralization. There is no anthrax agent in the samples. We have assessed the risk of infection of people and animals in the territory of the soil dwelling of anthrax. It was determined that there is a low risk of infection of susceptible animals and people with anthrax on the territory of a soil-dwelling located in the Khromtau district, Aktobe region on the territory of an industrial facility. Conclusions. To solve the problem of safe reduction of the SPZ of the soil-dwelling of anthrax in order to expand the activities of an industrial enterprise, it is recommended to conduct a systematic microbiological monitoring of the soil center territory for three years by taking at least 200 soil, groundwater and groundwater samples, followed by an investigation of the presence of the bacillus anthracis and risk assessment of infection of humans and animals with the causative agent of infection. Keywords: anthrax, soil-dwelling, risk of infection, sanitary protection zone.
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