1
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van Beest FM, Schmidt NM, Frederiksen ML, Krogh AKH, Petersen HH, Hansson SV. Direct and Indirect Linkages Between Trace Element Status and Health Indicators - a Multi-tissue Case-Study of Two Deer Species in Denmark. Biol Trace Elem Res 2024; 202:3623-3638. [PMID: 37917250 PMCID: PMC11144132 DOI: 10.1007/s12011-023-03926-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 10/22/2023] [Indexed: 11/04/2023]
Abstract
Measuring trace element concentrations in tissue can be a valuable approach to monitor animal health status. Temporal variation in the absorption, transport, and storage of elements between different tissues can, however, complicate the assessment of element-health relationships. Here, we measured concentrations of selected essential (copper (Cu), zinc (Zn), selenium (Se)) and non-essential (arsenic (As), cadmium (Cd), lead (Pb)) trace elements within blood, liver, kidney, and hair of fallow deer (Dama dama; N=20) and red deer (Cervus elaphus; N=21). Using multivariate regression and structural equation models, we estimated direct and indirect linkages between tissue-specific trace element profiles and long- (body condition) and short-term (serum protein biomarkers for acute inflammation, infection, and malnutrition) health indicators. Trace element concentrations varied markedly and were weakly correlated among tissues, with the exception of Se. After accounting for sex- and site-differences in trace element concentrations, body condition of red deer was directly, and positively, associated to trace element status in liver and hair, but not in kidney. For both deer species, trace element status in blood was directly linked to serum protein status with an indirect positive association to deer body condition. For fallow deer, no direct association between trace element status and body condition was detected in any of the tissues, possibly because of elemental homeostasis, and because all individuals were in good clinical health. This study shows that hair can serve as an effective, non-invasive, biomarker in deer health assessments, yet, to fully uncover trace element-health relationships a variety of sample matrices is preferred.
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Affiliation(s)
- Floris M van Beest
- Department of Ecoscience, Aarhus University, Frederiksborgvej 399, DK-4000, Roskilde, Denmark.
| | - Niels M Schmidt
- Department of Ecoscience, Aarhus University, Frederiksborgvej 399, DK-4000, Roskilde, Denmark
| | | | - Anne K H Krogh
- Department of Veterinary Clinical Sciences, University of Copenhagen, Dyrlægevej 16, DK-1870, Frederiksberg, Denmark
| | - Heidi H Petersen
- Center for Diagnostics, Technical University of Denmark, Kemitorvet, DK-2800, Kgs. Lyngby, Denmark
| | - Sophia V Hansson
- Laboratoire Ecologie Fonctionnelle et Environnement (UMR- 5245), CNRS, Université de Toulouse, Ave. de l'Agrobiopole, 31326, Castanet Tolosan, France
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2
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Hearst S, Huang M, Johnson B, Rummells E. Identifying Potential Super-Spreaders and Disease Transmission Hotspots Using White-Tailed Deer Scraping Networks. Animals (Basel) 2023; 13:1171. [PMID: 37048427 PMCID: PMC10093032 DOI: 10.3390/ani13071171] [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: 01/07/2023] [Revised: 03/22/2023] [Accepted: 03/22/2023] [Indexed: 03/29/2023] Open
Abstract
White-tailed deer (Odocoileus virginianus, WTD) spread communicable diseases such the zoonotic coronavirus SARS-CoV-2, which is a major public health concern, and chronic wasting disease (CWD), a fatal, highly contagious prion disease occurring in cervids. Currently, it is not well understood how WTD are spreading these diseases. In this paper, we speculate that "super-spreaders" mediate disease transmission via direct social interactions and indirectly via body fluids exchanged at scrape sites. Super-spreaders are infected individuals that infect more contacts than other infectious individuals within a population. In this study, we used network analysis from scrape visitation data to identify potential super-spreaders among multiple communities of a rural WTD herd. We combined local network communities to form a large region-wide social network consisting of 96 male WTD. Analysis of WTD bachelor groups and random network modeling demonstrated that scraping networks depict real social networks, allowing detection of direct and indirect contacts, which could spread diseases. Using this regional network, we model three major types of potential super-spreaders of communicable disease: in-degree, out-degree, and betweenness potential super-spreaders. We found out-degree and betweenness potential super-spreaders to be critical for disease transmission across multiple communities. Analysis of age structure revealed that potential super-spreaders were mostly young males, less than 2.5 years of age. We also used social network analysis to measure the outbreak potential across the landscape using a new technique to locate disease transmission hotspots. To model indirect transmission risk, we developed the first scrape-to-scrape network model demonstrating connectivity of scrape sites. Comparing scrape betweenness scores allowed us to locate high-risk transmission crossroads between communities. We also monitored predator activity, hunting activity, and hunter harvests to better understand how predation influences social networks and potential disease transmission. We found that predator activity significantly influenced the age structure of scraping communities. We assessed disease-management strategies by social-network modeling using hunter harvests or removal of potential super-spreaders, which fragmented WTD social networks reducing the potential spread of disease. Overall, this study demonstrates a model capable of predicting potential super-spreaders of diseases, outlines methods to locate transmission hotspots and community crossroads, and provides new insight for disease management and outbreak prevention strategies.
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Affiliation(s)
- Scoty Hearst
- The Department of Chemistry and Biochemistry, Mississippi College, Clinton, MS 39056, USA
| | - Miranda Huang
- Department of Wildlife, Fisheries, and Aquaculture, Mississippi State University, Starkville, MS 39762, USA
| | - Bryant Johnson
- The Department of Chemistry and Biochemistry, Mississippi College, Clinton, MS 39056, USA
| | - Elijah Rummells
- The Department of Chemistry and Biochemistry, Mississippi College, Clinton, MS 39056, USA
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3
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Kjær LJ, Schauber EM. The effect of landscape, transmission mode and social behavior on disease transmission: Simulating the transmission of chronic wasting disease in white-tailed deer (Odocoileus virginianus) populations using a spatially explicit agent-based model. Ecol Modell 2022. [DOI: 10.1016/j.ecolmodel.2022.110114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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4
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Carver S, Peters A, Richards SA. Model Integrated Disease Management to facilitate effective translatable solutions for wildlife disease issues. J Appl Ecol 2022. [DOI: 10.1111/1365-2664.14298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Scott Carver
- Department of Biological Sciences University of Tasmania
| | - Andrew Peters
- School of Animal and Veterinary Sciences Charles Sturt University
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5
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Uzal A, Martinez-Artero J, Ordiz A, Zarzo-Arias A, Penteriani V. Habitat characteristics around dens in female brown bears with cubs are density dependent. MAMMAL RES 2022. [DOI: 10.1007/s13364-022-00640-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Abstract
The mechanisms determining habitat use in animal populations have important implications for population dynamics, conservation, and management. Here, we investigated how an increase in annual numbers of brown bear females with cubs of the year (FCOY) in a growing, yet threatened population, could explain differences in the habitat characteristics around reproductive dens. Habitat characteristics around FCOY dens were compared between a low bear density period (1995–2005) and a period when the population was increasing (2006–2016). We also compared the distance to the nearest breeding area and to all other breeding areas observed during the same year. The results suggested that during the second period, breeding areas were closer to rivers, fruit trees, and anthropogenic sources of disturbance (trails, highways) than in 1995–2005. There were also shorter distances to the closest neighboring breeding area, while the mean distance among FCOY breeding areas increased as the population grew and expanded at the landscape level. These changes may reflect that the best den locations were increasingly occupied (i.e., ideal-despotic distribution), and may be further explained by the avoidance of conspecifics by FCOY in a critical time of the year, when newborn cubs are most vulnerable. We suggest that both density-dependent factors and human-related features of the landscape are crucial to understanding long-term dynamics in the habitat use of a threatened species.
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6
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Islam MR, Bulut U, Feria-Arroyo TP, Tyshenko MG, Oraby T. Modeling the Impact of Climate Change on Cervid Chronic Wasting Disease in Semi-Arid South Texas. FRONTIERS IN EPIDEMIOLOGY 2022; 2:889280. [PMID: 38455276 PMCID: PMC10910938 DOI: 10.3389/fepid.2022.889280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 04/01/2022] [Indexed: 03/09/2024]
Abstract
Chronic wasting disease (CWD) is a spongiform encephalopathy disease caused by the transmission of infectious prion agents. CWD is a fatal disease that affects wild and farmed cervids in North America with few cases reported overseas. Social interaction of cervids, feeding practices by wildlife keepers and climate effects on the environmental carrying capacity all can affect CWD transmission in deer. Wildlife deer game hunting is economically important to the semi-arid South Texas region and is affected by climate change. In this paper, we model and investigate the effect of climate change on the spread of CWD using typical climate scenarios. We use a system of impulsive differential equations to depict the transmission of CWD between different age groups and gender of cervids. The carrying capacity and contact rates are assumed to depend on climate. Due to the polygamy of bucks, we use mating rates that depend on the number of bucks and does. We analyze the stability of the model and use simulations to study the effect of harvesting (culling) on eradicating the disease, given the climate of South Texas. We use typical climate change scenarios based on published data and our assumptions. For the climate indicator, we calculated and utilized the Standard Precipitation Evapotranspiration Index (SPEI). We found that climate change might hinder the efforts to reduce and effectively manage CWD as it becomes endemic to South Texas. The model shows the extinction of the deer population from this region is a likely outcome.
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Affiliation(s)
- Md Rafiul Islam
- Department of Mathematics, Iowa State University, Ames, IA, United States
| | - Ummugul Bulut
- Department of Mathematical, Physical, and Engineering Sciences, Texas A&M University-San Antonio, San Antonio, TX, United States
| | | | | | - Tamer Oraby
- School of Mathematical and Statistical Sciences, The University of Texas Rio Grande Valley, Edinburg, TX, United States
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7
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Gilbertson MLJ, Onorato D, Cunningham M, VandeWoude S, Craft ME. Paradoxes and synergies: Optimizing management of a deadly virus in an endangered carnivore. J Appl Ecol 2022; 59:1548-1558. [DOI: 10.1111/1365-2664.14165] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Dave Onorato
- Fish and Wildlife Research Institute Florida Fish and Wildlife Conservation Commission Naples FL USA
| | - Mark Cunningham
- Fish and Wildlife Research Institute, Florida Fish and Wildlife Conservation Commission Gainesville FL USA
| | - Sue VandeWoude
- Department of Microbiology, Immunology, and Pathology Colorado State University Fort Collins CO USA
| | - Meggan E. Craft
- Department of Veterinary Population Medicine University of Minnesota St Paul MN USA
- Department of Ecology, Evolution and Behavior University of Minnesota St Paul MN USA
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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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Hunting alters viral transmission and evolution in a large carnivore. Nat Ecol Evol 2022; 6:174-182. [PMID: 35087217 PMCID: PMC10111630 DOI: 10.1038/s41559-021-01635-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 11/24/2021] [Indexed: 11/09/2022]
Abstract
Hunting can fundamentally alter wildlife population dynamics but the consequences of hunting on pathogen transmission and evolution remain poorly understood. Here, we present a study that leverages a unique landscape-scale quasi-experiment coupled with pathogen-transmission tracing, network simulation and phylodynamics to provide insights into how hunting shapes feline immunodeficiency virus (FIV) dynamics in puma (Puma concolor). We show that removing hunting pressure enhances the role of males in transmission, increases the viral population growth rate and increases the role of evolutionary forces on the pathogen compared to when hunting was reinstated. Changes in transmission observed with the removal of hunting could be linked to short-term social changes while the male puma population increased. These findings are supported through comparison with a region with stable hunting management over the same time period. This study shows that routine wildlife management can have impacts on pathogen transmission and evolution not previously considered.
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10
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Ketz AC, Robinson SJ, Johnson CJ, Samuel MD. Pathogen‐mediated selection and management implications for white‐tailed deer exposed to chronic wasting disease. J Appl Ecol 2022. [DOI: 10.1111/1365-2664.14109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Alison C. Ketz
- Wisconsin Cooperative Research Unit Department of Forest and Wildlife Ecology University of Wisconsin Madison WI USA
| | - Stacie J. Robinson
- NOAA Hawaiian Monk Seal Research Program Pacific Islands Fisheries Science Center Honolulu HI USA
| | - Chad J. Johnson
- Medical Microbiology and Immunology University of Wisconsin Madison WI USA
| | - Michael D. Samuel
- Department of Forest and Wildlife Ecology University of Wisconsin Madison WI USA
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11
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CHRONIC WASTING DISEASE MODELING: AN OVERVIEW. J Wildl Dis 2021; 56:741-758. [PMID: 32544029 DOI: 10.7589/2019-08-213] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 11/13/2019] [Indexed: 11/20/2022]
Abstract
Chronic wasting disease (CWD) is an infectious and fatal prion disease occurring in the family Cervidae. To update the research community regarding the status quo of CWD epidemic models, we conducted a meta-analysis on CWD research. We collected data from peer-reviewed articles published since 1980, when CWD was first diagnosed, until December 2018. We explored the analytical methods used historically to understand CWD. We used 14 standardized variables to assess overall analytical approaches of CWD research communities, data used, and the modeling methods used. We found that CWD modeling initiated in the early 2000s and has increased since then. Connectivity of the research community was heavily reliant on a cluster of CWD researchers. Studies focused primarily on regression and compartment-based models, population-level approaches, and host species of game management concern. Similarly, CWD research focused on single populations, species, and locations, neglecting modeling using community ecology and biogeographic approaches. Chronic wasting disease detection relied on classic diagnostic methods with limited sensitivity for most stages of infection. Overall, we found that past modeling efforts generated a solid baseline for understanding CWD in wildlife and increased our knowledge on infectious prion ecology. Future analytical efforts should consider more sensitive diagnostic methods to quantify uncertainty and broader scale studies to elucidate CWD transmission beyond population-level approaches. Considering that infectious prions may not follow biological rules of well-known wildlife pathogens (i.e., viruses, bacteria, fungi), assumptions used when modeling other infectious disease may not apply for CWD. Chronic wasting disease is a new challenge in wildlife epidemiology.
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12
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Bozzuto C, Schmidt BR, Canessa S. Active responses to outbreaks of infectious wildlife diseases: objectives, strategies and constraints determine feasibility and success. Proc Biol Sci 2020; 287:20202475. [PMID: 33234080 DOI: 10.1098/rspb.2020.2475] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Emerging wildlife diseases are taking a heavy toll on animal and plant species worldwide. Mitigation, particularly in the initial epidemic phase, is hindered by uncertainty about the epidemiology and management of emerging diseases, but also by vague or poorly defined objectives. Here, we use a quantitative analysis to assess how the decision context of mitigation objectives, available strategies and practical constraints influences the decision of whether and how to respond to epidemics in wildlife. To illustrate our approach, we parametrized the model for European fire salamanders affected by Batrachochytrium salamandrivorans, and explored different combinations of conservation, containment and budgetary objectives. We found that in approximately half of those scenarios, host removal strategies perform equal to or worse than no management at all during a local outbreak, particularly where removal cannot exclusively target infected individuals. Moreover, the window for intervention shrinks rapidly if an outbreak is detected late or if a response is delayed. Clearly defining the decision context is, therefore, vital to plan meaningful responses to novel outbreaks. Explicitly stating objectives, strategies and constraints, if possible before an outbreak occurs, avoids wasting precious resources and creating false expectations about what can and cannot be achieved during the epidemic phase.
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Affiliation(s)
- Claudio Bozzuto
- Wildlife Analysis GmbH, Oetlisbergstrasse 38, 8053 Zurich, Switzerland
| | - Benedikt R Schmidt
- Institut für Evolutionsbiologie und Umweltwissenschaften, Universität Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland.,info fauna karch, UniMail, Bâtiment G, Bellevaux 51, 2000 Neuchâtel, Switzerland
| | - Stefano Canessa
- Wildlife Health Ghent, Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
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13
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Paterson JT, Butler C, Garrott R, Proffitt K. How sure are you? A web-based application to confront imperfect detection of respiratory pathogens in bighorn sheep. PLoS One 2020; 15:e0237309. [PMID: 32898140 PMCID: PMC7478830 DOI: 10.1371/journal.pone.0237309] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 07/26/2020] [Indexed: 11/18/2022] Open
Abstract
The relationships between host-pathogen population dynamics in wildlife are poorly understood. An impediment to progress in understanding these relationships is imperfect detection of diagnostic tests used to detect pathogens. If ignored, imperfect detection precludes accurate assessment of pathogen presence and prevalence, foundational parameters for deciphering host-pathogen dynamics and disease etiology. Respiratory disease in bighorn sheep (Ovis canadensis) is a significant impediment to their conservation and restoration, and effective management requires a better understanding of the structure of the pathogen communities. Our primary objective was to develop an easy-to-use and accessible web-based Shiny application that estimates the probability (with associated uncertainty) that a respiratory pathogen is present in a herd and its prevalence given imperfect detection. Our application combines the best-available information on the probabilities of detection for various respiratory pathogen diagnostic protocols with a hierarchical Bayesian model of pathogen prevalence. We demonstrated this application using four examples of diagnostic tests from three herds of bighorn sheep in Montana. For instance, one population with no detections of Mycoplasma ovipneumoniae (PCR assay) still had an 6% probability of the pathogen being present in the herd. Similarly, the apparent prevalence (0.32) of M. ovipneumoniae in another herd was a substantial underestimate of estimated true prevalence (0.46: 95% CI = [0.25, 0.71]). The negative bias of naïve prevalence increased as the probability of detection of testing protocols worsened such that the apparent prevalence of Mannheimia haemolytica (culture assay) in a herd (0.24) was less than one third that of estimated true prevalence (0.78: 95% CI = [0.43, 0.99]). We found a small difference in the estimates of the probability that Mannheimia spp. (culture assay) was present in one herd between the binomial sampling approach (0.24) and the hypergeometric approach (0.22). Ignoring the implications of imperfect detection and sampling variation for assessing pathogen communities in bighorn sheep can result in spurious inference on pathogen presence and prevalence, and potentially poorly informed management decisions. Our Shiny application makes the rigorous assessment of pathogen presence, prevalence and uncertainty straightforward, and we suggest it should be incorporated into a new paradigm of disease monitoring.
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Affiliation(s)
- J. Terrill Paterson
- Department of Ecology, Montana State University, Bozeman, MT, United States of America
- * E-mail:
| | - Carson Butler
- Fish and Wildlife Branch, Grand Teton National Park, Moose, WY, United States of America
| | - Robert Garrott
- Department of Ecology, Montana State University, Bozeman, MT, United States of America
| | - Kelly Proffitt
- Montana Fish Wildlife and Parks, Bozeman, MT, United States of America
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14
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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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15
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Hopkins SR, Fleming‐Davies AE, Belden LK, Wojdak JM. Systematic review of modelling assumptions and empirical evidence: Does parasite transmission increase nonlinearly with host density? Methods Ecol Evol 2020. [DOI: 10.1111/2041-210x.13361] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
| | - Arietta E. Fleming‐Davies
- Biology Department University of San Diego San Diego CA USA
- Department of Biology Radford University Radford VA USA
| | - Lisa K. Belden
- Department of Biological Sciences Virginia Tech Blacksburg VA USA
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16
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Rosen LE, Fogarty U, O’Keeffe JJ, Olea-Popelka FJ. Monitoring European badger (Meles meles) reproduction under evolving bovine tuberculosis management in Ireland. EUR J WILDLIFE RES 2019. [DOI: 10.1007/s10344-019-1340-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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17
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Mysterud A, Madslien K, Viljugrein H, Vikøren T, Andersen R, Güere ME, Benestad SL, Hopp P, Strand O, Ytrehus B, Røed KH, Rolandsen CM, Våge J. The demographic pattern of infection with chronic wasting disease in reindeer at an early epidemic stage. Ecosphere 2019. [DOI: 10.1002/ecs2.2931] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Affiliation(s)
- Atle Mysterud
- Centre for Ecological and Evolutionary Synthesis (CEES) Department of Biosciences University of Oslo NO‐0316 P.O. Box 1066 Blindern Oslo Norway
| | - Knut Madslien
- Norwegian Veterinary Institute NO‐0106 P.O. Box 750 Sentrum Oslo Norway
| | | | - Turid Vikøren
- Norwegian Veterinary Institute NO‐0106 P.O. Box 750 Sentrum Oslo Norway
| | - Roy Andersen
- Norwegian Institute for Nature Research (NINA) NO‐7485 P. O. Box 5685 Torgarden Trondheim Norway
| | - Mariella Evelyn Güere
- Department of Basic Sciences and Aquatic Medicine Norwegian University of Life Sciences NO‐0102 P.O. Box 369 Sentrum Oslo Norway
| | | | - Petter Hopp
- Norwegian Veterinary Institute NO‐0106 P.O. Box 750 Sentrum Oslo Norway
| | - Olav Strand
- Norwegian Institute for Nature Research (NINA) NO‐7485 P. O. Box 5685 Torgarden Trondheim Norway
| | - Bjørnar Ytrehus
- Norwegian Institute for Nature Research (NINA) NO‐7485 P. O. Box 5685 Torgarden Trondheim Norway
| | - Knut H. Røed
- Department of Basic Sciences and Aquatic Medicine Norwegian University of Life Sciences NO‐0102 P.O. Box 369 Sentrum Oslo Norway
| | - Christer M. Rolandsen
- Norwegian Institute for Nature Research (NINA) NO‐7485 P. O. Box 5685 Torgarden Trondheim Norway
| | - Jørn Våge
- Norwegian Veterinary Institute NO‐0106 P.O. Box 750 Sentrum Oslo Norway
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18
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Rivera NA, Brandt AL, Novakofski JE, Mateus-Pinilla NE. Chronic Wasting Disease In Cervids: Prevalence, Impact And Management Strategies. VETERINARY MEDICINE (AUCKLAND, N.Z.) 2019; 10:123-139. [PMID: 31632898 PMCID: PMC6778748 DOI: 10.2147/vmrr.s197404] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 09/10/2019] [Indexed: 11/23/2022]
Abstract
Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSE) that affects members of the cervidae family. The infectious agent is a misfolded isoform (PrPSC) of the host prion protein (PrPC). The replication of PrPSC initiates a cascade of developmental changes that spread from cell to cell, individual to individual, and that for some TSEs, has crossed the species barrier. CWD can be transmitted horizontally and vertically, and it is the only TSE that affects free-ranging wildlife. While other TSEs are under control and even declining, infection rates of CWD continue to grow and the disease distribution continues to expand in North America and around the world. Since the first reported case in 1967, CWD has spread infecting captive and free-ranging cervids in 26 states in the US, 3 Canadian provinces, 3 European countries and has been found in captive cervids in South Korea. CWD causes considerable ecologic, economic and sociologic impact, as this is a 100% fatal highly contagious infectious disease, with no treatment or cure available. Because some TSEs have crossed the species barrier, the zoonotic potential of CWD is a concern for human health and continues to be investigated. Here we review the characteristics of the CWD prion protein, mechanisms of transmission and the role of genetics. We discuss the characteristics that contribute to prevalence and distribution. We also discuss the impact of CWD and review the management strategies that have been used to prevent and control the spread of CWD.
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Affiliation(s)
- Nelda A Rivera
- Illinois Natural History Survey-Prairie Research Institute, University of Illinois Urbana-Champaign, Champaign, IL, USA
| | - Adam L Brandt
- Division of Natural Sciences, St. Norbert College, De Pere, WI, USA
| | - Jan E Novakofski
- Department of Animal Sciences, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Nohra E Mateus-Pinilla
- Illinois Natural History Survey-Prairie Research Institute, University of Illinois Urbana-Champaign, Champaign, IL, USA
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Bolzoni L, Bonacini E, Della Marca R, Groppi M. Optimal control of epidemic size and duration with limited resources. Math Biosci 2019; 315:108232. [PMID: 31330135 DOI: 10.1016/j.mbs.2019.108232] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 07/18/2019] [Accepted: 07/18/2019] [Indexed: 11/18/2022]
Abstract
The total number of infections (epidemic size) and the time needed for the infection to go extinct (epidemic duration) represent two of the main indicators for the severity of infectious disease epidemics in human and livestock. However, few attempts have been made to address the problem of minimizing at the same time the epidemic size and duration from a theoretical point of view by using optimal control theory. Here, we investigate the multi-objective optimal control problem aiming to minimize, through either vaccination or isolation, a suitable combination of epidemic size and duration when both maximum control effort and total amount of resources available during the entire epidemic period are limited. Application of Pontryagin's Maximum Principle to a Susceptible-Infected-Removed epidemic model, shows that, when the resources are not sufficient to maintain the maximum control effort for the entire duration of the epidemic, the optimal vaccination control admits only bang-bang solutions with one or two switches, while the optimal isolation control admits only bang-bang solutions with one switch. We also find that, especially when the maximum control effort is low, there may exist a trade-off between the minimization of the two objectives. Consideration of this conflict among objectives can be crucial in successfully tackling real-world problems, where different stakeholders with potentially different objectives are involved. Finally, the particular case of the minimum time optimal control problem with limited resources is discussed.
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Affiliation(s)
- Luca Bolzoni
- Risk Analysis and Genomic Epidemiology Unit, Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, Via dei Mercati 13, Parma 43126, Italy.
| | - Elena Bonacini
- Department of Mathematical, Physical and Computer Sciences, University of Parma, Parco Area delle Scienze 53/A, Parma 43124, Italy
| | - Rossella Della Marca
- Department of Mathematical, Physical and Computer Sciences, University of Parma, Parco Area delle Scienze 53/A, Parma 43124, Italy
| | - Maria Groppi
- Department of Mathematical, Physical and Computer Sciences, University of Parma, Parco Area delle Scienze 53/A, Parma 43124, Italy
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20
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Tanner E, White A, Lurz PWW, Gortázar C, Díez-Delgado I, Boots M. The Critical Role of Infectious Disease in Compensatory Population Growth in Response to Culling. Am Nat 2019; 194:E1-E12. [PMID: 31251646 DOI: 10.1086/703437] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Despite the ubiquity of disease in nature, the role that disease dynamics play in the compensatory growth response to harvesting has been ignored. We use a mathematical approach to show that harvesting can lead to compensatory growth due to a release from disease-induced mortality. Our findings imply that culling in systems that harbor virulent parasites can reduce disease prevalence and increase population density. Our models predict that this compensation occurs for a broad range of infectious disease characteristics unless the disease induces long-lasting immunity in hosts. Our key insight is that a population can be regulated at a similar density by disease or at reduced prevalence by a combination of culling and disease. We illustrate our predictions with a system-specific model representing wild boar tuberculosis infection, parameterized for central Spain, and find significant compensation to culling. Given that few wildlife diseases are likely to induce long-lived immunity, populations with virulent diseases may often be resilient to harvesting.
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Carr AN, Milleson MP, Hernández FA, Merrill HR, Avery ML, Wisely SM. Wildlife Management Practices Associated with Pathogen Exposure in Non-Native Wild Pigs in Florida, U.S. Viruses 2018; 11:E14. [PMID: 30587789 PMCID: PMC6356989 DOI: 10.3390/v11010014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 12/11/2018] [Accepted: 12/20/2018] [Indexed: 12/15/2022] Open
Abstract
Land use influences disease emergence by changing the ecological dynamics of humans, wildlife, domestic animals, and pathogens. This is a central tenet of One Health, and one that is gaining momentum in wildlife management decision-making in the United States. Using almost 2000 serological samples collected from non-native wild pigs (Sus scrofa) throughout Florida (U.S.), we compared the prevalence and exposure risk of two directly transmitted pathogens, pseudorabies virus (PrV) and Brucella spp., to test the hypothesis that disease emergence would be positively correlated with one of the most basic wildlife management operations: Hunting. The seroprevalence of PrV-Brucella spp. coinfection or PrV alone was higher for wild pigs in land management areas that allowed hunting with dogs than in areas that culled animals using other harvest methods. This pattern did not hold for Brucella alone. The likelihood of exposure to PrV, but not Brucella spp., was also significantly higher among wild pigs at hunted sites than at sites where animals were culled. By failing to consider the impact of dog hunting on the emergence of non-native pathogens, current animal management practices have the potential to affect public health, the commercial livestock industry, and wildlife conservation.
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Affiliation(s)
- Amanda N Carr
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL 32611, USA.
- Present Address: Biology Department, Western Washington University, Bellingham, WA 98225, USA.
| | - Michael P Milleson
- United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, Gainesville, FL 32641, USA.
| | - Felipe A Hernández
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL 32611, USA.
- School of Natural Resources and Environment, University of Florida, Gainesville, FL 32601, USA.
| | - Hunter R Merrill
- Department of Agricultural and Biological Engineering, University of Florida, Gainesville, FL 32603, USA.
| | - Michael L Avery
- United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, Gainesville, FL 32641, USA.
| | - Samantha M Wisely
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL 32611, USA.
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Dallas TA, Krkošek M, Drake JM. Experimental evidence of a pathogen invasion threshold. ROYAL SOCIETY OPEN SCIENCE 2018; 5:171975. [PMID: 29410876 PMCID: PMC5792953 DOI: 10.1098/rsos.171975] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 12/11/2017] [Indexed: 05/15/2023]
Abstract
Host density thresholds to pathogen invasion separate regions of parameter space corresponding to endemic and disease-free states. The host density threshold is a central concept in theoretical epidemiology and a common target of human and wildlife disease control programmes, but there is mixed evidence supporting the existence of thresholds, especially in wildlife populations or for pathogens with complex transmission modes (e.g. environmental transmission). Here, we demonstrate the existence of a host density threshold for an environmentally transmitted pathogen by combining an epidemiological model with a microcosm experiment. Experimental epidemics consisted of replicate populations of naive crustacean zooplankton (Daphnia dentifera) hosts across a range of host densities (20-640 hosts l-1) that were exposed to an environmentally transmitted fungal pathogen (Metschnikowia bicuspidata). Epidemiological model simulations, parametrized independently of the experiment, qualitatively predicted experimental pathogen invasion thresholds. Variability in parameter estimates did not strongly influence outcomes, though systematic changes to key parameters have the potential to shift pathogen invasion thresholds. In summary, we provide one of the first clear experimental demonstrations of pathogen invasion thresholds in a replicated experimental system, and provide evidence that such thresholds may be predictable using independently constructed epidemiological models.
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Affiliation(s)
- Tad A. Dallas
- Department of Environmental Science and Policy, University of California, Davis, CA, USA
- Odum School of Ecology, University of Georgia, Athens, GA, USA
| | - Martin Krkošek
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | - John M. Drake
- Odum School of Ecology, University of Georgia, Athens, GA, USA
- Center for the Ecology of Infectious Disease, University of Georgia, Athens, GA, USA
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Bolzoni L, Bonacini E, Soresina C, Groppi M. Time-optimal control strategies in SIR epidemic models. Math Biosci 2017; 292:86-96. [PMID: 28801246 PMCID: PMC7094293 DOI: 10.1016/j.mbs.2017.07.011] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2016] [Revised: 04/11/2017] [Accepted: 07/14/2017] [Indexed: 11/25/2022]
Abstract
We investigate the time-optimal control problem in SIR (Susceptible-Infected-Recovered) epidemic models, focusing on different control policies: vaccination, isolation, culling, and reduction of transmission. Applying the Pontryagin's Minimum Principle (PMP) to the unconstrained control problems (i.e. without costs of control or resource limitations), we prove that, for all the policies investigated, only bang-bang controls with at most one switch are admitted. When a switch occurs, the optimal strategy is to delay the control action some amount of time and then apply the control at the maximum rate for the remainder of the outbreak. This result is in contrast with previous findings on the unconstrained problems of minimizing the total infectious burden over an outbreak, where the optimal strategy is to use the maximal control for the entire epidemic. Then, the critical consequence of our results is that, in a wide range of epidemiological circumstances, it may be impossible to minimize the total infectious burden while minimizing the epidemic duration, and vice versa. Moreover, numerical simulations highlighted additional unexpected results, showing that the optimal control can be delayed also when the control reproduction number is lower than one and that the switching time from no control to maximum control can even occur after the peak of infection has been reached. Our results are especially important for livestock diseases where the minimization of outbreaks duration is a priority due to sanitary restrictions imposed to farms during ongoing epidemics, such as animal movements and export bans.
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Affiliation(s)
- Luca Bolzoni
- Risk Analysis Unit, Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, Via dei Mercati 13, Parma 43126, Italy.
| | - Elena Bonacini
- Department of Mathematics and Computer Science, University of Parma, Parco Area delle Scienze 53/A, Parma 43124, Italy
| | - Cinzia Soresina
- Department of Mathematics "F. Enriques", University of Milano, Via C. Saldini 50, Milano 20133, Italy
| | - Maria Groppi
- Department of Mathematics and Computer Science, University of Parma, Parco Area delle Scienze 53/A, Parma 43124, Italy
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Van Allen BG, Dillemuth FP, Flick AJ, Faldyn MJ, Clark DR, Rudolf VHW, Elderd BD. Cannibalism and Infectious Disease: Friends or Foes? Am Nat 2017; 190:299-312. [PMID: 28829639 DOI: 10.1086/692734] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Cannibalism occurs in a majority of both carnivorous and noncarnivorous animal taxa from invertebrates to mammals. Similarly, infectious parasites are ubiquitous in nature. Thus, interactions between cannibalism and disease occur regularly. While some adaptive benefits of cannibalism are clear, the prevailing view is that the risk of parasite transmission due to cannibalism would increase disease spread and, thus, limit the evolutionary extent of cannibalism throughout the animal kingdom. In contrast, surprisingly little attention has been paid to the other half of the interaction between cannibalism and disease, that is, how cannibalism affects parasites. Here we examine the interaction between cannibalism and parasites and show how advances across independent lines of research suggest that cannibalism can also reduce the prevalence of parasites and, thus, infection risk for cannibals. Cannibalism does this by both directly killing parasites in infected victims and by reducing the number of susceptible hosts, often enhanced by the stage-structured nature of cannibalism and infection. While the well-established view that disease should limit cannibalism has held sway, we present theory and examples from a synthesis of the literature showing how cannibalism may also limit disease and highlight key areas where conceptual and empirical work is needed to resolve this debate.
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Samuel MD, Storm DJ. Chronic wasting disease in white-tailed deer: infection, mortality, and implications for heterogeneous transmission. Ecology 2016; 97:3195-3205. [PMID: 27870037 DOI: 10.1002/ecy.1538] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 06/29/2016] [Accepted: 07/05/2016] [Indexed: 11/08/2022]
Abstract
Chronic wasting disease (CWD) is a fatal neurodegenerative disease affecting free-ranging and captive cervids that now occurs in 24 U.S. states and two Canadian provinces. Despite the potential threat of CWD to deer populations, little is known about the rates of infection and mortality caused by this disease. We used epidemiological models to estimate the force of infection and disease-associated mortality for white-tailed deer in the Wisconsin and Illinois CWD outbreaks. Models were based on age-prevalence data corrected for bias in aging deer using the tooth wear and replacement method. Both male and female deer in the Illinois outbreak had higher corrected age-specific prevalence with slightly higher female infection than deer in the Wisconsin outbreak. Corrected ages produced more complex models with different infection and mortality parameters than those based on apparent prevalence. We found that adult male deer have a more than threefold higher risk of CWD infection than female deer. Males also had higher disease mortality than female deer. As a result, CWD prevalence was twofold higher in adult males than females. We also evaluated the potential impacts of alternative contact structures on transmission dynamics in Wisconsin deer. Results suggested that transmission of CWD among male deer during the nonbreeding season may be a potential mechanism for producing higher rates of infection and prevalence characteristically found in males. However, alternatives based on high environmental transmission and transmission from females to males during the breeding season may also play a role.
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Affiliation(s)
- Michael D Samuel
- U.S. Geological Survey, Wisconsin Cooperative Wildlife Research Unit, University of Wisconsin , Madison, Wisconsin, 53706, USA
| | - Daniel J Storm
- Department of Forest and Wildlife Ecology, University of Wisconsin , Madison, Wisconsin, 53706, USA.,Wisconsin Department of Natural Resources, Rhinelander, Wisconsin, 54501, USA
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26
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Tosa MI, Schauber EM, Nielsen CK. Localized removal affects white-tailed deer space use and contacts. J Wildl Manage 2016. [DOI: 10.1002/jwmg.21176] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Marie I. Tosa
- Cooperative Wildlife Research Laboratory, Department of Zoology; Center for Ecology, Southern Illinois University; 1125 Lincoln Drive Carbondale IL USA
| | - Eric M. Schauber
- Cooperative Wildlife Research Laboratory, Department of Zoology; Center for Ecology, Southern Illinois University; 1125 Lincoln Drive Carbondale IL USA
| | - Clayton K. Nielsen
- Cooperative Wildlife Research Laboratory, Department of Forestry; Southern Illinois University; 1125 Lincoln Drive Carbondale IL USA
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Uehlinger FD, Johnston AC, Bollinger TK, Waldner CL. Systematic review of management strategies to control chronic wasting disease in wild deer populations in North America. BMC Vet Res 2016; 12:173. [PMID: 27549119 PMCID: PMC4994292 DOI: 10.1186/s12917-016-0804-7] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Accepted: 08/18/2016] [Indexed: 01/01/2023] Open
Abstract
Background Chronic wasting disease (CWD) is a contagious, fatal prion disease affecting cervids in a growing number of regions across North America. Projected deer population declines and concern about potential spread of CWD to other species warrant strategies to manage this disease. Control efforts to date have been largely unsuccessful, resulting in continuing spread and increasing prevalence. This systematic review summarizes peer-reviewed published reports describing field-applicable CWD control strategies in wild deer populations in North America using systematic review methods. Ten databases were searched for peer-reviewed literature. Following deduplication, relevance screening, full-text appraisal, subject matter expert review and qualitative data extraction, nine references were included describing four distinct management strategies. Results Six of the nine studies used predictive modeling to evaluate control strategies. All six demonstrated one or more interventions to be effective but results were dependant on parameters and assumptions used in the model. Three found preferential removal of CWD infected deer to be effective in reducing CWD prevalence; one model evaluated a test and slaughter strategy, the other selective removal of infected deer by predators and the third evaluated increased harvest of the sex with highest prevalence (males). Three models evaluated non-selective harvest of deer. There were only three reports that examined primary data collected as part of observational studies. Two of these studies supported the effectiveness of intensive non-selective culling; the third study did not find a difference between areas that were subjected to culling and those that were not. Seven of the nine studies were conducted in the United States. Conclusions This review highlights the paucity of evaluated, field-applicable control strategies for CWD in wild deer populations. Knowledge gaps in the complex epidemiology of CWD and the intricacies inherent to prion diseases currently pose significant challenges to effective control of this disease in wild deer in North America. Electronic supplementary material The online version of this article (doi:10.1186/s12917-016-0804-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- F D Uehlinger
- Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, S7N 5B4, Canada.
| | - A C Johnston
- Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, S7N 5B4, Canada
| | - T K Bollinger
- Canadian Wildlife Health Cooperative, Department of Veterinary Pathology, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, S7N 5B4, Canada
| | - C L Waldner
- Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, S7N 5B4, Canada
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Abstract
Infectious disease dynamics are determined, to a great extent, by the social structure of the host. We evaluated sociality, or the tendency to form groups, in Rocky Mountain mule deer (Odocoileus hemionus hemionus) from a chronic wasting disease (CWD) endemic area in Saskatchewan, Canada, to better understand factors that may affect disease transmission. Using group size data collected on 365 radio-collared mule deer (2008–2013), we built a generalized linear mixed model (GLMM) to evaluate whether factors such as CWD status, season, habitat and time of day, predicted group occurrence. Then, we built another GLMM to determine factors associated with group size. Finally, we used 3 measures of group size (typical, mean and median group sizes) to quantify levels of sociality. We found that mule deer showing clinical signs of CWD were less likely to be reported in groups than clinically healthy deer after accounting for time of day, habitat, and month of observation. Mule deer groups were much more likely to occur in February and March than in July. Mixed-sex groups in early gestation were larger than any other group type in any season. Groups were largest and most likely to occur at dawn and dusk, and in open habitats, such as cropland. We discuss the implication of these results with respect to sociobiology and CWD transmission dynamics.
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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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Ben-Horin T, Lafferty KD, Bidegain G, Lenihan HS. Fishing diseased abalone to promote yield and conservation. Philos Trans R Soc Lond B Biol Sci 2016; 371:20150211. [PMID: 26880843 PMCID: PMC4760141 DOI: 10.1098/rstb.2015.0211] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/28/2015] [Indexed: 12/27/2022] Open
Abstract
Past theoretical models suggest fishing disease-impacted stocks can reduce parasite transmission, but this is a good management strategy only when the exploitation required to reduce transmission does not overfish the stock. We applied this concept to a red abalone fishery so impacted by an infectious disease (withering syndrome) that stock densities plummeted and managers closed the fishery. In addition to the non-selective fishing strategy considered by past disease-fishing models, we modelled targeting (culling) infected individuals, which is plausible in red abalone because modern diagnostic tools can determine infection without harming landed abalone and the diagnostic cost is minor relative to the catch value. The non-selective abalone fishing required to eradicate parasites exceeded thresholds for abalone sustainability, but targeting infected abalone allowed the fishery to generate yield and reduce parasite prevalence while maintaining stock densities at or above the densities attainable if the population was closed to fishing. The effect was strong enough that stock and yield increased even when the catch was one-third uninfected abalone. These results could apply to other fisheries as the diagnostic costs decline relative to catch value.
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Affiliation(s)
- Tal Ben-Horin
- College of the Environment and Life Sciences, University of Rhode Island, Kingston, RI 02881, USA Haskin Shellfish Research Laboratory, Rutgers University, Port Norris, NJ 08349, USA
| | - Kevin D Lafferty
- US Geological Survey, Western Ecological Research Center, c/o Marine Science Institute, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Gorka Bidegain
- Gulf Coast Research Laboratory, University of Southern Mississippi, Ocean Springs, MS 39564, USA
| | - Hunter S Lenihan
- Bren School of Environmental Science and Management, University of California Santa Barbara, Santa Barbara, CA 93106, USA
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31
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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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Intra-specific competition in predator can promote the coexistence of an eco-epidemiological model with strong Allee effects in prey. Biosystems 2015; 137:34-44. [DOI: 10.1016/j.biosystems.2015.09.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 09/04/2015] [Accepted: 09/08/2015] [Indexed: 11/22/2022]
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Potapov A, Merrill E, Pybus M, Lewis MA. Empirical Estimation of R0 for Unknown Transmission Functions: The Case of Chronic Wasting Disease in Alberta. PLoS One 2015; 10:e0140024. [PMID: 26452231 PMCID: PMC4599850 DOI: 10.1371/journal.pone.0140024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2013] [Accepted: 09/20/2015] [Indexed: 11/23/2022] Open
Abstract
We consider the problem of estimating the basic reproduction number R0 from data on prevalence dynamics at the beginning of a disease outbreak. We derive discrete and continuous time models, some coefficients of which are to be fitted from data. We show that prevalence of the disease is sufficient to determine R0. We apply this method to chronic wasting disease spread in Alberta determining a range of possible R0 and their sensitivity to the probability of deer annual survival.
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Affiliation(s)
- Alex Potapov
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2G1, Canada
- Centre for Mathematical Biology, University of Alberta, Edmonton, AB, T6G 2G1, Canada
- Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, AB, T6G 2G1, Canada
- * E-mail:
| | - Evelyn Merrill
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2G1, Canada
| | - Margo Pybus
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2G1, Canada
- Alberta Sustainable Resource Development, 6909–116 St., Edmonton, AB, T6H 4P2, Canada
| | - Mark A. Lewis
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2G1, Canada
- Centre for Mathematical Biology, University of Alberta, Edmonton, AB, T6G 2G1, Canada
- Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, AB, T6G 2G1, Canada
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Familiarity breeds contempt: combining proximity loggers and GPS reveals female white-tailed deer (Odocoileus virginianus) avoiding close contact with neighbors. J Wildl Dis 2015; 51:79-88. [PMID: 25398000 DOI: 10.7589/2013-06-139] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Social interactions can influence infectious disease dynamics, particularly for directly transmitted pathogens. Therefore, reliable information on contact frequency within and among groups can better inform disease modeling and management. We compared three methods of assessing contact patterns: (1) space-use overlap (volume of interaction [VI]), (2) direct contact rates measured by simultaneous global positioning system (GPS) locations (<10 m apart), and (3) direct contact rates measured by proximity loggers (PLs; 1-m detection) among female white-tailed deer (Odocoileus virginianus). We calculated the PL∶GPS contact ratios to see whether both devices reveal similar contact patterns and thus predict similar pathogen transmission patterns. Contact rates measured by GPS and PLs were similarly high for two within-group dyads (pairs of deer in the same social groups). Dyads representing separate but neighboring groups (high VI) had PL∶GPS contact ratios near zero, whereas dyads further apart (intermediate VI) had higher PL∶GPS contact ratios. Social networks based on PL contacts showed the fewest connected individuals and lowest mean centrality measures; network metrics were intermediate when based on GPS contacts and greatest when based on VI. Thus, the VI network portrayed animals to be more uniformly and strongly connected than did the PL network. We conclude that simultaneous GPS locations, compared with PLs, substantially underestimate the impact of group membership on direct contact rates of female deer and make networks appear more connected. We also present evidence that deer coming within the general vicinity of each other are less likely to come in close contact if they are in neighboring social groups than deer whose home ranges overlap little if at all. Combined, these results provide evidence that direct transmission of disease agents among female and juvenile white-tailed deer is likely to be constrained both spatially and by social structure, more so than GPS data alone would suggest.
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Sapsford SJ, Voordouw MJ, Alford RA, Schwarzkopf L. Infection dynamics in frog populations with different histories of decline caused by a deadly disease. Oecologia 2015; 179:1099-110. [PMID: 26293680 DOI: 10.1007/s00442-015-3422-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 08/07/2015] [Indexed: 10/23/2022]
Abstract
Pathogens can drive host population dynamics. Chytridiomycosis is a fungal disease of amphibians that is caused by the fungus Batrachochytrium dendrobatidis (Bd). This pathogen has caused declines and extinctions in some host species whereas other host species coexist with Bd without suffering declines. In the early 1990s, Bd extirpated populations of the endangered common mistfrog, Litoria rheocola, at high-elevation sites, while populations of the species persisted at low-elevation sites. Today, populations have reappeared at many high-elevation sites where they presently co-exist with the fungus. We conducted a capture-mark-recapture (CMR) study of six populations of L. rheocola over 1 year, at high and low elevations. We used multistate CMR models to determine which factors (Bd infection status, site type, and season) influenced rates of frog survival, recapture, infection, and recovery from infection. We observed Bd-induced mortality of individual frogs, but did not find any significant effect of Bd infection on the survival rate of L. rheocola at the population level. Survival and recapture rates depended on site type and season. Infection rate was highest in winter when temperatures were favourable for pathogen growth, and differed among site types. The recovery rate was high (75.7-85.8%) across seasons, and did not differ among site types. The coexistence of L. rheocola with Bd suggests that (1) frog populations are becoming resistant to the fungus, (2) Bd may have evolved lower virulence, or (3) current environmental conditions may be inhibiting outbreaks of the fatal disease.
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Affiliation(s)
- Sarah J Sapsford
- School of Marine and Tropical Biology, James Cook University, Townsville, Australia. .,School of Veterinary and Life Sciences, Murdoch University, Perth, Australia.
| | | | - Ross A Alford
- School of Marine and Tropical Biology, James Cook University, Townsville, Australia
| | - Lin Schwarzkopf
- School of Marine and Tropical Biology, James Cook University, Townsville, Australia
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Abstract
Modelling wildlife disease poses some unique challenges. Wildlife disease systems are data poor in comparison with human or livestock disease systems, and the impact of disease on population size is often the key question of interest. This review concentrates specifically on the application of dynamic models to evaluate and guide management strategies. Models have proved useful particularly in two areas. They have been widely used to evaluate vaccination strategies, both for protecting endangered species and for preventing spillover from wildlife to humans or livestock. They have also been extensively used to evaluate culling strategies, again both for diseases in species of conservation interest and to prevent spillover. In addition, models are important to evaluate the potential of parasites and pathogens as biological control agents. The review concludes by identifying some key research gaps, which are further development of models of macroparasites, deciding on appropriate levels of complexity, modelling genetic management and connecting models to data.
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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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Peel AJ, Pulliam JRC, Luis AD, Plowright RK, O'Shea TJ, Hayman DTS, Wood JLN, Webb CT, Restif O. The effect of seasonal birth pulses on pathogen persistence in wild mammal populations. Proc Biol Sci 2015; 281:rspb.2013.2962. [PMID: 24827436 PMCID: PMC4046395 DOI: 10.1098/rspb.2013.2962] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The notion of a critical community size (CCS), or population size that is likely to result in long-term persistence of a communicable disease, has been developed based on the empirical observations of acute immunizing infections in human populations, and extended for use in wildlife populations. Seasonal birth pulses are frequently observed in wildlife and are expected to impact infection dynamics, yet their effect on pathogen persistence and CCS have not been considered. To investigate this issue theoretically, we use stochastic epidemiological models to ask how host life-history traits and infection parameters interact to determine pathogen persistence within a closed population. We fit seasonal birth pulse models to data from diverse mammalian species in order to identify realistic parameter ranges. When varying the synchrony of the birth pulse with all other parameters being constant, our model predicted that the CCS can vary by more than two orders of magnitude. Tighter birth pulses tended to drive pathogen extinction by creating large amplitude oscillations in prevalence, especially with high demographic turnover and short infectious periods. Parameters affecting the relative timing of the epidemic and birth pulse peaks determined the intensity and direction of the effect of pre-existing immunity in the population on the pathogen's ability to persist beyond the initial epidemic following its introduction.
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Affiliation(s)
- A J Peel
- Disease Dynamics Unit, Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, UK Institute of Zoology, Zoological Society of London, Regent's Park, London NW1 4RY, UK Environmental Futures Research Institute, Griffith University, Brisbane, 4111, Australia
| | - J R C Pulliam
- Fogarty International Center, National Institutes of Health, Bethesda, MD 20892, USA Department of Biology, University of Florida, Gainesville, FL 32611, USA Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610, USA
| | - A D Luis
- Fogarty International Center, National Institutes of Health, Bethesda, MD 20892, USA Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - R K Plowright
- Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA 16802, USA
| | - T J O'Shea
- US Geological Survey (retired), PO Box 65, Glen Haven, CO 80532, USA
| | - D T S Hayman
- Fogarty International Center, National Institutes of Health, Bethesda, MD 20892, USA Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - J L N Wood
- Disease Dynamics Unit, Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, UK
| | - C T Webb
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - O Restif
- Disease Dynamics Unit, Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, UK
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40
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Gortazar C, Diez-Delgado I, Barasona JA, Vicente J, De La Fuente J, Boadella M. The Wild Side of Disease Control at the Wildlife-Livestock-Human Interface: A Review. Front Vet Sci 2015; 1:27. [PMID: 26664926 PMCID: PMC4668863 DOI: 10.3389/fvets.2014.00027] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2014] [Accepted: 12/02/2014] [Indexed: 11/30/2022] Open
Abstract
The control of diseases shared with wildlife requires the development of strategies that will reduce pathogen transmission between wildlife and both domestic animals and human beings. This review describes and criticizes the options currently applied and attempts to forecast wildlife disease control in the coming decades. Establishing a proper surveillance and monitoring scheme (disease and population wise) is the absolute priority before even making the decision as to whether or not to intervene. Disease control can be achieved by different means, including: (1) preventive actions, (2) arthropod vector control, (3) host population control through random or selective culling, habitat management or reproductive control, and (4) vaccination. The alternative options of zoning or no-action should also be considered, particularly in view of a cost/benefit assessment. Ideally, tools from several fields should be combined in an integrated control strategy. The success of disease control in wildlife depends on many factors, including disease ecology, natural history, and the characteristics of the pathogen, the availability of suitable diagnostic tools, the characteristics of the domestic and wildlife host(s) and vectors, the geographical spread of the problem, the scale of the control effort and stakeholders’ attitudes.
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Affiliation(s)
- Christian Gortazar
- SaBio (Health and Biotechnology), IREC (CSIC - UCLM - JCCM) , Ciudad Real , Spain
| | - Iratxe Diez-Delgado
- SaBio (Health and Biotechnology), IREC (CSIC - UCLM - JCCM) , Ciudad Real , Spain ; Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid , Madrid , Spain
| | - Jose Angel Barasona
- SaBio (Health and Biotechnology), IREC (CSIC - UCLM - JCCM) , Ciudad Real , Spain
| | - Joaquin Vicente
- SaBio (Health and Biotechnology), IREC (CSIC - UCLM - JCCM) , Ciudad Real , Spain
| | - Jose De La Fuente
- SaBio (Health and Biotechnology), IREC (CSIC - UCLM - JCCM) , Ciudad Real , Spain ; Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University , Stillwater, OK , USA
| | - Mariana Boadella
- SABIOtec Spin-Off, Edificio Polivalente UCLM , Ciudad Real , Spain
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41
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Heard GW, Scroggie MP, Clemann N, Ramsey DSL. Wetland characteristics influence disease risk for a threatened amphibian. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2014; 24:650-662. [PMID: 24988766 DOI: 10.1890/13-0389.1] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Identifying determinants of the probability and intensity of infections is important for understanding the epidemiology of wildlife diseases, and for managing their impact on threatened species. Chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis, has decimated populations of some amphibians. However, recent studies have identified important environmental constraints on the disease, related to the pathogen's physiological tolerances. In this study, we identified several intrinsic and extrinsic determinants of the probability and intensity of chytrid infections for the threatened growling grass frog (Litoria raniformis) in southeastern Australia, and used mark-recapture to estimate the effect of chytrid infections on the probability of survival of these frogs. Water temperature and salinity had negative effects on both the probability and intensity of chytrid infections. We coupled models of the infection process with a model of the effect of chytrid infections on the probability of survival to assess variation in the impact of chytridiomycosis between wetlands with differing temperature and salinity profiles. Our results suggest that warm, saline wetlands may be refuges from chytridiomycosis for L. raniformis, and should be priorities for protection. Our results also suggest that management actions that increase water temperature (e.g., reducing canopy shading) and salinity (e.g., complementing inflows with groundwater) could be trialed to reduce the impacts of chytridiomycosis on this species. This and other recent studies highlight the value of research on environmental risk factors for chytridiomycosis.
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42
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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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43
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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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44
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Kang Y, Castillo-Chavez C. Dynamics of SI models with both horizontal and vertical transmissions as well as Allee effects. Math Biosci 2014; 248:97-116. [PMID: 24389426 PMCID: PMC4091922 DOI: 10.1016/j.mbs.2013.12.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 12/11/2013] [Accepted: 12/13/2013] [Indexed: 12/01/2022]
Abstract
A general SI (Susceptible-Infected) epidemic system of host-parasite interactions operating under Allee effects, horizontal and/or vertical transmission, and where infected individuals experience pathogen-induced reductions in reproductive ability, is introduced. The initial focus of this study is on the analyses of the dynamics of density-dependent and frequency-dependent effects on SI models (SI-DD and SI-FD). The analyses identify conditions involving horizontal and vertical transmitted reproductive numbers, namely those used to characterize and contrast SI-FD and SI-DD dynamics. Conditions that lead to disease-driven extinction, or disease-free dynamics, or susceptible-free dynamics, or endemic disease patterns are identified. The SI-DD system supports richer dynamics including limit cycles while the SI-FD model only supports equilibrium dynamics. SI models under "small" horizontal transmission rates may result in disease-free dynamics. SI models under with and inefficient reproductive infectious class may lead to disease-driven extinction scenarios. The SI-DD model supports stable periodic solutions that emerge from an unstable equilibrium provided that either the Allee threshold and/or the disease transmission rate is large; or when the disease has limited influence on the infectives growth rate; and/or when disease-induced mortality is low. Host-parasite systems where diffusion or migration of local populations manage to destabilize them are examples of what is known as diffusive instability. The exploration of SI-dynamics in the presence of dispersal brings up the question of whether or not diffusive instability is a possible outcome. Here, we briefly look at such possibility within two-patch coupled SI-DD and SI-FD systems. It is shown that relative high levels of asymmetry, two modes of transmission, frequency dependence, and Allee effects are capable of supporting diffusive instability.
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Affiliation(s)
- Yun Kang
- Science and Mathematics Faculty, School of Letters and Sciences, Arizona State University, Mesa, AZ 85212, USA.
| | - Carlos Castillo-Chavez
- Mathematical, Computational and Modeling Sciences Center, Arizona State University, Tempe, AZ 85287-1904, USA; School of Human Evolution and Social Changes, Santa Fe Institute, Santa Fe, NM 87501, USA; School of Sustainability, Santa Fe Institute, Santa Fe, NM 87501, USA; Cornell University, Biological Statistics and Computational Biology, Ithaca, NY 14853-2601, USA; Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, 77 MASS Ave. 33-404, Cambridge, MA 02139-4307, USA.
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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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46
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An eco-epidemiological system with infected prey and predator subject to the weak Allee effect. Math Biosci 2013. [DOI: 10.1016/j.mbs.2013.10.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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47
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Bolzoni L, Tessoni V, Groppi M, De Leo GA. React or wait: which optimal culling strategy to control infectious diseases in wildlife. J Math Biol 2013; 69:1001-25. [PMID: 24057080 DOI: 10.1007/s00285-013-0726-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 08/23/2013] [Indexed: 11/26/2022]
Abstract
We applied optimal control theory to an SI epidemic model to identify optimal culling strategies for diseases management in wildlife. We focused on different forms of the objective function, including linear control, quadratic control, and control with limited amount of resources. Moreover, we identified optimal solutions under different assumptions on disease-free host dynamics, namely: self-regulating logistic growth, Malthusian growth, and the case of negligible demography. We showed that the correct characterization of the disease-free host growth is crucial for defining optimal disease control strategies. By analytical investigations of the model with negligible demography, we demonstrated that the optimal strategy for the linear control can be either to cull at the maximum rate at the very beginning of the epidemic (reactive culling) when the culling cost is low, or never to cull, when culling cost is high. On the other hand, in the cases of quadratic control or limited resources, we demonstrated that the optimal strategy is always reactive. Numerical analyses for hosts with logistic growth showed that, in the case of linear control, the optimal strategy is always reactive when culling cost is low. In contrast, if the culling cost is high, the optimal strategy is to delay control, i.e. not to cull at the onset of the epidemic. Finally, we showed that for diseases with the same basic reproduction number delayed control can be optimal for acute infections, i.e. characterized by high disease-induced mortality and fast dynamics, while reactive control can be optimal for chronic ones.
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Affiliation(s)
- Luca Bolzoni
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, Via dei Mercati 13, 43100 , Parma, Italy,
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48
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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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Evaluation of a wild white-tailed deer population management program for controlling chronic wasting disease in Illinois, 2003–2008. Prev Vet Med 2013; 110:541-8. [DOI: 10.1016/j.prevetmed.2013.03.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 03/05/2013] [Accepted: 03/07/2013] [Indexed: 12/11/2022]
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