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Dolfi AC, Kausrud K, Rysava K, Champagne C, Huang YH, Barandongo ZR, Turner WC. Season of death, pathogen persistence and wildlife behaviour alter number of anthrax secondary infections from environmental reservoirs. Proc Biol Sci 2024; 291:20232568. [PMID: 38320613 PMCID: PMC10846954 DOI: 10.1098/rspb.2023.2568] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 01/09/2024] [Indexed: 02/08/2024] Open
Abstract
An important part of infectious disease management is predicting factors that influence disease outbreaks, such as R, the number of secondary infections arising from an infected individual. Estimating R is particularly challenging for environmentally transmitted pathogens given time lags between cases and subsequent infections. Here, we calculated R for Bacillus anthracis infections arising from anthrax carcass sites in Etosha National Park, Namibia. Combining host behavioural data, pathogen concentrations and simulation models, we show that R is spatially and temporally variable, driven by spore concentrations at death, host visitation rates and early preference for foraging at infectious sites. While spores were detected up to a decade after death, most secondary infections occurred within 2 years. Transmission simulations under scenarios combining site infectiousness and host exposure risk under different environmental conditions led to dramatically different outbreak dynamics, from pathogen extinction (R < 1) to explosive outbreaks (R > 10). These transmission heterogeneities may explain variation in anthrax outbreak dynamics observed globally, and more generally, the critical importance of environmental variation underlying host-pathogen interactions. Notably, our approach allowed us to estimate the lethal dose of a highly virulent pathogen non-invasively from observational studies and epidemiological data, useful when experiments on wildlife are undesirable or impractical.
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Affiliation(s)
- Amélie C. Dolfi
- Wisconsin Cooperative Wildlife Research Unit, Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | | | - Kristyna Rysava
- Wisconsin Cooperative Wildlife Research Unit, Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Celeste Champagne
- College of Veterinary Medicine, University of Minnesota, Saint Paul, MN 55108, USA
| | - Yen-Hua Huang
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06511, USA
- Institute for Biospheric Studies, Yale University, New Haven, CT 06511, USA
| | - Zoe R. Barandongo
- Wisconsin Cooperative Wildlife Research Unit, Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Wendy C. Turner
- US Geological Survey, Wisconsin Cooperative Wildlife Research Unit, Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI 53706, USA
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Huang YH, Owen-Smith N, Henley MD, Kilian JW, Kamath PL, Ochai SO, van Heerden H, Mfune JKE, Getz WM, Turner WC. Variation in herbivore space use: comparing two savanna ecosystems with different anthrax outbreak patterns in southern Africa. MOVEMENT ECOLOGY 2023; 11:46. [PMID: 37525286 PMCID: PMC10392021 DOI: 10.1186/s40462-023-00385-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Accepted: 04/16/2023] [Indexed: 08/02/2023]
Abstract
BACKGROUND The distribution of resources can affect animal range sizes, which in turn may alter infectious disease dynamics in heterogenous environments. The risk of pathogen exposure or the spatial extent of outbreaks may vary with host range size. This study examined the range sizes of herbivorous anthrax host species in two ecosystems and relationships between spatial movement behavior and patterns of disease outbreaks for a multi-host environmentally transmitted pathogen. METHODS We examined range sizes for seven host species and the spatial extent of anthrax outbreaks in Etosha National Park, Namibia and Kruger National Park, South Africa, where the main host species and outbreak sizes differ. We evaluated host range sizes using the local convex hull method at different temporal scales, within-individual temporal range overlap, and relationships between ranging behavior and species contributions to anthrax cases in each park. We estimated the spatial extent of annual anthrax mortalities and evaluated whether the extent was correlated with case numbers of a given host species. RESULTS Range size differences among species were not linearly related to anthrax case numbers. In Kruger the main host species had small range sizes and high range overlap, which may heighten exposure when outbreaks occur within their ranges. However, different patterns were observed in Etosha, where the main host species had large range sizes and relatively little overlap. The spatial extent of anthrax mortalities was similar between parks but less variable in Etosha than Kruger. In Kruger outbreaks varied from small local clusters to large areas and the spatial extent correlated with case numbers and species affected. Secondary host species contributed relatively few cases to outbreaks; however, for these species with large range sizes, case numbers positively correlated with outbreak extent. CONCLUSIONS Our results provide new information on the spatiotemporal structuring of ranging movements of anthrax host species in two ecosystems. The results linking anthrax dynamics to host space use are correlative, yet suggest that, though partial and proximate, host range size and overlap may be contributing factors in outbreak characteristics for environmentally transmitted pathogens.
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Affiliation(s)
- Yen-Hua Huang
- Wisconsin Cooperative Wildlife Research Unit, Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
| | - Norman Owen-Smith
- Centre for African Ecology, School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Wits, 2050, South Africa
| | - Michelle D Henley
- Applied Behavioural Ecology and Ecosystem Research Unit, School of Environmental Sciences, University of South Africa, Florida, Johannesburg, 1710, South Africa
- Elephants Alive, Ekuthuleni Shareblock Ltd, Hoedspruit, 1380, South Africa
- Department of Philosophy, Faculty of Humanities, University of Johannesburg, Auckland Park, 2006, South Africa
| | - J Werner Kilian
- Etosha Ecological Institute (retired), Etosha National Park, Ministry of Environment, Forestry and Tourism, Okaukuejo, Namibia
| | - Pauline L Kamath
- School of Food and Agriculture, University of Maine, Orono, ME, 04469, USA
| | - Sunday O Ochai
- Department of Veterinary Tropical Diseases, University of Pretoria, Onderstepoort, South Africa
| | - Henriette van Heerden
- Department of Veterinary Tropical Diseases, University of Pretoria, Onderstepoort, South Africa
| | - John K E Mfune
- Department of Environmental Science, University of Namibia, Windhoek, Namibia
| | - Wayne M Getz
- Department of Environmental Science, Policy & Management, University of California, Berkeley, CA, 94704, USA
- School of Mathematical Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Wendy C Turner
- Wisconsin Cooperative Wildlife Research Unit, U.S. Geological Survey, Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI, 53706, USA
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Huang Y, Kausrud K, Hassim A, Ochai SO, van Schalkwyk OL, Dekker EH, Buyantuev A, Cloete CC, Kilian JW, Mfune JKE, Kamath PL, van Heerden H, Turner WC. Environmental drivers of biseasonal anthrax outbreak dynamics in two multihost savanna systems. ECOL MONOGR 2022. [DOI: 10.1002/ecm.1526] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Yen‐Hua Huang
- Wisconsin Cooperative Wildlife Research Unit, Department of Forest and Wildlife Ecology University of Wisconsin‐Madison Madison WI USA
| | - Kyrre Kausrud
- Norwegian Veterinary Institute, PO. box 64 Ås Norway
| | - Ayesha Hassim
- Department of Veterinary Tropical Diseases University of Pretoria Onderstepoort South Africa
| | - Sunday O. Ochai
- Department of Veterinary Tropical Diseases University of Pretoria Onderstepoort South Africa
| | - O. Louis van Schalkwyk
- Department of Veterinary Tropical Diseases University of Pretoria Onderstepoort South Africa
- Office of the State Veterinarian, Department of Agriculture, Land Reform and Rural Development Government of South Africa Skukuza South Africa
- Department of Migration Max Planck Institute of Animal Behavior Radolfzell Germany
| | - Edgar H. Dekker
- Office of the State Veterinarian, Department of Agriculture, Land Reform and Rural Development Government of South Africa Skukuza South Africa
| | - Alexander Buyantuev
- Department of Geography and Planning, University at Albany State University of New York Albany NY USA
| | - Claudine C. Cloete
- Etosha Ecological Institute, Etosha National Park, Ministry of Environment, Forestry and Tourism Namibia
| | - J. Werner Kilian
- Etosha Ecological Institute, Etosha National Park, Ministry of Environment, Forestry and Tourism Namibia
| | - John K. E. Mfune
- Department of Environmental Science University of Namibia Windhoek Namibia
| | | | - Henriette van Heerden
- Department of Veterinary Tropical Diseases University of Pretoria Onderstepoort South Africa
- Faculty of Veterinary Science, Department of Veterinary Tropical Diseases University of Pretoria Onderstepoort South Africa
| | - Wendy C. Turner
- U.S. Geological Survey, Wisconsin Cooperative Wildlife Research Unit, Department of Forest and Wildlife Ecology University of Wisconsin‐Madison Madison WI USA
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