The global distribution of Bacillus anthracis and associated anthrax risk to humans, livestock and wildlife.

Bacillus anthracis is a spore-forming, Gram-positive bacterium responsible for anthrax, an acute infection that most significantly affects grazing livestock and wild ungulates, but also poses a threat to human health. The geographic extent of B. anthracis is poorly understood, despite multi-decade research on anthrax epizootic and epidemic dynamics; many countries have limited or inadequate surveillance systems, even within known endemic regions. Here, we compile a global occurrence dataset of human, livestock and wildlife anthrax outbreaks. With these records, we use boosted regression trees to produce a map of the global distribution of B. anthracis as a proxy for anthrax risk. We estimate that 1.83 billion people (95% credible interval (CI): 0.59-4.16 billion) live within regions of anthrax risk, but most of that population faces little occupational exposure. More informatively, a global total of 63.8 million poor livestock keepers (95% CI: 17.5-168.6 million) and 1.1 billion livestock (95% CI: 0.4-2.3 billion) live within vulnerable regions. Human and livestock vulnerability are both concentrated in rural rainfed systems throughout arid and temperate land across Eurasia, Africa and North America. We conclude by mapping where anthrax risk could disrupt sensitive conservation efforts for wild ungulates that coincide with anthrax-prone landscapes

Analysing the spatial patterns of livestock anthrax in Kazakhstan in relation to environmental factors: a comparison of local (Gi*) and morphology cluster statistics

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 (Gi*) statistic and a multidirectional optimal ecotope algorithm (AMOEBA) were compared using 1st, 2nd, and 3rd order Rook contiguity matrices. Multivariate statistical tests were used to evaluate the environmental signatures between clusters and non-clusters from the AMOEBA and Gi* 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, Gi* 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 Mann-Whitney 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 Gi* clusters. In general, AMOEBA predicted more irregularly shaped clusters of outbreaks in both livestock groups, while Gi* tended to predicted 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

Evidence of local persistence of human anthrax in the country of georgia associated with environmental and anthropogenic factors.

BACKGROUND: Anthrax is a soil-borne disease caused by the bacterium Bacillus anthracis and is considered a neglected zoonosis. In the country of Georgia, recent reports have indicated an increase in the incidence of human anthrax. Identifying sub-national areas of increased risk may help direct appropriate public health control measures. The purpose of this study was to evaluate the spatial distribution of human anthrax and identify environmental/anthropogenic factors associated with persistent clusters. METHODS/FINDINGS: A database of human cutaneous anthrax in Georgia during the period 2000-2009 was constructed using a geographic information system (GIS) with case data recorded to the community location. The spatial scan statistic was used to identify persistence of human cutaneous anthrax. Risk factors related to clusters of persistence were modeled using a multivariate logistic regression. Areas of persistence were identified in the southeastern part of the country. Results indicated that the persistence of human cutaneous anthrax showed a strong positive association with soil pH and urban areas. CONCLUSIONS/SIGNIFICANCE: Anthrax represents a persistent threat to public and veterinary health in Georgia. The findings here showed that the local level heterogeneity in the persistence of human cutaneous anthrax necessitates directed interventions to mitigate the disease. High risk areas identified in this study can be targeted for public health control measures such as farmer education and livestock vaccination campaigns

Household-Level Spatiotemporal Patterns of Incidence of Cholera, Haiti, 2011

A cholera outbreak began in Haiti during October, 2010. Spatiotemporal patterns of household-level cholera in Ouest Department showed that the initial clusters tended to follow major roadways; subsequent clusters occurred further inland. Our data highlight transmission pathway complexities and the need for case and household-level analysis to understand disease spread and optimize interventions

Seroprevalence of Brucellosis in Livestock within Three Endemic Regions of the Country of Georgia

Brucellosis is the one of most common livestock zoonoses in Georgia, resulting in significant economic losses. Livestock were sampled in three regions of Georgia (Kakheti, Kvemo Kartli, Imereti). Districts that historically reported high numbers of brucellosis related morbidity were selected for serological, bacteriological and molecular surveys. Surveying efforts yielded samples from 10,819 large and small ruminants. In total, 735 serological tests were positive on Rose Bengal and 33 bacterial isolates were recovered and identified as Brucella melitensis or Brucella abortus by microbiology and AMOS-PCR. A Bayesian framework was implemented to estimate the true prevalence of the disease given an imperfect diagnostic test. Regional posterior median true prevalence estimates ranged from 2.7% (95% CI: 1.4, 7.2) in Kvemo Kartli, 0.8% (95% CI: 0.0, 3.6) in Kakheti, to an estimate of 0.6% (95% CI: 0.0, 2.9) in Imereti. Accurate and efficient surveillance of brucellosis is not only of economic value, but also informs efforts to reduce the disease impact on the human population

National reporting of human cutaneous anthrax in Georgia by year and incidence per 1 million population.

<p>National reporting of human cutaneous anthrax in Georgia by year and incidence per 1 million population.</p

Spatial clustering of human cutaneous anthrax.

<p>Village level clustering was identified during the period 2000 to 2004 (A) and 2005 to 2009 (B). Star symbols represent cluster centers, red dots represent villages that were part of spatial cluster, and grey dots represent villages that were not part of a spatial cluster. Buffers of clusters are represented in kilometers (km).</p