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Smolko P, Seidel D, Pybus M, Hubbs A, Ball M, Merrill E. Spatio-temporal changes in chronic wasting disease risk in wild deer during 14 years of surveillance in Alberta, Canada. Prev Vet Med 2021; 197:105512. [PMID: 34740023 DOI: 10.1016/j.prevetmed.2021.105512] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 10/15/2021] [Accepted: 10/18/2021] [Indexed: 11/18/2022]
Abstract
Disease risk modeling is a key first step to understand the spatio-temporal dynamics of wildlife disease and to direct cost-effective surveillance and management. In Alberta, active surveillance for chronic wasting disease (CWD) in wild cervids began in 1998 with the first case detected in free-ranging cervids in 2005. Following the detection, a herd reduction program was implemented during 2005-2008 and in 2006 the ongoing hunter-based CWD Surveillance Program became mandatory in high-risk Wildlife Management Units (WMU). We used data collected during the CWD surveillance program to 1) document growth in sex-specific CWD prevalence (proportion of deer in sample that is CWD-positive) in hunter-harvest deer in 6 WMUs consistently monitored from 2006 to 2018, 2) document landscape features associated with where CWD-positive compared to CWD-negative deer were removed during hunter harvest and herd reduction in an early (2005-2012) and in a late period (2013-2017), and 3) to map the spatial risk of harvesting a deer infected with CWD in the prairie parklands of Alberta. In the 6 continuously monitored WMUs, risk of a harvested deer being CWD positive increased from 2006 to 2018 with CWD prevalence remaining highest in male mule deer whereas overall growth rate in CWD prevalence was greater in female mule deer, but similar to male white-tailed deer. We found no evidence that the 3-year herd reduction program conducted immediately after CWD was first detected affected the rate at which CWD grew over the course of the invasion. Risk of deer being CWD-positive was the highest in animals taken near small stream drainages and on soils with low organic carbon content in the early period, whereas risk became highest in areas of agriculture especially when far from large river drainages where deer often concentrate in isolated woody patches. The change in the influence of proximity to known CWD-positive cases suggested the disease was initially patchy but became more spatially homogeneous over time. Our results indicate that a targeted-removal program will remove more CWD positive animals compared to hunter harvest. However, the discontinuation of targeted removals during our research program, restricted our ability to assess its long term impact on CWD prevalence.
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Affiliation(s)
- Peter Smolko
- University of Alberta, Department of Biological Sciences, Edmonton, AB T6G 2E9, Canada; Technical University in Zvolen, Department of Applied Zoology and Wildlife Management, 960 01, Zvolen, Slovakia
| | - Dana Seidel
- Department of Environmental Science, Policy, & Management, University of California, Berkeley, CA, USA
| | - Margo Pybus
- University of Alberta, Department of Biological Sciences, Edmonton, AB T6G 2E9, Canada; Alberta Fish and Wildlife Division, Government of Alberta, Edmonton, AB T6H 4P2, Canada
| | - Anne Hubbs
- Alberta Fish and Wildlife Division, Government of Alberta, Edmonton, AB T6H 4P2, Canada
| | - Mark Ball
- Alberta Fish and Wildlife Division, Government of Alberta, Edmonton, AB T6H 4P2, Canada
| | - Evelyn Merrill
- University of Alberta, Department of Biological Sciences, Edmonton, AB T6G 2E9, Canada.
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Inferring Chronic Wasting Disease Incidence from Prevalence Data. J Wildl Dis 2021; 57:718-721. [PMID: 33961047 DOI: 10.7589/jwd-d-20-00216] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 01/29/2021] [Indexed: 11/20/2022]
Abstract
Incidence of chronic wasting disease infection showed strong, positive correlation (r≥0.944) with apparent prevalence among female and male mule deer (Odocoileus hemionus) in seven herds previously studied in Colorado and Wyoming, US. With attention to monitoring method consistency and context, inferring that observed prevalence trends reflect underlying epidemic dynamics in mule deer herds appears justifiable.
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HUNTING PRESSURE MODULATES PRION INFECTION RISK IN MULE DEER HERDS. J Wildl Dis 2021; 56:781-790. [PMID: 33600602 DOI: 10.7589/jwd-d-20-00054] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 06/19/2020] [Indexed: 11/20/2022]
Abstract
The emergence of chronic wasting disease, an infectious prion disease of multiple deer species, has motivated international calls for sustainable, socially accepted control measures. Here, we describe long-term, spatially replicated relationships in Colorado, US, mule deer (Odocoileus hemionus) herds that show hunting pressure can modulate apparent epidemic dynamics as reflected by prevalence trends. Across 12 areas in Colorado studied between 2002-18, those with the largest declines in annual hunting license numbers (pressure) showed the largest increases in the proportion of infected adult (≥2-yr-old) male deer killed by hunters (prevalence); prevalence trends were comparatively flat in most areas where license numbers had been maintained or increased. The mean number of licenses issued in the 2 yr prior best explained observed patterns: increasing licenses lowered subsequent risk of harvesting an infected deer, and decreasing licenses increased that risk. Our findings suggest that harvesting mule deer with sufficient hunting pressure might control chronic wasting disease-especially when prevalence is low-but that harvest prescriptions promoting an abundance of mature male deer contribute to the exponential growth of epidemics.
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Mysterud A, Viljugrein H, Rolandsen CM, Belsare AV. Harvest strategies for the elimination of low prevalence wildlife diseases. ROYAL SOCIETY OPEN SCIENCE 2021; 8:210124. [PMID: 33959374 PMCID: PMC8074915 DOI: 10.1098/rsos.210124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 02/03/2021] [Indexed: 06/12/2023]
Abstract
The intensive harvesting of hosts is often the only practicable strategy for controlling emerging wildlife diseases. Several harvesting approaches have been explored theoretically with the objective of lowering transmission rates, decreasing the transmission period or specifically targeting spatial disease clusters or high-risk demographic groups. Here, we present a novel model-based approach to evaluate alternative harvest regimes, in terms of demographic composition and rates, intended to increase the probability to remove all infected individuals in the population during the early phase of an outbreak. We tested the utility of the method for the elimination of chronic wasting disease based on empirical data for reindeer (Rangifer tarandus) in Norway, in populations with (Nordfjella) and without (Hardangervidda) knowledge about exact disease prevalence and population abundance. Low and medium harvest intensities were unsuccessful in eliminating the disease, even at low prevalence. High-intensity harvesting had a high likelihood of eliminating the disease, but probability was strongly influenced by the disease prevalence. We suggest that the uncertainty about disease prevalence can be mitigated by using an adaptive management approach: forecast from models after each harvest season with updated data, derive prevalence estimates and forecast further harvesting. We identified the problems arising from disease surveillance with large fluctuations in harvesting pressure and hence sample sizes. The elimination method may be suitable for pathogens that cause long-lasting infections and with slow epidemic growth, but the method should only be attempted if there is a low risk of reinfection, either by a new disease introduction event (e.g. dispersing hosts) or due to environmental reservoirs. Our simulations highlighted the short time window when such a strategy is likely to be successful before approaching near complete eradication of the population.
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Affiliation(s)
- Atle Mysterud
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, PO Box 1066, Blindern, 0316 Oslo, Norway
| | - Hildegunn Viljugrein
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, PO Box 1066, Blindern, 0316 Oslo, Norway
- Norwegian Veterinary Institute, PO Box 750 Sentrum, 0106 Oslo, Norway
| | - Christer M. Rolandsen
- Norwegian Institute for Nature Research (NINA), PO Box 5685 Torgarden, 7485 Trondheim, Norway
| | - Aniruddha V. Belsare
- Boone and Crockett Quantitative Wildlife Center, Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI, USA
- Department of Biology, Emory College of Arts and Sciences, Emory University, Atlanta, GA, USA
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Mysterud A, Edmunds DR. A review of chronic wasting disease in North America with implications for Europe. EUR J WILDLIFE RES 2019. [DOI: 10.1007/s10344-019-1260-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Wood ME, Griebel P, Huizenga ML, Lockwood S, Hansen C, Potter A, Cashman N, Mapletoft JW, Napper S. Accelerated onset of chronic wasting disease in elk (Cervus canadensis) vaccinated with a PrP Sc-specific vaccine and housed in a prion contaminated environment. Vaccine 2018; 36:7737-7743. [PMID: 30414779 DOI: 10.1016/j.vaccine.2018.10.057] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 10/07/2018] [Accepted: 10/14/2018] [Indexed: 10/27/2022]
Abstract
Chronic wasting disease (CWD) is a fatal prion disease affecting multiple cervid species. Effective management tools for this disease, particularly in free-ranging populations, are currently limited. We evaluated a novel CWD vaccine in elk (Cervus canadensis) naturally exposed to CWD through a prion-contaminated environment. The vaccine targets a YYR disease-specific epitope to induce antibody responses specific to the misfolded (PrPSc) conformation. Female elk calves (n = 41) were captured from western Wyoming and transported to the Thorne-Williams Wildlife Research Center where CWD has been documented since 1979. Elk were held in contaminated pens for 14 to 20 days before being alternately assigned to either a vaccine (n = 21) or control group (n = 20). Vaccinated animals initially received two vaccinations approximately 42 days apart and annual vaccinations thereafter. Vaccination induced elevated YYR-specific antibody titers in all animals. Elk were genotyped for the prion protein gene at codon 132, monitored for clinical signs of CWD through daily observation, for disease status through periodic biopsy of rrectoanal mucosa-associated lympoid tissue (RAMALT), and monitored for YYR-specific serum antibody titres. Mean survival of vaccinated elk with the 132MM genotype (n = 15) was significantly shorter (800 days) than unvaccinated elk (n = 13) of the same genotype (1062 days; p = 0.003). Mean days until positive RAMALT biopsy for 132MM vaccinated elk (6 7 8) were significantly shorter than unvaccinated 132MM elk (990; p = 0.012). There was, however, no significant difference in survival between vaccinated (n = 4) and control (n = 5) elk with the 132ML genotype (p = 0.35) or in timing of positive RAMALT biopsies of 132ML elk (p = 0.66). There was no strong (p = 0.17) correlation between YYR-specific antibody titers and survival time. Determining the mechanism by which this vaccine accelerates onset of CWD will be important to direct further CWD vaccine research.
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Affiliation(s)
- Mary E Wood
- Wyoming Game and Fish Department, 1212 South Adams St, Laramie, WY, USA; Wyoming Game and Fish Department, Thorne-Williams Wildlife Research Center, 2362 HWY 34 Wheatland, WY, USA.
| | - Philip Griebel
- Vaccine and Infectious Disease Organization-International Vaccine Research Center, University of Saskatchewan, 120 Veterinary Road, S7N 5E3 Saskatoon, Saskatchewan, Canada; School of Public Health, University of Saskatchewan, 104 Clinic Place, S7N 2Z4 Saskatoon, Saskatchewan, Canada
| | - Matthew L Huizenga
- Wyoming Game and Fish Department, Thorne-Williams Wildlife Research Center, 2362 HWY 34 Wheatland, WY, USA
| | - Samuel Lockwood
- Wyoming Game and Fish Department, Thorne-Williams Wildlife Research Center, 2362 HWY 34 Wheatland, WY, USA
| | - Cole Hansen
- Wyoming Game and Fish Department, Thorne-Williams Wildlife Research Center, 2362 HWY 34 Wheatland, WY, USA
| | - Andrew Potter
- Vaccine and Infectious Disease Organization-International Vaccine Research Center, University of Saskatchewan, 120 Veterinary Road, S7N 5E3 Saskatoon, Saskatchewan, Canada
| | - Neil Cashman
- Department of Neurology, University of British Columbia, S192 - 2211 Wesbrook Mall, V6T 2B5 Vancouver, BC, Canada
| | - John W Mapletoft
- Pan-Provincial Vaccine Enterprise Inc. University of Saskatchewan, 120 Veterinary Road, S7N 5E3 Saskatoon, Saskatchewan, Canada
| | - Scott Napper
- Vaccine and Infectious Disease Organization-International Vaccine Research Center, University of Saskatchewan, 120 Veterinary Road, S7N 5E3 Saskatoon, Saskatchewan, Canada; Department of Biochemistry, University of Saskatchewan, 107 Wiggins Road, S7N 5E5 Saskatoon, Saskatchewan, Canada
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A penalized simulated maximum likelihood method to estimate parameters for SDEs with measurement error. Comput Stat 2018. [DOI: 10.1007/s00180-018-0846-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Benestad SL, Telling GC. Chronic wasting disease: an evolving prion disease of cervids. HANDBOOK OF CLINICAL NEUROLOGY 2018; 153:135-151. [PMID: 29887133 DOI: 10.1016/b978-0-444-63945-5.00008-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Chronic wasting disease (CWD) is a relatively new and burgeoning prion epidemic of deer, elk, reindeer, and moose, which are members of the cervid family. While the disease was first described in captive deer, its subsequent discovery in various species of free-ranging animals makes it the only currently recognized prion disorder of both wild and farmed animals. In addition to its expanding range of host species, CWD continues to spread from North America to new geographic areas, including South Korea, and most recently Norway, marking the first time this disease was detected in Europe. Its unparalleled efficiency of contagious transmission, combined with high densities of deer in certain areas, complicates strategies for controlling CWD, raising concerns about its potential for spread to new species. Because there is a high prevalence of CWD in deer and elk, which are commonly hunted and consumed by humans, and since prions from cattle with bovine spongiform encephalopathy have been transmitted to humans causing variant Creutzfeldt-Jakob disease, the possibility of zoonotic transmission of CWD is particularly concerning. Here we review the clinical and pathologic features of CWD and its disturbing epidemiology, and discuss features that affect its transmission, including genetic susceptibility, pathogenesis, and agent strain variability. Finally, we discuss evidence that speaks to the potential for zoonotic transmission of this emerging disease.
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Affiliation(s)
| | - Glenn C Telling
- Prion Research Center (PRC) and the Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, United States.
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Moreno JA, Telling GC. Molecular Mechanisms of Chronic Wasting Disease Prion Propagation. Cold Spring Harb Perspect Med 2018; 8:cshperspect.a024448. [PMID: 28193766 DOI: 10.1101/cshperspect.a024448] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Prion disease epidemics, which have been unpredictable recurrences, are of significant concern for animal and human health. Examples include kuru, once the leading cause of death among the Fore people in Papua New Guinea and caused by mortuary feasting; bovine spongiform encephalopathy (BSE) and its subsequent transmission to humans in the form of variant Creutzfeldt-Jakob disease (vCJD), and repeated examples of large-scale prion disease epidemics in animals caused by contaminated vaccines. The etiology of chronic wasting disease (CWD), a relatively new and burgeoning prion epidemic in deer, elk, and moose (members of the cervid family), is more enigmatic. The disease was first described in captive and later in wild mule deer and subsequently in free-ranging as well as captive Rocky Mountain elk, white-tailed deer, and most recently moose. It is therefore the only recognized prion disorder of both wild and captive animals. In addition to its expanding range of hosts, CWD continues to spread to new geographical areas, including recent cases in Norway. The unparalleled efficiency of the contagious transmission of the disease combined with high densities of deer in certain areas of North America complicates strategies for controlling CWD and raises concerns about its potential spread to new species. Because there is a high prevalence of CWD in deer and elk, which are commonly hunted and consumed by humans, the possibility of zoonotic transmission is particularly concerning. Here, we review the current status of naturally occurring CWD and describe advances in our understanding of its molecular pathogenesis, as shown by studies of CWD prions in novel in vivo and in vitro systems.
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Affiliation(s)
- Julie A Moreno
- Prion Research Center (PRC) and the Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, Colorado 80525
| | - Glenn C Telling
- Prion Research Center (PRC) and the Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, Colorado 80525
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EVALUATION OF A TEST AND CULL STRATEGY FOR REDUCING PREVALENCE OF CHRONIC WASTING DISEASE IN MULE DEER ( ODOCOILEUS HEMIONUS). J Wildl Dis 2018; 54:511-519. [PMID: 29667874 DOI: 10.7589/2018-01-015] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We evaluated a test and cull strategy for lowering chronic wasting disease (CWD) prevalence in a naturally-infected, free-ranging mule deer ( Odocoileus hemionus) herd wintering in the town of Estes Park, Colorado, US and in nearby Rocky Mountain National Park. We tested 48-68% of the estimated number of adult (≥1 yr old) deer annually for 5 yr via tonsil biopsy immunohistochemistry (IHC), collecting 1,251 samples from >700 individuals and removing IHC-positive deer. Among males, CWD prevalence during the last 3 yr of selective culling was lower (one-sided Fisher's exact test P=0.014) than in the period prior. In contrast, CWD prevalence among females before culling and after culling were equivalent ( P=0.777). Relatively higher annual testing of males (mean 77%) compared to females (mean 51%) might have contributed to differences seen in responses to management. A more intensive and sustained effort or modified spatial approach might have reduced prevalence more consistently in both sexes. Limitations of this technique in wider management application include cost and labor as well as property access and animal tolerance to repeated capture. However, elements of this approach could potentially be used to augment harvest-based disease management.
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DeVivo MT, Edmunds DR, Kauffman MJ, Schumaker BA, Binfet J, Kreeger TJ, Richards BJ, Schätzl HM, Cornish TE. Endemic chronic wasting disease causes mule deer population decline in Wyoming. PLoS One 2017; 12:e0186512. [PMID: 29049389 PMCID: PMC5648191 DOI: 10.1371/journal.pone.0186512] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 10/03/2017] [Indexed: 11/19/2022] Open
Abstract
Chronic wasting disease (CWD) is a fatal transmissible spongiform encephalopathy affecting white-tailed deer (Odocoileus virginianus), mule deer (Odocoileus hemionus), Rocky Mountain elk (Cervus elaphus nelsoni), and moose (Alces alces shirasi) in North America. In southeastern Wyoming average annual CWD prevalence in mule deer exceeds 20% and appears to contribute to regional population declines. We determined the effect of CWD on mule deer demography using age-specific, female-only, CWD transition matrix models to estimate the population growth rate (λ). Mule deer were captured from 2010-2014 in southern Converse County Wyoming, USA. Captured adult (≥ 1.5 years old) deer were tested ante-mortem for CWD using tonsil biopsies and monitored using radio telemetry. Mean annual survival rates of CWD-negative and CWD-positive deer were 0.76 and 0.32, respectively. Pregnancy and fawn recruitment were not observed to be influenced by CWD. We estimated λ = 0.79, indicating an annual population decline of 21% under current CWD prevalence levels. A model derived from the demography of only CWD-negative individuals yielded; λ = 1.00, indicating a stable population if CWD were absent. These findings support CWD as a significant contributor to mule deer population decline. Chronic wasting disease is difficult or impossible to eradicate with current tools, given significant environmental contamination, and at present our best recommendation for control of this disease is to minimize spread to new areas and naïve cervid populations.
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Affiliation(s)
- Melia T. DeVivo
- Department of Veterinary Sciences, University of Wyoming, Laramie, Wyoming, United States of America
- * E-mail:
| | - David R. Edmunds
- Natural Resource Ecology Laboratory, Colorado State University/US Geological Survey, Fort Collins, Colorado, United States of America
| | - Matthew J. Kauffman
- U.S. Geological Survey, Wyoming Cooperative Fish and Wildlife Research Unit, Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming, United States of America
| | - Brant A. Schumaker
- Department of Veterinary Sciences, University of Wyoming, Laramie, Wyoming, United States of America
| | - Justin Binfet
- Wyoming Game and Fish Department, Casper, Wyoming, United States of America
| | - Terry J. Kreeger
- Wyoming Game and Fish Department, Wheatland, Wyoming, United States of America
| | - Bryan J. Richards
- U.S. Geological Survey, National Wildlife Health Center, Madison, Wisconsin, United States of America
| | - Hermann M. Schätzl
- Department of Comparative Biology & Experimental Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Todd E. Cornish
- Department of Veterinary Sciences, University of Wyoming, Laramie, Wyoming, United States of America
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Abstract
Chronic wasting disease (CWD) affects cervids and is the only known prion disease readily transmitted among free-ranging wild animal populations in nature. The increasing spread and prevalence of CWD among cervid populations threaten the survival of deer and elk herds in North America, and potentially beyond. This review focuses on prion ecology, specifically that of CWD, and the current understanding of the role that the environment may play in disease propagation. We recount the discovery of CWD, discuss the role of the environment in indirect CWD transmission, and consider potentially relevant environmental reservoirs and vectors. We conclude by discussing how understanding the environmental persistence of CWD lends insight into transmission dynamics and potential management and mitigation strategies.
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Uehlinger FD, Johnston AC, Bollinger TK, Waldner CL. Systematic review of management strategies to control chronic wasting disease in wild deer populations in North America. BMC Vet Res 2016; 12:173. [PMID: 27549119 PMCID: PMC4994292 DOI: 10.1186/s12917-016-0804-7] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Accepted: 08/18/2016] [Indexed: 01/01/2023] Open
Abstract
Background Chronic wasting disease (CWD) is a contagious, fatal prion disease affecting cervids in a growing number of regions across North America. Projected deer population declines and concern about potential spread of CWD to other species warrant strategies to manage this disease. Control efforts to date have been largely unsuccessful, resulting in continuing spread and increasing prevalence. This systematic review summarizes peer-reviewed published reports describing field-applicable CWD control strategies in wild deer populations in North America using systematic review methods. Ten databases were searched for peer-reviewed literature. Following deduplication, relevance screening, full-text appraisal, subject matter expert review and qualitative data extraction, nine references were included describing four distinct management strategies. Results Six of the nine studies used predictive modeling to evaluate control strategies. All six demonstrated one or more interventions to be effective but results were dependant on parameters and assumptions used in the model. Three found preferential removal of CWD infected deer to be effective in reducing CWD prevalence; one model evaluated a test and slaughter strategy, the other selective removal of infected deer by predators and the third evaluated increased harvest of the sex with highest prevalence (males). Three models evaluated non-selective harvest of deer. There were only three reports that examined primary data collected as part of observational studies. Two of these studies supported the effectiveness of intensive non-selective culling; the third study did not find a difference between areas that were subjected to culling and those that were not. Seven of the nine studies were conducted in the United States. Conclusions This review highlights the paucity of evaluated, field-applicable control strategies for CWD in wild deer populations. Knowledge gaps in the complex epidemiology of CWD and the intricacies inherent to prion diseases currently pose significant challenges to effective control of this disease in wild deer in North America. Electronic supplementary material The online version of this article (doi:10.1186/s12917-016-0804-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- F D Uehlinger
- Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, S7N 5B4, Canada.
| | - A C Johnston
- Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, S7N 5B4, Canada
| | - T K Bollinger
- Canadian Wildlife Health Cooperative, Department of Veterinary Pathology, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, S7N 5B4, Canada
| | - C L Waldner
- Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, S7N 5B4, Canada
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