Climatic influence on the anthrax niche in warming northern latitudes

Mg, Walsh; Aw, de Smalen; Sm, Mor

doi:10.1101/219857

Cited by 8 publications

(7 citation statements)

References 52 publications

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“…Our work-and future models incorporating more temporally dynamic environmental predictors of anthrax risk-also set a foundation for investigating how climate and land cover change will impact the distribution and burden of anthrax. Published work suggests that anthrax suitability may decrease in parts of Kazakhstan and the southern United States in a changing climate, but other work anticipates warming-driven emergence at higher latitudes 38,39 . Our study includes recent records from the Yamalo-Nenets area of Russia, where outbreaks in reindeer have led to massive economic losses and threaten the livelihood of traditional pastoralists.…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2019

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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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Section: Discussionmentioning

confidence: 99%

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

et al. 2019

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“…Persistence at higher latitudes may also be better predicted by a slightly different set of climatic constraints on persistence. A recently-published model trained on high-latitude cases in the Northern Hemisphere seems to under-predict known areas of endemism in warmer climates, possibly supporting this explanation 32 . Feedback between local modelling efforts and updated global consensus mapping will improve our overall understanding of what drives different anthrax dynamics, and the likely impact of climate change.…”

mentioning

confidence: 82%

“…Our work also sets a foundation for investigating how climate change will impact the distribution and burden of anthrax. Published work suggests anthrax suitability may decrease in parts of Kazakhstan and the southern United States in a changing climate, but other work anticipates warming-driven emergence at higher latitudes 31, 32 . Our study includes recent records from the Yamalo-Nemets area of Russia, where outbreaks in reindeer have led to massive economic losses and threaten the livelihood of traditional pastoralists.…”

mentioning

confidence: 99%

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

Carlson

Kracalik

Ross

et al. 2018

Preprint

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SummaryBacillus anthracis is a spore-forming, Gram-positive bacterium responsible for anthrax, an acute and commonly lethal infection that most significantly affects grazing livestock, wild ungulates and other herbivorous mammals, but also poses a serious threat to human health1, 2. The geographic extent of B. anthracis endemism is still poorly understood, despite multi-decade research on anthrax epizootic and epidemic dynamics around the world3, 4. Several biogeographic studies have focused on modeling environmental suitability for anthrax at local or national scales5–9, but many countries have limited or inadequate surveillance systems, even within known endemic regions. Here we compile an extensive global occurrence dataset for B. anthracis, drawing on confirmed human, livestock, and wildlife anthrax outbreaks. With these records, we use boosted regression trees10, 11 to produce the first map of the global distribution of B. anthracis as a proxy for anthrax risk. Variable contributions to the model support pre-existing hypotheses that environmental suitability for B. anthracis depends most strongly on soil characteristics such as pH that affect spore persistence, and the extent of seasonal fluctuations in vegetation, which plays a key role in transmission for herbivores12, 13. We apply the global model to estimate that 1.83 billion people (95% credible interval: 0.59—4.16 billion) live within regions of anthrax risk, but most of that population faces little occupational exposure to anthrax. More informatively, a global total of 63.8 million rural 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 risk is concentrated in rural areas, and human and livestock vulnerability are both concentrated in rainfed systems throughout arid and temperate land across Eurasia, Africa, and North America. We conclude by mapping where anthrax risk overlaps with vulnerable wild ungulate populations, and therefore could disrupt sensitive conservation efforts for species like bison, pronghorn, and saiga that coincide with anthrax-prone, mixed-agricultural landscapes. Anthrax is a zoonotic disease caused by the Gram-positive bacterium Bacillus anthracis, a generalist soil-transmitted pathogen found on every inhabited continent14, and several islands including Haiti and parts of the Philippines and Indonesia. Worldwide, an estimated 20,000 to 100,000 cases of anthrax occur annually, mostly in poor rural areas15. In clinical presentations of anthrax, case fatality rates are a function of exposure pathway. Respiratory exposure from spore inhalation is important the context of bioterrorism, but is highly uncommon, and accounts for a negligible fraction of the global burden of anthrax cases. Cutaneous exposure to B. anthracis accounts for the majority of human cases worldwide, and typically presents with low mortality; gastrointestinal exposure accounts for the remainder and presents with intermediate to high fatality rates. Cutaneous and gastrointestinal cases of anthrax are most commonly caused by handling and slaughtering infected livestock, or butchering and eating contaminated meat; untreated gastrointestinal cases likely account for most human mortality from anthrax.14–16

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“…ENM‐based methodology is also incredibly flexible, and can be used in combination with other tools such as resource‐selection functions to improve predictions of how herbivore movement drives cases, or hotspot analyses to study clusters of human and livestock case data (Morris et al ., ; Dougherty et al ., ). These studies can even be used to project future scenarios, including the role climate change will play in altering anthrax transmission (Joyner et al ., ; Walsh, de Smalen & Mor, ).…”

Section: Anthrax: a Case Study In Slow Integrationmentioning

confidence: 99%

Spores and soil from six sides: interdisciplinarity and the environmental biology of anthrax (Bacillus anthracis)

et al. 2018

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Environmentally transmitted diseases are comparatively poorly understood and managed, and their ecology is particularly understudied. Here we identify challenges of studying environmental transmission and persistence with a six-sided interdisciplinary review of the biology of anthrax (Bacillus anthracis). Anthrax is a zoonotic disease capable of maintaining infectious spore banks in soil for decades (or even potentially centuries), and the mechanisms of its environmental persistence have been the topic of significant research and controversy. Where anthrax is endemic, it plays an important ecological role, shaping the dynamics of entire herbivore communities. The complex eco-epidemiology of anthrax, and the mysterious biology of Bacillus anthracis during its environmental stage, have necessitated an interdisciplinary approach to pathogen research. Here, we illustrate different disciplinary perspectives through key advances made by researchers working in Etosha National Park, a long-term ecological research site in Namibia that has exemplified the complexities of the enzootic process of anthrax over decades of surveillance. In Etosha, the role of scavengers and alternative routes (waterborne transmission and flies) has proved unimportant relative to the long-term * Authors for correspondence: (Colin J. Carlson-Tel.: +1 (510) 990 2258; E-mail: ccarlson@sesync.org; Wayne M. Getz-Tel.: +1 510 642 8745; E-mail: wgetz@berkeley.edu; Nils C. Stenseth-Tel.: +47-22854584/+47-22854400; E-mail: n.c.stenseth@ibv.uio.no).Biological Reviews (2018) 000-000 © 2018 Cambridge Philosophical Society 2 Colin J. Carlson and others persistence of anthrax spores in soil and their infection of herbivore hosts. Carcass deposition facilitates green-ups of vegetation to attract herbivores, potentially facilitated by the role of anthrax spores in the rhizosphere. The underlying seasonal pattern of vegetation, and herbivores' immune and behavioural responses to anthrax risk, interact to produce regular 'anthrax seasons' that appear to be a stable feature of the Etosha ecosystem. Through the lens of microbiologists, geneticists, immunologists, ecologists, epidemiologists, and clinicians, we discuss how anthrax dynamics are shaped at the smallest scale by population genetics and interactions within the bacterial communities up to the broadest scales of ecosystem structure. We illustrate the benefits and challenges of this interdisciplinary approach to disease ecology, and suggest ways anthrax might offer insights into the biology of other important pathogens. Bacillus anthracis, and the more recently emerged Bacillus cereus biovar anthracis, share key features with other environmentally transmitted pathogens, including several zoonoses and panzootics of special interest for global health and conservation efforts. Understanding the dynamics of anthrax, and developing interdisciplinary research programs that explore environmental persistence, is a critical step forward for understanding these emerging threats.

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Climatic influence on the anthrax niche in warming northern latitudes

Cited by 8 publications

References 52 publications

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

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

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

Spores and soil from six sides: interdisciplinarity and the environmental biology of anthrax (Bacillus anthracis)

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