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.
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The data that support the findings of this study are available from the corresponding author upon reasonable request and approval from appropriate partner country ministries of health or agriculture.
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The authors thank D. Pigott for helpful tips on BRT modelling; A. Barner for help obtaining World Animal Health Information System vaccination data; S. J. Ryan for general feedback and technical support; G. Simpson for visualization advice; P. Thornton for access to the global dataset of rural poor livestock keepers; T. A. Joyner for data support; and countless livestock and wildlife managers, clinicians and field technicians for contributing data points. Partial funding for this study was provided by NIH 1R01GM117617-01 to J.K.B. and W.M.G. C.J.C. was supported by the National Socio-Environmental Synthesis Center (SESYNC) under funding received from the National Science Foundation DBI-1639145. K.A. was supported in part under the National Science Foundation (NSF EEID grant 1518663). We also thank the Botswana Government Department of Wildlife and National Parks for their assistance and active collaboration on research directed at understanding Botswana anthrax dynamics.
The authors declare no competing interests.
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Carlson, C.J., Kracalik, I.T., Ross, N. et al. The global distribution of Bacillus anthracis and associated anthrax risk to humans, livestock and wildlife. Nat Microbiol 4, 1337–1343 (2019). https://doi.org/10.1038/s41564-019-0435-4
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