Identifying hotspots of human anthrax transmission using three local clustering techniques

Barro, Alassane S.; Kracalik, Ian; Malania, Lile; Tsertsvadze, Nikoloz; Manvelyan, Julietta; Imnadze, Paata; Blackburn, Jason K.

doi:10.1016/j.apgeog.2015.02.014

Cited by 31 publications

(27 citation statements)

References 44 publications

(61 reference statements)

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“…In reality, TB outbreaks tend to disperse in space as they progress, thus a conical rather than a cylindrical window would be more appropriate to simulate this natural TB outbreak progression. SaTScan, nevertheless, has been shown to be very sensitive to low disease incidence, as is the case in this study and tend to overestimate rather than underestimate cluster sizes, as compared to other spatial cluster detection methods [ 61 ]. Finally, as the multinomial space-time models were not adjusted for foreign-born population density or county-level HIV risk, we cannot refute the alternative explanation that the Haarlem clades are widespread throughout North America and the Caribbean and that cluster membership reflects the spatial distribution of the US and Foreign-born populations in Florida.…”

Section: Discussionmentioning

confidence: 92%

Spatiotemporal Clustering of Mycobacterium tuberculosis Complex Genotypes in Florida: Genetic Diversity Segregated by Country of Birth

et al. 2016

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BackgroundTuberculosis (TB) is caused by members of the Mycobacterium tuberculosis complex (MTBC). Although the MTBC is highly clonal, between-strain genetic diversity has been observed. In low TB incidence settings, immigration may facilitate the importation of MTBC strains with a potential to complicate TB control efforts.MethodsWe investigated the genetic diversity and spatiotemporal clustering of 2,510 MTBC strains isolated in Florida, United States, between 2009 and 2013 and genotyped using spoligotyping and 24-locus MIRU-VNTR. We mapped the genetic diversity to the centroid of patient residential zip codes using a geographic information system (GIS). We assessed transmission dynamics and the influence of immigration on genotype clustering using space-time permutation models adjusted for foreign-born population density and county-level HIV risk and multinomial models stratified by country of birth and timing of immigration in SaTScan.Principal FindingsAmong the 2,510 strains, 1,245 were reported among foreign-born persons; including 408 recent immigrants (<5 years). Strain allelic diversity (h) ranged from low to medium in most locations and was most diverse in urban centers where foreign-born population density was also high. Overall, 21.5% of cases among U.S.-born persons and 4.6% among foreign-born persons clustered genotypically and spatiotemporally and involved strains of the Haarlem family. One Haarlem space-time cluster identified in the mostly rural northern region of Florida included US/Canada-born individuals incarcerated at the time of diagnosis; two clusters in the mostly urban southern region of Florida were composed predominantly of foreign-born persons. Both groups had HIV prevalence above twenty percent.Conclusions/SignificanceAlmost five percent of TB cases reported in Florida during 2009–2013 were potentially due to recent transmission. Improvements to TB screening practices among the prison population and recent immigrants are likely to impact TB control. Due to the monomorphic nature of available markers, whole genome sequencing is needed to conclusively delineate recent transmission events between U.S. and foreign-born persons.

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Section: Discussionmentioning

confidence: 92%

Spatiotemporal Clustering of Mycobacterium tuberculosis Complex Genotypes in Florida: Genetic Diversity Segregated by Country of Birth

et al. 2016

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“…Clustering analyses comprise statistical approaches that test whether or not outbreak events are more spatially proximate than would be expected under randomized processes. Spatio-temporal analyses, such as accomplished by implementing a spatial scan statistic [see below; ( 42 , 43 )], evaluate if outbreaks (or other phenomena) cluster in both space and time, thereby shedding light on why clusters form, their size, and their duration. For the purposes of this article, we define spatial models as techniques that predict the spatial distribution of disease risk, or explain the spatio-temporal trends of outbreaks.…”

Section: Computational Approachesmentioning

confidence: 99%

Biothreat Reduction and Economic Development: The Case of Animal Husbandry in Central Asia

Walker

Blackburn

2015

Front. Public Health

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Improving human welfare is a critical global concern, but not always easy to achieve. Complications in this regard have been faced by the states of the Former Soviet Union, where socialist-style economic institutions have disappeared, and the transition to a market economy has been slow in coming. Lack of capital, ethnic conflict, and political instability have at times undermined the institutional reform that would be necessary to enable economic efficiency and development. Nowhere are such challenges more pronounced than in the new nation states of central Asia, including Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan. Here, a severe climate limits agriculture, and industrialization has been inhibited by lack of infrastructure, low levels of human capital, and a scarcity of financial resources. These conditions are aggravated by the fact that the central Asian states are landlocked, far from centers of market demand and capital availability. Despite these daunting barriers, development potential does exist, and the goal of the paper is to consider central Asia’s pastoral economy, with a focus on Kazakhstan, which stands poised to become a regional growth pole. The article pursues its goal as follows. It first addresses the biothreat situation to central Asian livestock herds, the most significant existing impediment to realizing the full market potential of the region’s animal products. Next, it provides an outline of interventions that can reduce risk levels for key biothreats impacting central Asia, namely foot and mouth disease (FMD), which greatly impacts livestock and prohibits export, and Brucellosis, a bacterial zoonosis with high incidence in both humans and livestock in the region. Included is an important success story involving the FMD eradication programs in Brazil, which enabled an export boom in beef. After this comes a description of the epidemiological situation in Kazakhstan; here, the article considers the role of wildlife in acting as a possible disease reservoir, which presents a conservation issue for the Kazakhstani case. This is followed by a discussion of the role of science in threat reduction, particularly with respect to the potential offered by geospatial technologies to improve our epidemiological knowledge base. The article concludes with an assessment of the research that would be necessary to identify feasible pathways to develop the economic potential of central Asian livestock production as changes in policy are implemented and livestock health improves.

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“…Areas with neutral or slightly alkaline soil, elevated temperatures, and humidity have been reported to have a high incidence of anthrax outbreaks [ 7 ]. In the USA, clusters of anthrax cases have been reported in the east, west, and south of Georgia [ 13 ]. In addition, several studies indicate that the disease mainly occurs in low-lying depressions [ 4 , 6 , 14 ].…”

Section: Introductionmentioning

confidence: 99%

Spatial Patterns of Anthrax Outbreaks and Cases among Livestock in Lesotho, 2005–2016

Lepheana

Oguttu

Qekwana

2020

IJERPH

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Background: Although anthrax occurs globally, the burden of the disease remains particularly high in Africa. Furthermore, the disease anthrax has significant public health and economic implications. However, sufficient attention has not been given to the geographic distribution of anthrax outbreaks and cases in Lesotho. Therefore, this study investigates the spatial patterns of anthrax outbreaks and cases among livestock in Lesotho from 2005 to 2016. Methods: A cross-sectional study design was adopted to realise the objectives of this study using retrospective data of anthrax outbreaks and cases recorded by the Department of Livestock Services (DLS) between 2005 and 2016. Anthrax outbreaks were geo-coded at village level and aggregated at district level. Proportions and 95% CI of anthrax outbreaks and cases by village and district were calculated. Cartographic maps displaying the distribution of anthrax outbreaks and cases at village and district level were constructed. Results: A total of 38 outbreaks were reported over the study period, and they were clustered in the Lowlands districts of Lesotho. Most outbreaks (52.6%, 20/38) in livestock were reported in the Maseru district. The Leribe district reported the lowest proportions of outbreaks (5.3%, 2/38) and cases (0.6%, 3/526). At the village level, 18% (7/38) of outbreaks were in Maseru Urban, followed by Ratau (16%, 6/38) and Mofoka (13%, 5/38). The Maseru district reported the highest (1.3%, 369/29,070) proportion of cases followed by Mafeteng (0.9%, 73/8530). The village with the most cases was Kolo (10.5%, 21/200), followed by Thaba-Chitja (7.7%, 33/430). Conclusion: Anthrax outbreaks and cases exclusively occur in the Lowlands districts of Lesotho, with villages such as Mahobong, Pitseng, Kolo, and Thaba-Chitja having a higher risk of anthrax disease. Findings of the present study have serious public health implications in light of the fact that between 2003 and 2008 Lesotho’s main abattoir was closed; hence, most of the meat in Lesotho was imported and/or sourced from the informal slaughter facilities. Much larger studies are needed to further investigate factors contributing to spatial disparities in anthrax outbreaks and cases observed in this study. Findings of the present study can be used to guide the formulation of a policy on prevention and control of anthrax in Lesotho.

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Identifying hotspots of human anthrax transmission using three local clustering techniques

Abstract: 2016-11-02T18:49:00

Cited by 31 publications

References 44 publications

Spatiotemporal Clustering of Mycobacterium tuberculosis Complex Genotypes in Florida: Genetic Diversity Segregated by Country of Birth

Spatiotemporal Clustering of Mycobacterium tuberculosis Complex Genotypes in Florida: Genetic Diversity Segregated by Country of Birth

Biothreat Reduction and Economic Development: The Case of Animal Husbandry in Central Asia

Spatial Patterns of Anthrax Outbreaks and Cases among Livestock in Lesotho, 2005–2016

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