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Egan ME, Gorman NT, Crews S, Eichholz MW, Skinner D, Schlichting PE, Rayl ND, Bergman EJ, Ellington EH, Bastille-Rousseau G. Estimating encounter-habitat relationships with scale-integrated resource selection functions. J Anim Ecol 2024; 93:1036-1048. [PMID: 38940070 DOI: 10.1111/1365-2656.14133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 05/27/2024] [Indexed: 06/29/2024]
Abstract
Encounters between animals occur when animals are close in space and time. Encounters are important in many ecological processes including sociality, predation and disease transmission. Despite this, there is little theory regarding the spatial distribution of encounters and no formal framework to relate environmental characteristics to encounters. The probability of encounter could be estimated with resource selection functions (RSFs) by comparing locations where encounters occurred to available locations where they may have occurred, but this estimate is complicated by the hierarchical nature of habitat selection. We developed a method to relate resources to the relative probability of encounter based on a scale-integrated habitat selection framework. This framework integrates habitat selection at multiple scales to obtain an appropriate estimate of availability for encounters. Using this approach, we related encounter probabilities to landscape resources. The RSFs describe habitat associations at four scales, home ranges within the study area, areas of overlap within home ranges, locations within areas of overlap, and encounters compared to other locations, which can be combined into a single scale-integrated RSF. We apply this method to intraspecific encounter data from two species: white-tailed deer (Odocoileus virginianus) and elk (Cervus elaphus) and interspecific encounter data from a two-species system of caribou (Rangifer tarandus) and coyote (Canis latrans). Our method produced scale-integrated RSFs that represented the relative probability of encounter. The predicted spatial distribution of encounters obtained based on this scale-integrated approach produced distributions that more accurately predicted novel encounters than a naïve approach or any individual scale alone. Our results highlight the importance of accounting for the conditional nature of habitat selection in estimating the habitat associations of animal encounters as opposed to 'naïve' comparisons of encounter locations with general availability. This method has direct relevance for testing hypotheses about the relationship between habitat and social or predator-prey behaviour and generating spatial predictions of encounters. Such spatial predictions may be vital for understanding the distribution of encounters driving disease transmission, predation rates and other population and community-level processes.
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Affiliation(s)
- Michael E Egan
- Cooperative Wildlife Research Laboratory, Southern Illinois University, Carbondale, Illinois, USA
| | - Nicole T Gorman
- Cooperative Wildlife Research Laboratory, Southern Illinois University, Carbondale, Illinois, USA
| | - Storm Crews
- Cooperative Wildlife Research Laboratory, Southern Illinois University, Carbondale, Illinois, USA
| | - Michael W Eichholz
- Cooperative Wildlife Research Laboratory, Southern Illinois University, Carbondale, Illinois, USA
| | - Dan Skinner
- Illinois Department of Natural Resources, Division of Wildlife Resources, Springfield, Illinois, USA
| | - Peter E Schlichting
- Illinois Department of Natural Resources, Division of Wildlife Resources, Springfield, Illinois, USA
| | | | - Eric J Bergman
- Colorado Parks and Wildlife, Fort Collins, Colorado, USA
| | - E Hance Ellington
- Department of Wildlife Ecology and Conservation, Range Cattle Research and Education Center, University of Florida, Ona, Florida, USA
| | - Guillaume Bastille-Rousseau
- Cooperative Wildlife Research Laboratory, Southern Illinois University, Carbondale, Illinois, USA
- School of Biological Sciences, Southern Illinois University, Carbondale, Illinois, USA
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2
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Rosenblatt E, Cook JD, DiRenzo GV, Grant EHC, Arce F, Pepin KM, Rudolph FJ, Runge MC, Shriner S, Walsh DP, Mosher BA. Epidemiological modeling of SARS-CoV-2 in white-tailed deer (Odocoileus virginianus) reveals conditions for introduction and widespread transmission. PLoS Comput Biol 2024; 20:e1012263. [PMID: 38995977 PMCID: PMC11268674 DOI: 10.1371/journal.pcbi.1012263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 07/24/2024] [Accepted: 06/18/2024] [Indexed: 07/14/2024] Open
Abstract
Emerging infectious diseases with zoonotic potential often have complex socioecological dynamics and limited ecological data, requiring integration of epidemiological modeling with surveillance. Although our understanding of SARS-CoV-2 has advanced considerably since its detection in late 2019, the factors influencing its introduction and transmission in wildlife hosts, particularly white-tailed deer (Odocoileus virginianus), remain poorly understood. We use a Susceptible-Infected-Recovered-Susceptible epidemiological model to investigate the spillover risk and transmission dynamics of SARS-CoV-2 in wild and captive white-tailed deer populations across various simulated scenarios. We found that captive scenarios pose a higher risk of SARS-CoV-2 introduction from humans into deer herds and subsequent transmission among deer, compared to wild herds. However, even in wild herds, the transmission risk is often substantial enough to sustain infections. Furthermore, we demonstrate that the strength of introduction from humans influences outbreak characteristics only to a certain extent. Transmission among deer was frequently sufficient for widespread outbreaks in deer populations, regardless of the initial level of introduction. We also explore the potential for fence line interactions between captive and wild deer to elevate outbreak metrics in wild herds that have the lowest risk of introduction and sustained transmission. Our results indicate that SARS-CoV-2 could be introduced and maintained in deer herds across a range of circumstances based on testing a range of introduction and transmission risks in various captive and wild scenarios. Our approach and findings will aid One Health strategies that mitigate persistent SARS-CoV-2 outbreaks in white-tailed deer populations and potential spillback to humans.
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Affiliation(s)
- Elias Rosenblatt
- Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington, Vermont, United States of America
| | - Jonathan D. Cook
- U.S. Geological Survey, Eastern Ecological Science Center, Laurel, Maryland, United States of America
| | - Graziella V. DiRenzo
- U. S. Geological Survey, Massachusetts Cooperative Fish and Wildlife Research Unit, University of Massachusetts, Amherst, Massachusetts, United States of America
- Department of Environmental Conservation, University of Massachusetts, Amherst, Massachusetts, United States of America
| | - Evan H. Campbell Grant
- U.S. Geological Survey, Eastern Ecological Science Center, Turner’s Falls, Massachusetts, United States of America
| | - Fernando Arce
- Department of Environmental Conservation, University of Massachusetts, Amherst, Massachusetts, United States of America
| | - Kim M. Pepin
- National Wildlife Research Center, USDA, APHIS, Fort Collins, Colorado, United States of America
| | - F. Javiera Rudolph
- U.S. Geological Survey, Eastern Ecological Science Center, Laurel, Maryland, United States of America
- Department of Ecosystem Sciences and Management, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Michael C. Runge
- U.S. Geological Survey, Eastern Ecological Science Center, Laurel, Maryland, United States of America
| | - Susan Shriner
- National Wildlife Research Center, USDA, APHIS, Fort Collins, Colorado, United States of America
| | - Daniel P. Walsh
- U. S. Geological Survey, Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, Montana, United States of America
| | - Brittany A. Mosher
- Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington, Vermont, United States of America
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Strasburg M, Christensen S. Evaluating the Interaction of Emerging Diseases on White-Tailed Deer Populations Using an Agent-Based Modeling Approach. Pathogens 2024; 13:545. [PMID: 39057772 PMCID: PMC11279658 DOI: 10.3390/pathogens13070545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 06/04/2024] [Accepted: 06/21/2024] [Indexed: 07/28/2024] Open
Abstract
Disease co-occurrence in wildlife populations is common yet understudied. In the case of disease-caused mortality, the mortality attributed to one disease has the potential to buffer populations against subsequent alternative disease outbreaks by reducing populations and thus contacts needed to sustain disease transmission. However, substantial disease-driven population declines may also prevent populations from recovering, leading to localized extinctions. Hemorrhagic disease (HD), a vector-transmitted, viral disease in white-tailed deer (WTD), similar to chronic wasting disease (CWD), a prion disease, has increased in frequency and distribution in the United States. However, unlike CWD, which progresses slowly, HD can cause mortality only days after infection. Hemorrhagic disease outbreaks can result in substantial localized mortality events in WTD near vector habitats such as wetlands and may reduce local deer densities and consequent CWD transmission. The objective of our study was to evaluate the potential for HD outbreaks to buffer CWD risk where the diseases co-occur. Using an agent-based modeling approach, we found that frequent, intense HD outbreaks have the potential to mitigate CWD risk, especially if those outbreaks occur shortly after CWD introduction. However, HD outbreaks that do not result in substantial WTD mortality are unlikely to impact CWD or WTD population dynamics. Severe HD outbreaks may reduce CWD cases and could present an opportunity for managers to boost CWD control initiatives in a post-HD outbreak year.
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Affiliation(s)
| | - Sonja Christensen
- Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI 48824, USA;
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Carson BD, Orians CM, Crone EE. Caterpillar movement mediates spatially local interactions and determines the relationship between population density and contact. MOVEMENT ECOLOGY 2024; 12:34. [PMID: 38689374 PMCID: PMC11061915 DOI: 10.1186/s40462-024-00473-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 04/10/2024] [Indexed: 05/02/2024]
Abstract
BACKGROUND While interactions in nature are inherently local, ecological models often assume homogeneity across space, allowing for generalization across systems and greater mathematical tractability. Density-dependent disease models are a prominent example of models that assume homogeneous interactions, leading to the prediction that disease transmission will scale linearly with population density. In this study, we examined how the scale of larval butterfly movement interacts with the resource landscape to influence the relationship between larval contact and population density in the Baltimore checkerspot (Euphydryas phaeton). Our study was inspired by the recent discovery of a viral pathogen that is transmitted horizontally among Baltimore checkerspot larvae. METHODS We used multi-year larvae location data across six Baltimore checkerspot populations in the eastern U.S. to test whether larval nests are spatially clustered. We then integrated these spatial data with larval movement data in different resource contexts to investigate whether heterogeneity in spatially local interactions alters the assumed linear relationship between larval nest density and contact. We used Correlated Random Walk (CRW) models and field observations of larval movement behavior to construct Probability Distribution Functions (PDFs) of larval dispersal, and calculated the overlap in these PDFs to estimate conspecific contact within each population. RESULTS We found that all populations exhibited significant spatial clustering in their habitat use. Subsequent larval movement rates were influenced by encounters with host plants and larval age, and under many movement scenarios, the scale of predicted larval movement was not sufficient to allow for the "homogeneous mixing" assumed in density dependent disease models. Therefore, relationships between population density and larval contact were typically non-linear. We also found that observed use of available habitat patches led to significantly greater contact than would occur if habitat use were spatially random. CONCLUSIONS These findings strongly suggest that incorporating larval movement and spatial variation in larval interactions is critical to modeling disease outcomes in E. phaeton. Epidemiological models that assume a linear relationship between population density and larval contact have the potential to underestimate transmission rates, especially in small populations that are already vulnerable to extinction.
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Affiliation(s)
- Brendan D Carson
- Department of Biology, Tufts University, Medford, MA, 02155, USA.
| | - Colin M Orians
- Department of Biology, Tufts University, Medford, MA, 02155, USA
| | - Elizabeth E Crone
- Department of Biology, Tufts University, Medford, MA, 02155, USA
- Department of Evolution and Ecology, University of California, Davis, CA, 95616, USA
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5
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Yang A, Boughton R, Miller RS, Snow NP, Vercauteren KC, Pepin KM, Wittemyer G. Individual-level patterns of resource selection do not predict hotspots of contact. MOVEMENT ECOLOGY 2023; 11:74. [PMID: 38037089 PMCID: PMC10687890 DOI: 10.1186/s40462-023-00435-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 11/08/2023] [Indexed: 12/02/2023]
Abstract
Contact among animals is crucial for various ecological processes, including social behaviors, disease transmission, and predator-prey interactions. However, the distribution of contact events across time and space is heterogeneous, influenced by environmental factors and biological purposes. Previous studies have assumed that areas with abundant resources and preferred habitats attract more individuals and, therefore, lead to more contact. To examine the accuracy of this assumption, we used a use-available framework to compare landscape factors influencing the location of contacts between wild pigs (Sus scrofa) in two study areas in Florida and Texas (USA) from those influencing non-contact space use. We employed a contact-resource selection function (RSF) model, where contact locations were defined as used points and locations without contact as available points. By comparing outputs from this contact RSF with a general, population-level RSF, we assessed the factors driving both habitat selection and contact. We found that the landscape predictors (e.g., wetland, linear features, and food resources) played different roles in habitat selection from contact processes for wild pigs in both study areas. This indicated that pigs interacted with their landscapes differently when choosing habitats compared to when they encountered other individuals. Consequently, relying solely on the spatial overlap of individual or population-level RSF models may lead to a misleading understanding of contact-related ecology. Our findings challenge prevailing assumptions about contact and introduce innovative approaches to better understand the ecological drivers of spatially explicit contact. By accurately predicting the spatial distribution of contact events, we can enhance our understanding of contact based ecological processes and their spatial dynamics.
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Affiliation(s)
- Anni Yang
- Department of Geography and Environmental Sustainability, University of Oklahoma, Norman, OK, 73019, USA.
| | - Raoul Boughton
- Archbold Biological Station, Buck Island Ranch, Lake Placid, FL, 33852, USA
| | - Ryan S Miller
- United States Department of Agriculture, Animal and Plant Health Inspection Service, Veterinary Service, Center for Epidemiology and Animal Health, 2150 Centre Avenue, Fort Collins, CO, 80526, USA
| | - Nathan P Snow
- United States Department of Agriculture, Animal and Plant Health Inspection Service, National Wildlife Research Center, Wildlife Services, Fort Collins, CO, 80521, USA
| | - Kurt C Vercauteren
- United States Department of Agriculture, Animal and Plant Health Inspection Service, National Wildlife Research Center, Wildlife Services, Fort Collins, CO, 80521, USA
| | - Kim M Pepin
- United States Department of Agriculture, Animal and Plant Health Inspection Service, National Wildlife Research Center, Wildlife Services, Fort Collins, CO, 80521, USA
| | - George Wittemyer
- Department of Fish, Wildlife and Conservation Biology, Colorado State University, Fort Collins, CO, 80523, USA
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6
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Clement MJ, Justice-Allen A, Heale JD. Optimal risk-based allocation of disease surveillance effort for clustered disease outbreaks. Prev Vet Med 2023; 212:105830. [PMID: 36657356 DOI: 10.1016/j.prevetmed.2022.105830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 12/19/2022] [Accepted: 12/22/2022] [Indexed: 01/07/2023]
Abstract
Designing a disease surveillance program to detect a disease is challenging when animals are organized into herds, in part because disease cases are likely to be clustered. Clustered diseases are often surveilled using two-stage sampling, which allocates tests both among herds and within herds. Finding the optimal allocation of tests is computationally difficult, so some surveillance programs simply seek an approximate solution. We developed a search algorithm to find the optimal allocation of tests by iteratively searching for adjustments to the test allocation that yielded marginal improvements in system sensitivity. We digitally generated 21 herds of various sizes, evenly divided among three regions that differed in relative risk. We then analyzed 29 scenarios that differed in disease and testing characteristics. We also analyzed a Chronic Wasting Disease (CWD) surveillance effort for 23 elk game management units of various sizes that were spread across three regions in Arizona, USA. We compared our marginal sensitivity approach to two other strategies for approximating the optimal distribution of tests: allocating the same number of tests to all herds selected for testing, and allocating tests so that all herds selected for testing achieve the same sensitivity. Across analysis scenarios, we found that low prevalence, high relative risk, a small budget, or high overhead costs were best addressed by concentrating tests in large, high-risk herds. When we expect multiple herds to be infected, the optimal allocation of tests depended on how we expected the cases to be distributed. Across the analyzed scenarios, our marginal sensitivity approach was most efficient, with alternative strategies requiring 0-228 % more tests to achieve the same sensitivity. For CWD in Arizona, we found the potential to double system sensitivity, given a population design prevalence of 0.16 %, from 35.8 % to 70.5 %, although social and budgetary considerations would likely constrain changes to the current allocation of tests. The marginal sensitivity approach we developed has the potential to improve disease surveillance, especially when a population includes a limited number of herds that differ in size. An important limitation of our approach is that computer runtimes could become unacceptably long for a population with many herds.
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Affiliation(s)
- Matthew J Clement
- Arizona Game and Fish Department, 5000 W. Carefree Highway, Phoenix, AZ 85086, USA.
| | - Anne Justice-Allen
- Arizona Game and Fish Department, 5000 W. Carefree Highway, Phoenix, AZ 85086, USA
| | - Jonathon D Heale
- Arizona Game and Fish Department, 5000 W. Carefree Highway, Phoenix, AZ 85086, USA
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7
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Impact of landcover composition and density of localized deer culling sites on chronic wasting disease prevalence. Prev Vet Med 2022; 208:105774. [DOI: 10.1016/j.prevetmed.2022.105774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 09/20/2022] [Accepted: 10/02/2022] [Indexed: 11/30/2022]
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8
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Spreading speed of chronic wasting disease across deer groups with overlapping home ranges. J Theor Biol 2022; 547:111135. [DOI: 10.1016/j.jtbi.2022.111135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 04/13/2022] [Accepted: 04/17/2022] [Indexed: 11/20/2022]
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9
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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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10
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Pepin KM, Golnar A, Podgórski T. Social structure defines spatial transmission of African swine fever in wild boar. J R Soc Interface 2021; 18:20200761. [PMID: 33468025 DOI: 10.1098/rsif.2020.0761] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The spatial spread of infectious disease is determined by spatial and social processes such as animal space use and family group structure. Yet, the impacts of social processes on spatial spread remain poorly understood and estimates of spatial transmission kernels (STKs) often exclude social structure. Understanding the impacts of social structure on STKs is important for obtaining robust inferences for policy decisions and optimizing response plans. We fit spatially explicit transmission models with different assumptions about contact structure to African swine fever virus surveillance data from eastern Poland from 2014 to 2015 and evaluated how social structure affected inference of STKs and spatial spread. The model with social structure provided better inference of spatial spread, predicted that approximately 80% of transmission events occurred within family groups, and that transmission was weakly female-biased (other models predicted weakly male-biased transmission). In all models, most transmission events were within 1.5 km, with some rare events at longer distances. Effective reproductive numbers were between 1.1 and 2.5 (maximum values between 4 and 8). Social structure can modify spatial transmission dynamics. Accounting for this additional contact heterogeneity in spatial transmission models could provide more robust inferences of STKs for policy decisions, identify best control targets and improve transparency in model uncertainty.
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Affiliation(s)
- Kim M Pepin
- National Wildlife Research Center, USDA, APHIS, Wildlife Services, 4101 Laporte Avenue, Fort Collins, CO 80526, USA
| | - Andrew Golnar
- National Wildlife Research Center, USDA, APHIS, Wildlife Services, 4101 Laporte Avenue, Fort Collins, CO 80526, USA
| | - Tomasz Podgórski
- Mammal Research Institute, Polish Academy of Sciences, Stoczek 1, 17-230 Białowieża, Poland.,Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Kamýcká 129, 165 00 Praha 6, Czech Republic
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11
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Escobar LE, Pritzkow S, Winter SN, Grear DA, Kirchgessner MS, Dominguez-Villegas E, Machado G, Peterson AT, Soto C. The ecology of chronic wasting disease in wildlife. Biol Rev Camb Philos Soc 2020; 95:393-408. [PMID: 31750623 PMCID: PMC7085120 DOI: 10.1111/brv.12568] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 10/11/2019] [Accepted: 10/16/2019] [Indexed: 12/13/2022]
Abstract
Prions are misfolded infectious proteins responsible for a group of fatal neurodegenerative diseases termed transmissible spongiform encephalopathy or prion diseases. Chronic Wasting Disease (CWD) is the prion disease with the highest spillover potential, affecting at least seven Cervidae (deer) species. The zoonotic potential of CWD is inconclusive and cannot be ruled out. A risk of infection for other domestic and wildlife species is also plausible. Here, we review the current status of the knowledge with respect to CWD ecology in wildlife. Our current understanding of the geographic distribution of CWD lacks spatial and temporal detail, does not consider the biogeography of infectious diseases, and is largely biased by sampling based on hunters' cooperation and funding available for each region. Limitations of the methods used for data collection suggest that the extent and prevalence of CWD in wildlife is underestimated. If the zoonotic potential of CWD is confirmed in the short term, as suggested by recent results obtained in experimental animal models, there will be limited accurate epidemiological data to inform public health. Research gaps in CWD prion ecology include the need to identify specific biological characteristics of potential CWD reservoir species that better explain susceptibility to spillover, landscape and climate configurations that are suitable for CWD transmission, and the magnitude of sampling bias in our current understanding of CWD distribution and risk. Addressing these research gaps will help anticipate novel areas and species where CWD spillover is expected, which will inform control strategies. From an ecological perspective, control strategies could include assessing restoration of natural predators of CWD reservoirs, ultrasensitive CWD detection in biotic and abiotic reservoirs, and deer density and landscape modification to reduce CWD spread and prevalence.
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Affiliation(s)
- Luis E. Escobar
- Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA, 24061, U.S.A
| | - Sandra Pritzkow
- Mitchell Center for Alzheimer’s Disease and Related Brain Disorders, Department of Neurology, University of Texas Medical School at Houston, Houston, TX, 77030, U.S.A
| | - Steven N. Winter
- Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA, 24061, U.S.A
| | - Daniel A. Grear
- US Geological Survey National Wildlife Health Center, Madison, WI, 59711, U.S.A
| | | | | | - Gustavo Machado
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, 27606, U.S.A
| | - A. Townsend Peterson
- Biodiversity Institute and Department of Ecology and Evolutionary Biology, The University of Kansas, Lawrence, KS, 66045, U.S.A
| | - Claudio Soto
- Mitchell Center for Alzheimer’s Disease and Related Brain Disorders, Department of Neurology, University of Texas Medical School at Houston, Houston, TX, 77030, U.S.A
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12
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Malagon DA, Melara LA, Prosper OF, Lenhart S, Carter ED, Fordyce JA, Peterson AC, Miller DL, Gray MJ. Host density and habitat structure influence host contact rates and Batrachochytrium salamandrivorans transmission. Sci Rep 2020; 10:5584. [PMID: 32221329 PMCID: PMC7101388 DOI: 10.1038/s41598-020-62351-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 03/11/2020] [Indexed: 12/22/2022] Open
Abstract
Batrachochytrium salamandrivorans (Bsal) is an emerging invasive pathogen that is highly pathogenic to salamander species. Modeling infection dynamics in this system can facilitate proactive efforts to mitigate this pathogen's impact on North American species. Given its widespread distribution and high abundance, the eastern newt (Notophthalmus viridescens) has the potential to significantly influence Bsal epidemiology. We designed experiments to 1) estimate contact rates given different host densities and habitat structure and 2) estimate the probability of transmission from infected to susceptible individuals. Using parameter estimates from data generated during these experiments, we modeled infection and disease outcomes for a population of newts using a system of differential equations. We found that host contact rates were density-dependent, and that adding habitat structure reduced contacts. The probability of Bsal transmission given contact between newts was very high (>90%) even at early stages of infection. Our simulations show rapid transmission of Bsal among individuals following pathogen introduction, with infection prevalence exceeding 90% within one month and >80% mortality of newts in three months. Estimates of basic reproductive rate (R0) of Bsal for eastern newts were 1.9 and 3.2 for complex and simple habitats, respectively. Although reducing host density and increasing habitat complexity might decrease transmission, these management strategies may be ineffective at stopping Bsal invasion in eastern newt populations due to this species’ hyper-susceptibility.
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Affiliation(s)
- Daniel A Malagon
- Center for Wildlife Health, Department of Forestry, Wildlife and Fisheries, University of Tennessee Institute of Agriculture, Knoxville, TN, 37996, USA
| | - Luis A Melara
- Department of Mathematics, Shippensburg University, Shippensburg, PA, 17257, USA
| | - Olivia F Prosper
- Department of Mathematics, University of Kentucky, Lexington, KY, 40506, USA.,Department of Mathematics, University of Tennessee, Knoxville, TN, 37996, USA
| | - Suzanne Lenhart
- Department of Mathematics, University of Tennessee, Knoxville, TN, 37996, USA
| | - Edward Davis Carter
- Center for Wildlife Health, Department of Forestry, Wildlife and Fisheries, University of Tennessee Institute of Agriculture, Knoxville, TN, 37996, USA
| | - J A Fordyce
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | - Anna C Peterson
- Center for Wildlife Health, Department of Forestry, Wildlife and Fisheries, University of Tennessee Institute of Agriculture, Knoxville, TN, 37996, USA
| | - Debra L Miller
- Center for Wildlife Health, Department of Forestry, Wildlife and Fisheries, University of Tennessee Institute of Agriculture, Knoxville, TN, 37996, USA.,Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN, 37996, USA
| | - Matthew J Gray
- Center for Wildlife Health, Department of Forestry, Wildlife and Fisheries, University of Tennessee Institute of Agriculture, Knoxville, TN, 37996, USA.
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13
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Koutsoumanis K, Allende A, Alvarez-Ordoňez A, Bolton D, Bover-Cid S, Chemaly M, Davies R, De Cesare A, Herman L, Hilbert F, Lindqvist R, Nauta M, Peixe L, Ru G, Skandamis P, Suffredini E, Andreoletti O, Benestad SL, Comoy E, Nonno R, da Silva Felicio T, Ortiz-Pelaez A, Simmons MM. Update on chronic wasting disease (CWD) III. EFSA J 2019; 17:e05863. [PMID: 32626163 PMCID: PMC7008890 DOI: 10.2903/j.efsa.2019.5863] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The European Commission asked EFSA for a Scientific Opinion: to revise the state of knowledge about the differences between the chronic wasting disease (CWD) strains found in North America (NA) and Europe and within Europe; to review new scientific evidence on the zoonotic potential of CWD and to provide recommendations to address the potential risks and to identify risk factors for the spread of CWD in the European Union. Full characterisation of European isolates is being pursued, whereas most NA CWD isolates have not been characterised in this way. The differing surveillance programmes in these continents result in biases in the types of cases that can be detected. Preliminary data support the contention that the CWD strains identified in Europe and NA are different and suggest the presence of strain diversity in European cervids. Current data do not allow any conclusion on the implications of strain diversity on transmissibility, pathogenesis or prevalence. Available data do not allow any conclusion on the zoonotic potential of NA or European CWD isolates. The risk of CWD to humans through consumption of meat cannot be directly assessed. At individual level, consumers of meat, meat products and offal derived from CWD-infected cervids will be exposed to the CWD agent(s). Measures to reduce human dietary exposure could be applied, but exclusion from the food chain of whole carcasses of infected animals would be required to eliminate exposure. Based on NA experiences, all the risk factors identified for the spread of CWD may be associated with animals accumulating infectivity in both the peripheral tissues and the central nervous system. A subset of risk factors is relevant for infected animals without involvement of peripheral tissues. All the risk factors should be taken into account due to the potential co-localisation of animals presenting with different disease phenotypes.
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14
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Podgórski T, Borowik T, Łyjak M, Woźniakowski G. Spatial epidemiology of African swine fever: Host, landscape and anthropogenic drivers of disease occurrence in wild boar. Prev Vet Med 2019; 177:104691. [PMID: 31122672 DOI: 10.1016/j.prevetmed.2019.104691] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 04/29/2019] [Accepted: 05/15/2019] [Indexed: 11/27/2022]
Abstract
Host abundance and landscape structure often interact to shape spatial patterns of many wildlife diseases. Emergence, spread, and persistence of African swine fever (ASF) among wild boar in eastern Europe has raised questions on the factors underlying ASF dynamics in this novel host-pathogen system. This work identifies drivers of ASF occurrence in natural wild boar population. We evaluated factors shaping the probability of ASF-postitive wild boar during the first three years (2014-2016) of the ASF epidemic in Poland. We expected to observe positive effects of wild boar density, proportion of forested area, human activity, and proximity to previous infections on ASF case probability. We tested these predictions using the infection status of 830 wild boar samples and generalized mixed-effects models. The probability of ASF case increased from 3 to 20% as population density rose from 0.4 to 2 ind./km2. The positive effect of population density on ASF case probability was stronger at locations near previous ASF incidents. ASF was more likely to occur in forested areas, with the probability of detecting an ASF positive sample rising from 2 to 11% as forest cover around the sample increased from 0.5 to 100%. This pattern was consistent at both low and high wild boar densities. Indicators of human activity were poor predictors of ASF occurrence. Disease control efforts, such as culling and carcass search, should be focused on high-density populations where chances of detecting and eliminating ASF-positive wild boar are higher. The intensity of control measures should decrease with distance from the infected area to match the observed spatial pattern of ASF case probability. Woodlands represent areas of the highest risk of ASF case occurrence. Distribution and connectivity of suitable habitats over the landscape can be used to prioritize disease-management actions.
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Affiliation(s)
- Tomasz Podgórski
- Mammal Research Institute, Polish Academy of Sciences, Białowieża, Poland; Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Praha, Czech Republic.
| | - Tomasz Borowik
- Mammal Research Institute, Polish Academy of Sciences, Białowieża, Poland
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15
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Development of a Novel Mule Deer Genomic Assembly and Species-Diagnostic SNP Panel for Assessing Introgression in Mule Deer, White-Tailed Deer, and Their Interspecific Hybrids. G3-GENES GENOMES GENETICS 2019; 9:911-919. [PMID: 30670611 PMCID: PMC6404596 DOI: 10.1534/g3.118.200838] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Mule deer (Odocoileus hemionus) are endemic to a wide variety of habitats in western North America, many of which are shared in sympatry with their closely related sister-species white-tailed deer (Odocoileus virginianus), whom they hybridize with in wild populations. Although mule deer meet many ideal conditions for a molecular ecological research species, such as high abundance, ecological importance, and broad dispersal and gene flow, conservation genetic studies have been limited by a relative lack of existing genomic resources and inherent difficulties caused by introgression with white-tailed deer. Many molecular tools currently available for the study of cervids were designed using reference assemblies of divergent model species, specifically cattle (Bos taurus). Bovidae and Cervidae diverged approximately 28 million years ago, therefore, we sought to ameliorate the available resources by contributing the first mule deer whole genome sequence draft assembly with an average genome-wide read depth of 25X, using the white-tailed genome assembly (Ovir.te_1.0) as a reference. Comparing the two assemblies, we identified ∼33 million single nucleotide polymorphisms (SNPs) and insertion/deletion variants. We then verified fixed SNP differences between the two species and developed a 40-loci SNP assay capable of identifying pure mule deer, white-tailed deer, and interspecific hybrids. Assignment capacity of the panel, which was tested on simulated datasets, is reliable up to and including the third backcross hybrid generation. Identification of post-F1 hybrids will be necessary for hybrid zone population studies going forward, and the new mule deer assembly will be a valuable resource for genetic and comparative genomics studies.
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16
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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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17
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Huyvaert KP, Russell RE, Patyk KA, Craft ME, Cross PC, Garner MG, Martin MK, Nol P, Walsh DP. Challenges and Opportunities Developing Mathematical Models of Shared Pathogens of Domestic and Wild Animals. Vet Sci 2018; 5:E92. [PMID: 30380736 PMCID: PMC6313884 DOI: 10.3390/vetsci5040092] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 10/04/2018] [Accepted: 10/18/2018] [Indexed: 01/19/2023] Open
Abstract
Diseases that affect both wild and domestic animals can be particularly difficult to prevent, predict, mitigate, and control. Such multi-host diseases can have devastating economic impacts on domestic animal producers and can present significant challenges to wildlife populations, particularly for populations of conservation concern. Few mathematical models exist that capture the complexities of these multi-host pathogens, yet the development of such models would allow us to estimate and compare the potential effectiveness of management actions for mitigating or suppressing disease in wildlife and/or livestock host populations. We conducted a workshop in March 2014 to identify the challenges associated with developing models of pathogen transmission across the wildlife-livestock interface. The development of mathematical models of pathogen transmission at this interface is hampered by the difficulties associated with describing the host-pathogen systems, including: (1) the identity of wildlife hosts, their distributions, and movement patterns; (2) the pathogen transmission pathways between wildlife and domestic animals; (3) the effects of the disease and concomitant mitigation efforts on wild and domestic animal populations; and (4) barriers to communication between sectors. To promote the development of mathematical models of transmission at this interface, we recommend further integration of modern quantitative techniques and improvement of communication among wildlife biologists, mathematical modelers, veterinary medicine professionals, producers, and other stakeholders concerned with the consequences of pathogen transmission at this important, yet poorly understood, interface.
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Affiliation(s)
- Kathryn P Huyvaert
- Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, CO 80523, USA.
| | - Robin E Russell
- U.S. Geological Survey, National Wildlife Health Center, Madison, WI 53711, USA.
| | - Kelly A Patyk
- Center for Epidemiology and Animal Health, United States Department of Agriculture, Animal and Plant Health Inspection Service, Fort Collins, CO 80526, USA.
| | - Meggan E Craft
- Department of Veterinary Population Medicine, University of Minnesota, St. Paul, MN 55108, USA.
| | - Paul C Cross
- U.S. Geological Survey, Northern Rocky Mountain Science Center, Bozeman, MT 59715, USA.
| | - M Graeme Garner
- European Commission for the Control of Foot-and-Mouth Disease-Food and Agriculture Organization of the United Nations, 00153 Roma RM, Italy.
| | - Michael K Martin
- Livestock Poultry Health Division, Clemson University, Columbia, SC 29224, USA.
| | - Pauline Nol
- Center for Epidemiology and Animal Health, United States Department of Agriculture, Animal and Plant Health Inspection Service, Fort Collins, CO 80526, USA.
| | - Daniel P Walsh
- U.S. Geological Survey, National Wildlife Health Center, Madison, WI 53711, USA.
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18
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Tardy O, Massé A, Pelletier F, Fortin D. Interplay between contact risk, conspecific density, and landscape connectivity: An individual-based modeling framework. Ecol Modell 2018. [DOI: 10.1016/j.ecolmodel.2018.02.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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19
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Mejía‐Salazar MF, Waldner CL, Hwang YT, Bollinger TK. Use of environmental sites by mule deer: a proxy for relative risk of chronic wasting disease exposure and transmission. Ecosphere 2018. [DOI: 10.1002/ecs2.2055] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Affiliation(s)
- María Fernanda Mejía‐Salazar
- Department of Veterinary Pathology University of Saskatchewan 52 Campus Drive Saskatoon Saskatchewan S7N 5B4 Canada
| | - Cheryl L. Waldner
- Department of Large Animal Clinical Sciences University of Saskatchewan 52 Campus Drive Saskatoon Saskatchewan S7N 5B4 Canada
| | - Yeen Ten Hwang
- Department of Veterinary Pathology University of Saskatchewan 52 Campus Drive Saskatoon Saskatchewan S7N 5B4 Canada
- Fish and Wildlife Branch Saskatchewan Ministry of Environment Regina Saskatchewan S4S 5W6 Canada
| | - Trent K. Bollinger
- Department of Veterinary Pathology University of Saskatchewan 52 Campus Drive Saskatoon Saskatchewan S7N 5B4 Canada
- Canadian Wildlife Health Cooperative (CWHC) 52 Campus Drive Saskatoon Saskatchewan S7N 5B4 Canada
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20
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Dorak SJ, Green ML, Wander MM, Ruiz MO, Buhnerkempe MG, Tian T, Novakofski JE, Mateus-Pinilla NE. Clay content and pH: soil characteristic associations with the persistent presence of chronic wasting disease in northern Illinois. Sci Rep 2017; 7:18062. [PMID: 29273783 PMCID: PMC5741720 DOI: 10.1038/s41598-017-18321-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 12/08/2017] [Indexed: 01/13/2023] Open
Abstract
Environmental reservoirs are important to infectious disease transmission and persistence, but empirical analyses are relatively few. The natural environment is a reservoir for prions that cause chronic wasting disease (CWD) and influences the risk of transmission to susceptible cervids. Soil is one environmental component demonstrated to affect prion infectivity and persistence. Here we provide the first landscape predictive model for CWD based solely on soil characteristics. We built a boosted regression tree model to predict the probability of the persistent presence of CWD in a region of northern Illinois using CWD surveillance in deer and soils data. We evaluated the outcome for possible pathways by which soil characteristics may increase the probability of CWD transmission via environmental contamination. Soil clay content and pH were the most important predictive soil characteristics of the persistent presence of CWD. The results suggest that exposure to prions in the environment is greater where percent clay is less than 18% and soil pH is greater than 6.6. These characteristics could alter availability of prions immobilized in soil and contribute to the environmental risk factors involved in the epidemiological complexity of CWD infection in natural populations of white-tailed deer.
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Affiliation(s)
- Sheena J Dorak
- Illinois Natural History Survey - Prairie Research Institute, University of Illinois Urbana-Champaign, 1816 S Oak Street, Champaign, IL, 61820, USA
| | - Michelle L Green
- Illinois Natural History Survey - Prairie Research Institute, University of Illinois Urbana-Champaign, 1816 S Oak Street, Champaign, IL, 61820, USA.,Department of Animal Sciences, University of Illinois Urbana-Champaign, 1503 S Maryland Drive, Urbana, IL, 61801, USA
| | - Michelle M Wander
- Department of Natural Resources and Environmental Sciences, University of Illinois Urbana-Champaign, 1102 S Goodwin Ave, Urbana, IL, 61801, USA
| | - Marilyn O Ruiz
- Department of Pathobiology, University of Illinois Urbana-Champaign, 2001 S Lincoln Avenue, Urbana, IL, 61802, USA
| | - Michael G Buhnerkempe
- Illinois Natural History Survey - Prairie Research Institute, University of Illinois Urbana-Champaign, 1816 S Oak Street, Champaign, IL, 61820, USA
| | - Ting Tian
- Illinois Natural History Survey - Prairie Research Institute, University of Illinois Urbana-Champaign, 1816 S Oak Street, Champaign, IL, 61820, USA
| | - Jan E Novakofski
- Department of Animal Sciences, University of Illinois Urbana-Champaign, 1503 S Maryland Drive, Urbana, IL, 61801, USA
| | - Nohra E Mateus-Pinilla
- Illinois Natural History Survey - Prairie Research Institute, University of Illinois Urbana-Champaign, 1816 S Oak Street, Champaign, IL, 61820, USA.
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21
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White LA, Forester JD, Craft ME. Dynamic, spatial models of parasite transmission in wildlife: Their structure, applications and remaining challenges. J Anim Ecol 2017; 87:559-580. [PMID: 28944450 DOI: 10.1111/1365-2656.12761] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Accepted: 09/07/2017] [Indexed: 01/26/2023]
Abstract
Individual differences in contact rate can arise from host, group and landscape heterogeneity and can result in different patterns of spatial spread for diseases in wildlife populations with concomitant implications for disease control in wildlife of conservation concern, livestock and humans. While dynamic disease models can provide a better understanding of the drivers of spatial spread, the effects of landscape heterogeneity have only been modelled in a few well-studied wildlife systems such as rabies and bovine tuberculosis. Such spatial models tend to be either purely theoretical with intrinsic limiting assumptions or individual-based models that are often highly species- and system-specific, limiting the breadth of their utility. Our goal was to review studies that have utilized dynamic, spatial models to answer questions about pathogen transmission in wildlife and identify key gaps in the literature. We begin by providing an overview of the main types of dynamic, spatial models (e.g., metapopulation, network, lattice, cellular automata, individual-based and continuous-space) and their relation to each other. We investigate different types of ecological questions that these models have been used to explore: pathogen invasion dynamics and range expansion, spatial heterogeneity and pathogen persistence, the implications of management and intervention strategies and the role of evolution in host-pathogen dynamics. We reviewed 168 studies that consider pathogen transmission in free-ranging wildlife and classify them by the model type employed, the focal host-pathogen system, and their overall research themes and motivation. We observed a significant focus on mammalian hosts, a few well-studied or purely theoretical pathogen systems, and a lack of studies occurring at the wildlife-public health or wildlife-livestock interfaces. Finally, we discuss challenges and future directions in the context of unprecedented human-mediated environmental change. Spatial models may provide new insights into understanding, for example, how global warming and habitat disturbance contribute to disease maintenance and emergence. Moving forward, better integration of dynamic, spatial disease models with approaches from movement ecology, landscape genetics/genomics and ecoimmunology may provide new avenues for investigation and aid in the control of zoonotic and emerging infectious diseases.
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Affiliation(s)
- Lauren A White
- Department of Ecology, Evolution & Behavior, University of Minnesota, St. Paul, MN, USA
| | - James D Forester
- Department of Fisheries, Wildlife, and Conservation Biology, University of Minnesota, St. Paul, MN, USA
| | - Meggan E Craft
- Department of Veterinary Population Medicine, University of Minnesota, St. Paul, MN, USA
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22
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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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23
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Koen EL, Tosa MI, Nielsen CK, Schauber EM. Does landscape connectivity shape local and global social network structure in white-tailed deer? PLoS One 2017; 12:e0173570. [PMID: 28306748 PMCID: PMC5357016 DOI: 10.1371/journal.pone.0173570] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2016] [Accepted: 02/23/2017] [Indexed: 12/03/2022] Open
Abstract
Intraspecific social behavior can be influenced by both intrinsic and extrinsic factors. While much research has focused on how characteristics of individuals influence their roles in social networks, we were interested in the role that landscape structure plays in animal sociality at both individual (local) and population (global) levels. We used female white-tailed deer (Odocoileus virginianus) in Illinois, USA, to investigate the potential effect of landscape on social network structure by weighting the edges of seasonal social networks with association rate (based on proximity inferred from GPS collar data). At the local level, we found that sociality among female deer in neighboring social groups (n = 36) was mainly explained by their home range overlap, with two exceptions: 1) during fawning in an area of mixed forest and grassland, deer whose home ranges had low forest connectivity were more social than expected; and 2) during the rut in an area of intensive agriculture, deer inhabiting home ranges with high amount and connectedness of agriculture were more social than expected. At the global scale, we found that deer populations (n = 7) in areas with highly connected forest-agriculture edge, a high proportion of agriculture, and a low proportion of forest tended to have higher weighted network closeness, although low sample size precluded statistical significance. This result implies that infectious disease could spread faster in deer populations inhabiting such landscapes. Our work advances the general understanding of animal social networks, demonstrating how landscape features can underlie differences in social behavior both within and among wildlife social networks.
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Affiliation(s)
- Erin L. Koen
- Cooperative Wildlife Research Laboratory, Southern Illinois University, Carbondale, Illinois, United States of America
- * E-mail:
| | - Marie I. Tosa
- Cooperative Wildlife Research Laboratory, Southern Illinois University, Carbondale, Illinois, United States of America
- Department of Zoology and Center for Ecology, Southern Illinois University, Carbondale, Illinois, United States of America
| | - Clayton K. Nielsen
- Cooperative Wildlife Research Laboratory, Southern Illinois University, Carbondale, Illinois, United States of America
- Department of Forestry, Southern Illinois University, Carbondale, Illinois, United States of America
| | - Eric M. Schauber
- Cooperative Wildlife Research Laboratory, Southern Illinois University, Carbondale, Illinois, United States of America
- Department of Zoology and Center for Ecology, Southern Illinois University, Carbondale, Illinois, United States of America
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24
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Ricci A, Allende A, Bolton D, Chemaly M, Davies R, Fernández Escámez PS, Gironés R, Herman L, Koutsoumanis K, Lindqvist R, Nørrung B, Robertson L, Sanaa M, Skandamis P, Snary E, Speybroeck N, Ter Kuile B, Threlfall J, Wahlström H, Benestad S, Gavier-Widen D, Miller MW, Ru G, Telling GC, Tryland M, Ortiz Pelaez A, Simmons M. Chronic wasting disease (CWD) in cervids. EFSA J 2017; 15:e04667. [PMID: 32625260 PMCID: PMC7010154 DOI: 10.2903/j.efsa.2017.4667] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
In April and May of 2016, Norway confirmed two cases of chronic wasting disease (CWD) in a wild reindeer and a wild moose, respectively. In the light of this emerging issue, the European Commission requested EFSA to recommend surveillance activities and, if necessary, additional animal health risk-based measures to prevent the introduction of the disease and the spread into/within the EU, specifically Estonia, Finland, Iceland, Latvia, Lithuania, Norway, Poland and Sweden, and considering seven wild, semidomesticated and farmed cervid species (Eurasian tundra reindeer, Finnish (Eurasian) forest reindeer, moose, roe deer, white-tailed deer, red deer and fallow deer). It was also asked to assess any new evidence on possible public health risks related to CWD. A 3-year surveillance system is proposed, differing for farmed and wild or semidomesticated cervids, with a two-stage sampling programme at the farm/geographically based population unit level (random sampling) and individual level (convenience sampling targeting high-risk animals). The current derogations of Commission Implementing Decision (EU) 2016/1918 present a risk of introduction of CWD into the EU. Measures to prevent the spread of CWD within the EU are dependent upon the assumption that the disease is already present; this is currently unknown. The measures listed are intended to contain (limit the geographic extent of a focus) and/or to control (actively stabilise/reduce infection rates in an affected herd or population) the disease where it occurs. With regard to the zoonotic potential, the human species barrier for CWD prions does not appear to be absolute. These prions are present in the skeletal muscle and other edible tissues, so humans may consume infected material in enzootic areas. Epidemiological investigations carried out to date make no association between the occurrence of sporadic Creutzfeldt-Jakob disease in humans and exposure to CWD prions.
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25
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Modeled Impacts of Chronic Wasting Disease on White-Tailed Deer in a Semi-Arid Environment. PLoS One 2016; 11:e0163592. [PMID: 27711208 PMCID: PMC5053495 DOI: 10.1371/journal.pone.0163592] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 09/12/2016] [Indexed: 12/21/2022] Open
Abstract
White-tailed deer are a culturally and economically important game species in North America, especially in South Texas. The recent discovery of chronic wasting disease (CWD) in captive deer facilities in Texas has increased concern about the potential emergence of CWD in free-ranging deer. The concern is exacerbated because much of the South Texas region is a semi-arid environment with variable rainfall, where precipitation is strongly correlated with fawn recruitment. Further, the marginally productive rangelands, in combination with erratic fawn recruitment, results in populations that are frequently density-independent, and thus sensitive to additive mortality. It is unknown how a deer population in semi-arid regions would respond to the presence of CWD. We used long-term empirical datasets from a lightly harvested (2% annual harvest) population in conjunction with 3 prevalence growth rates from CWD afflicted areas (0.26%, 0.83%, and 2.3% increases per year) via a multi-stage partially deterministic model to simulate a deer population for 25 years under four scenarios: 1) without CWD and without harvest, 2) with CWD and without harvest, 3) with CWD and male harvest only, and 4) with CWD and harvest of both sexes. The modeled populations without CWD and without harvest averaged a 1.43% annual increase over 25 years; incorporation of 2% annual harvest of both sexes resulted in a stable population. The model with slowest CWD prevalence rate growth (0.26% annually) without harvest resulted in stable populations but the addition of 1% harvest resulted in population declines. Further, the male age structure in CWD models became skewed to younger age classes. We incorporated fawn:doe ratios from three CWD afflicted areas in Wisconsin and Wyoming into the model with 0.26% annual increase in prevalence and populations did not begin to decline until ~10%, ~16%, and ~26% of deer were harvested annually. Deer populations in variable environments rely on high adult survivorship to buffer the low and erratic fawn recruitment rates. The increase in additive mortality rates for adults via CWD negatively impacted simulated population trends to the extent that hunter opportunity would be greatly reduced. Our results improve understanding of the potential influences of CWD on deer populations in semi-arid environments with implications for deer managers, disease ecologists, and policy makers.
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26
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Nobert BR, Merrill EH, Pybus MJ, Bollinger TK, Hwang YT. Landscape connectivity predicts chronic wasting disease risk in Canada. J Appl Ecol 2016. [DOI: 10.1111/1365-2664.12677] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Barry R. Nobert
- Department of Biological Sciences; University of Alberta; Edmonton AB T6G 2E9 Canada
| | - Evelyn H. Merrill
- Department of Biological Sciences; University of Alberta; Edmonton AB T6G 2E9 Canada
| | - Margo J. Pybus
- Department of Biological Sciences; University of Alberta; Edmonton AB T6G 2E9 Canada
- Alberta Fish and Wildlife Division; Government of Alberta; Edmonton AB T6H 4P2 Canada
| | - Trent K. Bollinger
- Canadian Cooperative Wildlife Health Centre; Western College of Veterinary Medicine; University of Saskatchewan; Saskatoon SK S7N 5B4 Canada
| | - Yeen Ten Hwang
- Saskatchewan Ministry of Environment; Government of Saskatchewan; Regina SK S4S 5W6 Canada
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27
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Potapov A, Merrill E, Pybus M, Lewis MA. Chronic Wasting Disease: Transmission Mechanisms and the Possibility of Harvest Management. PLoS One 2016; 11:e0151039. [PMID: 26963921 PMCID: PMC4786122 DOI: 10.1371/journal.pone.0151039] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 02/23/2016] [Indexed: 01/30/2023] Open
Abstract
We develop a model of CWD management by nonselective deer harvest, currently the most feasible approach available for managing CWD in wild populations. We use the model to explore the effects of 6 common harvest strategies on disease prevalence and to identify potential optimal harvest policies for reducing disease prevalence without population collapse. The model includes 4 deer categories (juveniles, adult females, younger adult males, older adult males) that may be harvested at different rates, a food-based carrying capacity, which influences juvenile survival but not adult reproduction or survival, and seasonal force of infection terms for each deer category under differing frequency-dependent transmission dynamics resulting from environmental and direct contact mechanisms. Numerical experiments show that the interval of transmission coefficients β where the disease can be controlled is generally narrow and efficiency of a harvest policy to reduce disease prevalence depends crucially on the details of the disease transmission mechanism, in particular on the intensity of disease transmission to juveniles and the potential differences in the behavior of older and younger males that influence contact rates. Optimal harvest policy to minimize disease prevalence for each of the assumed transmission mechanisms is shown to depend on harvest intensity. Across mechanisms, a harvest that focuses on antlered deer, without distinguishing between age classes reduces disease prevalence most consistently, whereas distinguishing between young and older antlered deer produces higher uncertainty in the harvest effects on disease prevalence. Our results show that, despite uncertainties, a modelling approach can determine classes of harvest strategy that are most likely to be effective in combatting CWD.
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Affiliation(s)
- Alex Potapov
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- Centre for Mathematical Biology, University of Alberta, Edmonton, Alberta, Canada
- Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
| | - Evelyn Merrill
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Margo Pybus
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- Alberta Sustainable Resource Development, Edmonton, Alberta, Canada
| | - Mark A. Lewis
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- Centre for Mathematical Biology, University of Alberta, Edmonton, Alberta, Canada
- Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, Alberta, Canada
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Al-Arydah M, Croteau MC, Oraby T, Smith RJ, Krewski D. Applications of mathematical modeling in managing the spread of chronic wasting disease (CWD) in wild deer under alternative harvesting scenarios. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2016; 79:690-699. [PMID: 27556563 DOI: 10.1080/15287394.2016.1174001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The application of a recently developed mathematical model for predicting the spread of chronic wasting disease (CWD) in wild deer was assessed under different scenarios where harvesting is employed in disease management. A process-based mathematical model for CWD transmission in wild deer populations was recently developed and parameterized by Al-arydah et al. (2011) to provide a scientific basis for understanding the factors that affect spread of CWD and evaluate concomitant disease-control strategies. The impact of gender on CWD transmission was shown to have a significant influence on the spread of the disease in the wild. Our model demonstrates a range of harvesting rates in which CWD is controlled and deer populations survive. However, if harvesting rates are too low, the disease remains endemic for decades. Conversely, the Canadian deer population is eradicated if harvesting rates are excessive. Future investigation includes building the model to assess the spread of CWD under different disease-management scenarios.
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Affiliation(s)
- M Al-Arydah
- a Masdar Institute of Science and Technology , Abu Dhabi , UAE
| | - M C Croteau
- b McLaughlin Centre for Population Health Risk Assessment , University of Ottawa , Ottawa , Ontario , Canada
| | - T Oraby
- c School of Mathematical and Statistical Sciences , University of Texas Rio Grande Valley , Edinburg , Texas , USA
| | - R J Smith
- d Department of Mathematics and Faculty of Medicine , University of Ottawa , Ottawa , Ontario , Canada
| | - D Krewski
- b McLaughlin Centre for Population Health Risk Assessment , University of Ottawa , Ottawa , Ontario , Canada
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Russell RE, Gude JA, Anderson NJ, Ramsey JM. Identifying priority chronic wasting disease surveillance areas for mule deer in Montana. J Wildl Manage 2015. [DOI: 10.1002/jwmg.914] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Robin E. Russell
- US Geological Survey; National Wildlife Health Center; 6006 Schroeder Road Madison WI 53711 USA
| | - Justin A. Gude
- Montana Fish; Wildlife and Parks; 1420 East 6th Avenue Helena MT 59620 USA
| | - Neil J. Anderson
- Montana Fish; Wildlife, and Parks; 1400 South 19th Avenue Bozeman MT 59717 USA
| | - Jennifer M. Ramsey
- Montana Fish; Wildlife, and Parks; 1400 South 19th Avenue Bozeman MT 59717 USA
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Magle SB, Kardash LH, Rothrock AO, Chamberlin JC, Mathews NE. Movements and Habitat Interactions of White-tailed Deer: Implications for Chronic Wasting Disease Management. AMERICAN MIDLAND NATURALIST 2015. [DOI: 10.1674/amid-173-02-267-282.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Schauber EM, Nielsen CK, Kjær LJ, Anderson CW, Storm DJ. Social affiliation and contact patterns among white-tailed deer in disparate landscapes: implications for disease transmission. J Mammal 2015; 96:16-28. [PMID: 26937044 PMCID: PMC4668922 DOI: 10.1093/jmammal/gyu027] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In social species, individuals contact members of the same group much more often than those of other groups, particularly for contacts that could directly transmit disease agents. This disparity in contact rates violates the assumptions of simple disease models, hinders disease spread between groups, and could decouple disease transmission from population density. Social behavior of white-tailed deer has important implications for the long-term dynamics and impact of diseases such as bovine tuberculosis and chronic wasting disease (CWD), so expanding our understanding of their social system is important. White-tailed deer form matrilineal groups, which inhabit stable home ranges that overlap somewhat with others-a pattern intermediate between mass-action and strict territoriality. To quantify how group membership affects their contact rates and document the spectrum of social affiliation, we analyzed location data from global positioning system (GPS) collars on female and juvenile white-tailed deer in 2 study areas: near Carbondale in forest-dominated southern Illinois (2002-2006) and near Lake Shelbyville in agriculture-dominated central Illinois (2006-2009). For each deer dyad (i.e., 2 individual deer with sufficient overlapping GPS data), we measured space-use overlap, correlation of movements, direct contact rate (simultaneous GPS locations < 10 m apart), and indirect contact rate (GPS locations < 10 m apart when offset by 1 or 3 days). Direct contact rates were substantially higher for within-group dyads than between-group dyads, but group membership had little apparent effect on indirect contact rates. The group membership effect on direct contact rates was strongest in winter and weakest in summer, with no apparent difference between study areas. Social affiliations were not dichotomous, with some deer dyads showing loose but positive affiliation. Even for obvious within-group dyads, their strength of affiliation fluctuated between years, seasons, and even days. Our findings highlight the poor fit between deer behavior and simple models of disease transmission and, combined with previous infection data, suggest that direct contact is the primary driver of CWD transmission among free-living female and juvenile white-tailed deer.
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Affiliation(s)
| | - Clayton K. Nielsen
- Cooperative Wildlife Research Laboratory, Southern Illinois University(Mail Code 6504), Carbondale, IL 62901, USA(EMS, CKN, LJK, CWA, DJS)
- Department of Zoology, Southern Illinois University(Mail Code 6501), Carbondale, IL 62901, USA(EMS, LJK, CWA, DJS)
- Department of Forestry, Southern Illinois University(Mail Code 4411), Carbondale, IL 62901, USA(CKN)
- Center for Ecology, Southern Illinois University(Mail Code 317), Carbondale, IL62901, USA(EMS, CKN)
| | - Lene J. Kjær
- Cooperative Wildlife Research Laboratory, Southern Illinois University(Mail Code 6504), Carbondale, IL 62901, USA(EMS, CKN, LJK, CWA, DJS)
- Department of Zoology, Southern Illinois University(Mail Code 6501), Carbondale, IL 62901, USA(EMS, LJK, CWA, DJS)
- Department of Forestry, Southern Illinois University(Mail Code 4411), Carbondale, IL 62901, USA(CKN)
- Center for Ecology, Southern Illinois University(Mail Code 317), Carbondale, IL62901, USA(EMS, CKN)
| | - Charles W. Anderson
- Cooperative Wildlife Research Laboratory, Southern Illinois University(Mail Code 6504), Carbondale, IL 62901, USA(EMS, CKN, LJK, CWA, DJS)
- Department of Zoology, Southern Illinois University(Mail Code 6501), Carbondale, IL 62901, USA(EMS, LJK, CWA, DJS)
- Department of Forestry, Southern Illinois University(Mail Code 4411), Carbondale, IL 62901, USA(CKN)
- Center for Ecology, Southern Illinois University(Mail Code 317), Carbondale, IL62901, USA(EMS, CKN)
| | - Daniel J. Storm
- Cooperative Wildlife Research Laboratory, Southern Illinois University(Mail Code 6504), Carbondale, IL 62901, USA(EMS, CKN, LJK, CWA, DJS)
- Department of Zoology, Southern Illinois University(Mail Code 6501), Carbondale, IL 62901, USA(EMS, LJK, CWA, DJS)
- Department of Forestry, Southern Illinois University(Mail Code 4411), Carbondale, IL 62901, USA(CKN)
- Center for Ecology, Southern Illinois University(Mail Code 317), Carbondale, IL62901, USA(EMS, CKN)
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Vasilyeva O, Oraby T, Lutscher F. Aggregation and environmental transmission in Chronic Wasting Disease. MATHEMATICAL BIOSCIENCES AND ENGINEERING : MBE 2015; 12:209-231. [PMID: 25811337 DOI: 10.3934/mbe.2015.12.209] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Disease transmission depends on the interplay between the infectious agent and the behavior of the host. Some diseases, such as Chronic Wasting Disease, can be transmitted directly between hosts as well as indirectly via the environment. The social behavior of hosts affects both of these pathways, and a successful intervention requires knowledge of the relative influence of the different etiological and behavioral aspects of the disease. We develop a strategic differential equation model for Chronic Wasting Disease and include direct and indirect transmission as well as host aggregation into our model. We calculate the basic reproduction number and perform a sensitivity analysis based on Latin hypercube sampling from published parameter values. We find conditions for the existence of an endemic equilibrium, and show that, under a certain mild assumption on parameters, the model does not exhibit a backward bifurcation or bistability. Hence, the basic reproduction number constitutes the disease elimination threshold. We find that the prevalence of the disease decreases with host aggregation and increases with the lifespan of the infectious agent in the environment.
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Affiliation(s)
- Olga Vasilyeva
- Department of Mathematics, Christopher Newport University, 1 Avenue of the Arts, Newport News, VA 23606, United States.
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Lavelle MJ, Fischer JW, Phillips GE, Hildreth AM, Campbell TA, Hewitt DG, Hygnstrom SE, Vercauteren KC. Assessing Risk of Disease Transmission: Direct Implications for an Indirect Science. Bioscience 2014. [DOI: 10.1093/biosci/biu055] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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34
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Landscape Aesthetics and the Scenic Drivers of Amenity Migration in the New West: Naturalness, Visual Scale, and Complexity. LAND 2014. [DOI: 10.3390/land3020390] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Jennelle CS, Henaux V, Wasserberg G, Thiagarajan B, Rolley RE, Samuel MD. Transmission of chronic wasting disease in Wisconsin white-tailed deer: implications for disease spread and management. PLoS One 2014; 9:e91043. [PMID: 24658535 PMCID: PMC3962341 DOI: 10.1371/journal.pone.0091043] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Accepted: 02/07/2014] [Indexed: 11/27/2022] Open
Abstract
Few studies have evaluated the rate of infection or mode of transmission for wildlife diseases, and the implications of alternative management strategies. We used hunter harvest data from 2002 to 2013 to investigate chronic wasting disease (CWD) infection rate and transmission modes, and address how alternative management approaches affect disease dynamics in a Wisconsin white-tailed deer population. Uncertainty regarding demographic impacts of CWD on cervid populations, human and domestic animal health concerns, and potential economic consequences underscore the need for strategies to control CWD distribution and prevalence. Using maximum-likelihood methods to evaluate alternative multi-state deterministic models of CWD transmission, harvest data strongly supports a frequency-dependent transmission structure with sex-specific infection rates that are two times higher in males than females. As transmissible spongiform encephalopathies are an important and difficult-to-study class of diseases with major economic and ecological implications, our work supports the hypothesis of frequency-dependent transmission in wild deer at a broad spatial scale and indicates that effective harvest management can be implemented to control CWD prevalence. Specifically, we show that harvest focused on the greater-affected sex (males) can result in stable population dynamics and control of CWD within the next 50 years, given the constraints of the model. We also provide a quantitative estimate of geographic disease spread in southern Wisconsin, validating qualitative assessments that CWD spreads relatively slowly. Given increased discovery and distribution of CWD throughout North America, insights from our study are valuable to management agencies and to the general public concerned about the impacts of CWD on white-tailed deer populations.
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Affiliation(s)
- Christopher S. Jennelle
- Department of Forest and Wildlife Ecology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Viviane Henaux
- Department of Forest and Wildlife Ecology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Gideon Wasserberg
- Biology Department, University of North Carolina, Greensboro, North Carolina, United States of America
| | - Bala Thiagarajan
- Department of Forest and Wildlife Ecology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Robert E. Rolley
- Wisconsin Department of Natural Resources, Madison, Wisconsin, United States of America
| | - Michael D. Samuel
- U.S. Geological Survey, Wisconsin Cooperative Wildlife Research Unit, University of Wisconsin, Madison, Wisconsin, United States of America
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36
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Monello RJ, Powers JG, Hobbs NT, Spraker TR, Watry MK, Wild MA. Survival and population growth of a free-ranging elk population with a long history of exposure to chronic wasting disease. J Wildl Manage 2014. [DOI: 10.1002/jwmg.665] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Ryan J. Monello
- Biological Resource Management Division; National Park Service; 1201 Oakridge STE 200 Fort Collins CO 80525
| | - Jenny G. Powers
- Biological Resource Management Division; National Park Service; 1201 Oakridge STE 200 Fort Collins CO 80525
| | - N. Thompson Hobbs
- Natural Resource Ecology Laboratory and Graduate Degree Program in Ecology; Colorado State University; Fort Collins CO 80523
| | - Terry R. Spraker
- Colorado State Diagnostic Laboratory; College of Veterinary Medicine; Colorado State University; Fort Collins CO 80523
| | - Mary Kay Watry
- Rocky Mountain National Park; National Park Service; Estes Park CO 80517
| | - Margaret A. Wild
- Biological Resource Management Division; National Park Service; 1201 Oakridge STE 200 Fort Collins CO 80525
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37
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Ramsey DSL, O'brien DJ, Cosgrove MK, Rudolph BA, Locher AB, Schmitt SM. Forecasting eradication of bovine tuberculosis in Michigan white-tailed deer. J Wildl Manage 2014. [DOI: 10.1002/jwmg.656] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- David S. L. Ramsey
- Arthur Rylah Institute for Environmental Research; Department of Environment and Primary Industries; 123 Brown Street Heidelberg Victoria 3084 Australia
| | - Daniel J. O'brien
- Wildlife Disease Laboratory; Michigan Department of Natural Resources; 4125 Beaumont Road Room 250 Lansing MI 48910 USA
| | - Melinda K. Cosgrove
- Wildlife Disease Laboratory; Michigan Department of Natural Resources; 4125 Beaumont Road Room 250 Lansing MI 48910 USA
| | - Brent A. Rudolph
- Rose Lake Wildlife Research Center; Michigan Department of Natural Resources; 8562 E. Stoll Road East Lansing MI 48823 USA
| | - Alexandra B. Locher
- Department of Biology; 321 Henry Hall; Grand Valley State University; Allendale MI 49401 USA
| | - Stephen M. Schmitt
- Wildlife Disease Laboratory; Michigan Department of Natural Resources; 4125 Beaumont Road Room 250 Lansing MI 48910 USA
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38
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Manjerovic MB, Green ML, Mateus-Pinilla N, Novakofski J. The importance of localized culling in stabilizing chronic wasting disease prevalence in white-tailed deer populations. Prev Vet Med 2014; 113:139-45. [DOI: 10.1016/j.prevetmed.2013.09.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 09/11/2013] [Accepted: 09/14/2013] [Indexed: 01/23/2023]
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Oraby T, Vasilyeva O, Krewski D, Lutscher F. Modeling seasonal behavior changes and disease transmission with application to chronic wasting disease. J Theor Biol 2013; 340:50-9. [PMID: 24035840 DOI: 10.1016/j.jtbi.2013.09.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Revised: 07/11/2013] [Accepted: 09/03/2013] [Indexed: 01/17/2023]
Abstract
Behavior and habitat of wildlife animals change seasonally according to environmental conditions. Mathematical models need to represent this seasonality to be able to make realistic predictions about the future of a population and the effectiveness of human interventions. Managing and modeling disease in wild animal populations requires particular care in that disease transmission dynamics is a critical consideration in the etiology of both human and animal diseases, with different transmission paradigms requiring different disease risk management strategies. Since transmission of infectious diseases among wildlife depends strongly on social behavior, mechanisms of disease transmission could also change seasonally. A specific consideration in this regard confronted by modellers is whether the contact rate between individuals is density-dependent or frequency-dependent. We argue that seasonal behavior changes could lead to a seasonal shift between density and frequency dependence. This hypothesis is explored in the case of chronic wasting disease (CWD), a fatal disease that affects deer, elk and moose in many areas of North America. Specifically, we introduce a strategic CWD risk model based on direct disease transmission that accounts for the seasonal change in the transmission dynamics and habitats occupied, guided by information derived from cervid ecology. The model is composed of summer and winter susceptible-infected (SI) equations, with frequency-dependent and density-dependent transmission dynamics, respectively. The model includes impulsive birth events with density-dependent birth rate. We determine the basic reproduction number as a weighted average of two seasonal reproduction numbers. We parameterize the model from data derived from the scientific literature on CWD and deer ecology, and conduct global and local sensitivity analyses of the basic reproduction number. We explore the effectiveness of different culling strategies for the management of CWD: although summer culling seems to be an effective disease eradication strategy, the total culling rate is limited by the requirement to preserve the herd.
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Affiliation(s)
- Tamer Oraby
- McLaughlin Centre for Population Health Risk Assessment, University of Ottawa, Ottawa, Ontario, Canada.
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40
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Berentsen AR, Miller RS, Misiewicz R, Malmberg JL, Dunbar MR. Characteristics of white-tailed deer visits to cattle farms: implications for disease transmission at the wildlife–livestock interface. EUR J WILDLIFE RES 2013. [DOI: 10.1007/s10344-013-0760-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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41
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Magle SB, Samuel MD, Van Deelen TR, Robinson SJ, Mathews NE. Evaluating spatial overlap and relatedness of white-tailed deer in a chronic wasting disease management zone. PLoS One 2013; 8:e56568. [PMID: 23437171 PMCID: PMC3577845 DOI: 10.1371/journal.pone.0056568] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 01/14/2013] [Indexed: 11/19/2022] Open
Abstract
Wildlife disease transmission, at a local scale, can occur from interactions between infected and susceptible conspecifics or from a contaminated environment. Thus, the degree of spatial overlap and rate of contact among deer is likely to impact both direct and indirect transmission of infectious diseases such chronic wasting disease (CWD) or bovine tuberculosis. We identified a strong relationship between degree of spatial overlap (volume of intersection) and genetic relatedness for female white-tailed deer in Wisconsin's area of highest CWD prevalence. We used volume of intersection as a surrogate for contact rates between deer and concluded that related deer are more likely to have contact, which may drive disease transmission dynamics. In addition, we found that age of deer influences overlap, with fawns exhibiting the highest degree of overlap with other deer. Our results further support the finding that female social groups have higher contact among related deer which can result in transmission of infectious diseases. We suggest that control of large social groups comprised of closely related deer may be an effective strategy in slowing the transmission of infectious pathogens, and CWD in particular.
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Affiliation(s)
- Seth B Magle
- Urban Wildlife Institute, Lincoln Park Zoo, Chicago, Illinois, USA.
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42
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43
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Storm DJ, Samuel MD, Rolley RE, Shelton P, Keuler NS, Richards BJ, Van Deelen TR. Deer density and disease prevalence influence transmission of chronic wasting disease in white-tailed deer. Ecosphere 2013. [DOI: 10.1890/es12-00141.1] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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44
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Lavelle MJ, Hygnstrom SE, Hildreth AM, Campbell TA, Long DB, Hewitt DG, Beringer J, VerCauteren KC. Utility of improvised video-camera collars for collecting contact data from white-tailed deer: Possibilities in disease transmission studies. WILDLIFE SOC B 2012. [DOI: 10.1002/wsb.216] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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45
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Al-Arydah M, Smith RJ, Lutscher F. Modeling Gender-Structured Wildlife Diseases with Harvesting: Chronic Wasting Disease as an Example. ACTA ACUST UNITED AC 2012. [DOI: 10.5402/2012/802450] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Chronic wasting disease (CWD) is a prion infectious disease that affects members of the deer family in North America. Concerns about the economic consequences of the presence of CWD have led management agencies to seek effective strategies to control CWD distribution and prevalence. Current mathematical models are either based on complex simulations or overly simplified compartmental models. We develop a mathematical model that includes gender structure to describe CWD in a logistically growing population. The model includes harvesting as a management strategy for the disease. We determine the stability conditions of the disease-free equilibrium for the model and calculate the basic reproduction number. We find an optimum interval of harvesting: with too little harvesting, the disease persists, whereas too much harvesting results in extinction of the population. A sensitivity analysis shows that the disease threshold is more sensitive to female than male harvesting and that harvesting has the greatest effect on the basic reproduction number. However, while harvesting may be a way to control CWD, the range of admissible harvesting rates may be very narrow, depending on other parameters.
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Affiliation(s)
- Mo'tassem Al-Arydah
- Department of Mathematics, The University of Ottawa, Ottawa, ON, Canada K1N 6N5
| | - Robert J. Smith
- Department of Mathematics and Faculty of Medicine, The University of Ottawa, Ottawa, ON, Canada K1N 6N5
| | - Frithjof Lutscher
- Department of Mathematics, The University of Ottawa, Ottawa, ON, Canada K1N 6N5
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46
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Robert K, Garant D, Pelletier F. Keep in touch: Does spatial overlap correlate with contact rate frequency? J Wildl Manage 2012. [DOI: 10.1002/jwmg.435] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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47
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Potapov A, Merrill E, Lewis MA. Wildlife disease elimination and density dependence. Proc Biol Sci 2012; 279:3139-45. [PMID: 22593103 DOI: 10.1098/rspb.2012.0520] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Disease control by managers is a crucial response to emerging wildlife epidemics, yet the means of control may be limited by the method of disease transmission. In particular, it is widely held that population reduction, while effective for controlling diseases that are subject to density-dependent (DD) transmission, is ineffective for controlling diseases that are subject to frequency-dependent (FD) transmission. We investigate control for horizontally transmitted diseases with FD transmission where the control is via culling or harvest that is non-selective with respect to infection and the population can compensate through DD recruitment or survival. Using a mathematical model, we show that culling or harvesting can eradicate the disease, even when transmission dynamics are FD. Eradication can be achieved under FD transmission when DD birth or recruitment induces compensatory growth of new, healthy individuals, which has the net effect of reducing disease prevalence by dilution. We also show that if harvest is used simultaneously with vaccination, and there is high enough transmission coefficient, application of both controls may be less efficient than vaccination alone. We illustrate the effects of these control approaches on disease prevalence for chronic wasting disease in deer where the disease is transmitted directly among deer and through the environment.
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Affiliation(s)
- Alex Potapov
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
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Rees EE, Merrill EH, Bollinger TK, Hwang YT, Pybus MJ, Coltman DW. Targeting the detection of chronic wasting disease using the hunter harvest during early phases of an outbreak in Saskatchewan, Canada. Prev Vet Med 2011; 104:149-59. [PMID: 22137503 DOI: 10.1016/j.prevetmed.2011.10.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 10/25/2011] [Accepted: 10/28/2011] [Indexed: 10/14/2022]
Abstract
Chronic wasting disease (CWD) is a fatal disease of North American cervids that was first detected in a wild, hunter-shot deer in Saskatchewan along the border with Alberta in Canada in 2000. Spatially explicit models for assessing factors affecting disease detection are needed to guide surveillance and control programs. Spatio-temporal patterns in CWD prevalence can be complicated by variation in individual infection probability and sampling biases. We assessed hunter harvest data of mule deer (Odocoileus hemionus) and white-tailed deer (Odocoileus virginianus) during the early phases of an outbreak in Saskatchewan (i.e., 2002-2007) for targeting the detection of CWD by defining (1) where to look, and (2) how much effort to use. First, we accounted for known demographic heterogeneities in infection to model the probability, P(E), that a harvested deer was infected with CWD given characteristics of the harvest location. Second, in areas where infected deer were harvested we modelled the probability, P(D), of the hunter harvest re-detecting CWD within sample units of varying size (9-54 km(2)) given the demographics of harvested deer and time since first detection in the study area. Heterogeneities in host infection were consistent with those reported elsewhere: mule deer 3.7 times >white-tailed deer, males 1.8 times>females, and quadratically related to age in both sexes. P(E) increased with number of years since the first detection in our study area (2002) and proximity to known disease sources, and also varied with distance to the South Saskatchewan River and small creek drainages, terrain ruggedness, and extent of agriculture lands within a 3 km radius of the harvest. The majority (75%) of new CWD-positive deer from our sample were found within 20 km of infected deer harvested in the previous year, while approximately 10% were greater than 40 km. P(D) modelled at 18 km(2) was best supported, but for all scales, P(D) depended on the number of harvested deer and time since the first infected deer was harvested. Within an 18 km(2) sampling unit, there was an 80% probability of detecting a CWD-positive deer with 16 harvested deer five years after the initial infected harvest. Identifying where and how much to sample to detect CWD can improve targeted surveillance programs early in the outbreak of the disease when based on hunter harvest.
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Affiliation(s)
- Erin E Rees
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada.
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