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Almberg ES, Cross PC, Johnson CJ, Heisey DM, Richards BJ. Modeling routes of chronic wasting disease transmission: environmental prion persistence promotes deer population decline and extinction. PLoS One 2011; 6:e19896. [PMID: 21603638 PMCID: PMC3094393 DOI: 10.1371/journal.pone.0019896] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Accepted: 04/19/2011] [Indexed: 01/26/2023] Open
Abstract
Chronic wasting disease (CWD) is a fatal disease of deer, elk, and moose transmitted through direct, animal-to-animal contact, and indirectly, via environmental contamination. Considerable attention has been paid to modeling direct transmission, but despite the fact that CWD prions can remain infectious in the environment for years, relatively little information exists about the potential effects of indirect transmission on CWD dynamics. In the present study, we use simulation models to demonstrate how indirect transmission and the duration of environmental prion persistence may affect epidemics of CWD and populations of North American deer. Existing data from Colorado, Wyoming, and Wisconsin's CWD epidemics were used to define plausible short-term outcomes and associated parameter spaces. Resulting long-term outcomes range from relatively low disease prevalence and limited host-population decline to host-population collapse and extinction. Our models suggest that disease prevalence and the severity of population decline is driven by the duration that prions remain infectious in the environment. Despite relatively low epidemic growth rates, the basic reproductive number, R(0), may be much larger than expected under the direct-transmission paradigm because the infectious period can vastly exceed the host's life span. High prion persistence is expected to lead to an increasing environmental pool of prions during the early phases (i.e. approximately during the first 50 years) of the epidemic. As a consequence, over this period of time, disease dynamics will become more heavily influenced by indirect transmission, which may explain some of the observed regional differences in age and sex-specific disease patterns. This suggests management interventions, such as culling or vaccination, will become increasingly less effective as CWD epidemics progress.
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Affiliation(s)
- Emily S Almberg
- Northern Rocky Mountain Science Center, United States Geological Survey, Bozeman, Montana, United States of America.
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Waller LA. Bridging gaps between statistical and mathematical modeling in ecology. Ecology 2011; 91:3500-2; discussion 3503-14. [PMID: 21302823 DOI: 10.1890/10-0432.1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Lance A Waller
- Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, 1518 Clifton Road NE, Atlanta, Georgia 30322, USA.
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Cullingham CI, Nakada SM, Merrill EH, Bollinger TK, Pybus MJ, Coltman DW. Multiscale population genetic analysis of mule deer (Odocoileus hemionus hemionus) in western Canada sheds new light on the spread of chronic wasting disease. CAN J ZOOL 2011. [DOI: 10.1139/z10-104] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To successfully manage wildlife diseases, it is necessary to understand factors that influence spread. One approach is to analyze host movement and social structure, as these behaviors can be associated with the probability of transmission. Some populations of mule deer ( Odocoileus hemionus hemionus (Rafinesque, 1817)) in western Canada are infected with chronic wasting disease (CWD), a transmissible and fatal neurodegenerative disease. We used population analysis of spatial genetic structure of mule deer at broad and local scales to understand factors that influence spread. We genotyped 2535 mule deer sampled from Alberta, Saskatchewan, and portions of British Columbia using 16 microsatellite loci. We found weak genetic structure at broad spatial scales (overall FST = 0.008) that was well defined by geographic distance, indicating the risk of CWD spread from the focus of infection will decline gradually with increasing distance, but there are no barriers to the spread over time. At the local scale of approximately 2 km, elevated relatedness among CWD-infected individuals suggests transmission rates within social groups. Sex-biased spatial autocorrelation in genetic relatedness also indicates that female philopatry underlies the social structure, and therefore transmission among relatives is potentially driving local disease persistence.
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Affiliation(s)
- C. I. Cullingham
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
- Department of Veterinary Pathology, Western College of Veterinary Medicine, Saskatoon, SK S7N 5B4, Canada
- Fish and Wildlife Division, Alberta Sustainable Resource Development, Edmonton, AB T6H 4P2, Canada
| | - S. M. Nakada
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
- Department of Veterinary Pathology, Western College of Veterinary Medicine, Saskatoon, SK S7N 5B4, Canada
- Fish and Wildlife Division, Alberta Sustainable Resource Development, Edmonton, AB T6H 4P2, Canada
| | - E. H. Merrill
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
- Department of Veterinary Pathology, Western College of Veterinary Medicine, Saskatoon, SK S7N 5B4, Canada
- Fish and Wildlife Division, Alberta Sustainable Resource Development, Edmonton, AB T6H 4P2, Canada
| | - T. K. Bollinger
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
- Department of Veterinary Pathology, Western College of Veterinary Medicine, Saskatoon, SK S7N 5B4, Canada
- Fish and Wildlife Division, Alberta Sustainable Resource Development, Edmonton, AB T6H 4P2, Canada
| | - M. J. Pybus
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
- Department of Veterinary Pathology, Western College of Veterinary Medicine, Saskatoon, SK S7N 5B4, Canada
- Fish and Wildlife Division, Alberta Sustainable Resource Development, Edmonton, AB T6H 4P2, Canada
| | - D. W. Coltman
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
- Department of Veterinary Pathology, Western College of Veterinary Medicine, Saskatoon, SK S7N 5B4, Canada
- Fish and Wildlife Division, Alberta Sustainable Resource Development, Edmonton, AB T6H 4P2, Canada
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Rogers KG, Robinson SJ, Samuel MD, Grear DA. Diversity and distribution of white-tailed deer mtDNA lineages in chronic wasting disease (CWD) outbreak areas in southern Wisconsin, USA. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2011; 74:1521-1535. [PMID: 22043912 DOI: 10.1080/15287394.2011.618980] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy affecting North American cervids. Because it is uniformly fatal, the disease is a major concern in the management of white-tailed deer populations. Management programs to control CWD require improved knowledge of deer interaction, movement, and population connectivity that could influence disease transmission and spread. Genetic methods were employed to evaluate connectivity among populations in the CWD management zone of southern Wisconsin. A 576-base-pair region of the mitochondrial DNA of 359 white-tailed deer from 12 sample populations was analyzed. Fifty-eight variable sites were detected within the sequence, defining 43 haplotypes. While most sample populations displayed similar levels of haplotype diversity, individual haplotypes were clustered on the landscape. Spatial clusters of different haplotypes were apparent in distinct ecoregions surrounding CWD outbreak areas. The spatial distribution of mtDNA haplotypes suggests that clustering of the deer matrilineal groups and population connectivity are associated with broad-scale geographic landscape features. These landscape characteristics may also influence the contact rates between groups and therefore the potential spread of CWD; this may be especially true of local disease spread between female social groups. Our results suggest that optimal CWD management needs to be tailored to fit gender-specific dispersal behaviors and regional differences in deer population connectivity. This information will help wildlife managers design surveillance and monitoring efforts based on population interactions and potential deer movement among CWD-affected and unaffected areas.
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Affiliation(s)
- Kip G Rogers
- Department of Forest & Wildlife Ecology, University of Wisconsin, 1630 Linden Drive, Madison, WI 53706, USA
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Heisey DM, Osnas EE, Cross PC, Joly DO, Langenberg JA, Miller MW. Rejoinder: sifting through model space. Ecology 2010. [DOI: 10.1890/10-0894.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Dennis M. Heisey
- USGS, National Wildlife Health Center, Madison, Wisconsin 53711 USA
| | - Erik E. Osnas
- Department of Forest and Wildlife Ecology, University of Wisconsin, 1630 Linden Drive, Madison, Wisconsin 52706 USA
| | - Paul C. Cross
- USGS, Northern Rocky Mountain Science Center, Bozeman, Montana 59717 USA
| | - Damien O. Joly
- Global Health Programs, Wildlife Conservation Society, 1008 Beverly Drive, Nanaimo, British Columbia V9S 2S4 Canada
| | - Julia A. Langenberg
- Wisconsin Department of Natural Resources, 101 South Webster Street, Madison, Wisconsin 53703 USA
| | - Michael W. Miller
- Colorado Division of Wildlife, Wildlife Research Center, 317 West Prospect Road, Fort Collins, Colorado 80526-2097 USA
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