Consensus Study Report
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This activity was supported by a contract between the National Academy of Sciences and U.S. Geological Survey (Contract No. AWD-008148). Any opinions, findings, conclusions, or recommendations expressed in this publication do not necessarily reflect the views of any organization or agency that provided support for the project.
International Standard Book Number-13: 978-0-309-71478-5
International Standard Book Number-10: 0-309-71478-8
Digital Object Identifier: https://doi.org/10.17226/27449
Library of Congress Control Number: 2025935989
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Suggested citation: National Academies of Sciences, Engineering, and Medicine. 2025. State of Knowledge Regarding Transmission, Spread, and Management of Chronic Wasting Disease in U.S. Captive and Free-Ranging Cervid Populations. Washington, DC: The National Academies Press. https://doi.org/10.17226/27449.
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COMMITTEE ON THE REVIEW OF TRANSMISSION AND GEOGRAPHIC SPREAD OF CHRONIC WASTING DISEASE IN U.S. CERVID POPULATIONS
LONNIE KING (Chair), The Ohio State University College of Veterinary Medicine
SONJA A. CHRISTENSEN, Michigan State University
MATTHEW CHARLES DUNFEE, Wildlife Management Institute
DAVID C. FINNOFF, University of Wyoming
THOMAS GIDLEWSKI, U.S. Department of Agriculture (Retired)
NICHOLAS J. HALEY, Midwestern University
DEBBIE McKENZIE, University of Alberta Department of Biological Sciences
MICHAEL W. MILLER, Colorado Division of Parks and Wildlife (Retired)
RODRIGO MORALES, The University of Texas Health Science Center at Houston and Universidad Bernardo O’Higgins
MARGO J. PYBUS, Alberta Fish and Wildlife
TIFFANY MARIE WOLF, University of Minnesota College of Veterinary Medicine
Study Staff
SAMMANTHA MAGSINO, Responsible Staff Officer/Senior Program Officer
SUSANA RODRIGUEZ, Program Officer
MITCHELL HEBNER, Research Associate (since May 2024)
MALIA BROWN, Program Assistant
ROBIN SCHOEN, Board Director
BOARD ON AGRICULTURE AND NATURAL RESOURCES
JILL J. McCLUSKEY (Chair), Washington State University
AMY W. ANDO, University of Illinois, Urbana-Champaign
ARISTOS ARISTIDOU,1 Biomason, Inc.
BRUNO BASSO, Michigan State University, East Lansing
BERNADETTE M. DUNHAM, George Washington University
JESSICA E. HALOFSKY, U.S. Department of Agriculture
ERMIAS KEBREAB, University of California, Davis
MARTY D. MATLOCK, University of Arkansas
JOHN P. McNAMARA, Washington State University
NAIMA MOUSTAID-MOUSSA, Texas Tech University
V. ALARIC SAMPLE, George Mason University
ROGER E. WYSE, Spruce Capital Partners
Staff
ROBIN SCHOEN, Director
MALIA BROWN, Senior Program Assistant
CAMILLA YANDOC ABLES, Senior Program Officer
MITCHELL HEBNER, Research Associate
KARA N. LANEY, Senior Program Officer
CYNTHIA GETNER, Senior Finance Business Partner
ALBARAA SARSOUR, Program Officer
SAMANTHA SISANACHANDENG, Senior Program Assistant
___________________
1 Member of the National Academy of Engineering.
BOARD ON ANIMAL HEALTH SCIENCES, CONSERVATION, AND RESEARCH
ROBERT C. DYSKO (Co-Chair), University of Michigan
BARBARA J. NATTERSON-HOROWITZ (Co-Chair), University of California
SONNET S. JONKER, Oregon Health & Science University
ANNE MAGLIA, University of Massachusetts
SUZAN MURRAY, Smithsonian Conservation Biology Institute, National Zoological Park
GUY H. PALMER,1 Washington State University
CHRISTINE A. PETERSEN, The Ohio State University
ROSALIND ROLLAND, The New England Aquarium
CAROLINE ZEISS, Yale School of Medicine
Staff
KAVITA BERGER, Co-Director
ROBIN SCHOEN, Co-Director
JEANNE AQUILINO, Senior Finance Business Partner
MITCHELL HEBNER, Research Associate
NIA JOHNSON, Senior Program Officer
SUSANA RODRIGUEZ, Program Officer
MARIAH WAUL, Senior Program Assistant
___________________
1 Member of the National Academy of Medicine.
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Reviewers
This Consensus Study Report was reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise. The purpose of this independent review is to provide candid and critical comments that will assist the National Academies of Sciences, Engineering, and Medicine in making each published report as sound as possible and to ensure that it meets the institutional standards for quality, objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process.
We thank the following individuals for their review of this report:
EYAL FRANK, University of Chicago Harris School of Public Policy
DAVIN HENDERSON, CWD Evolution
ANNE JUSTICE-ALLEN, Arizona Game and Fish Department
ELIZABETH KELLOGG, Donald Danforth Plant Science Center
DARLENE KONKLE, Wisconsin State
KERSTIN LINDBLAD-TOH, The Broad Institute
RYAN MADDOX, National Center for Emerging and Zoonotic Infectious Diseases
DIANE MANN-KLAGER, Bureau of Indian Affairs
CHRISTOPHER SEABURY, Texas A&M University
CLIFFORD SHIPLEY, University of Illinois (Retired)
MARGARET WILD, Washington State University
GLEN ZEBARTH, Oak Point Elk Farm, Minnesota Elk Breeders Association
Although the reviewers listed above provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations of this report, nor did they see the final draft before its release. The review of this report was overseen by TERRY McELWAIN (NAM), Washington State University, and MICHAEL LAIRMORE (NAM), University of California, Davis. They were responsible for making certain that an independent examination of this report was carried out in accordance with the standards of the National Academies and that all review comments were carefully considered. Responsibility for the final content rests entirely with the authoring committee and the National Academies.
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Acknowledgments
There were many helpful and dedicated people involved in developing and completing this report. The committee wishes to express its thanks and appreciation to the individuals and organizations who gave their valuable time to provide information and advice to us through their participation, sharing valuable research and practice findings and helpful insights. The committee is also indebted to a talented and hard-working staff who contributed immeasurably to the planning and execution of meetings and especially to the production of this report. We gratefully acknowledge the efforts of Senior Program Officer Sammantha Magsino, Program Officer Susana Rodriguez, Program Assistant Malia Brown, and Director for the Board on Agriculture and Natural Resources Robin Schoen for their dedication to this project and their indispensable support and encouragement. The committee also extends its sincere thanks to the internal and external reviewers for their thoughtful and helpful feedback and invaluable insights that enabled us to improve the report.
The committee wishes to recognize the sponsors from the U.S. Fish and Wildlife Service and U.S. Geological Survey of the U.S. Department of the Interior, and the Animal and Plant Health Inspection Service of the U.S. Department of Agriculture who supported and helped to direct the report’s organization and statement of task. The committee sincerely hopes that our efforts will help guide and encourage their critical plans and programs for the future. Finally, as chair, I am especially grateful and wish to express my deepest appreciation for the talented team who served as committee members and for their passion and determination to successfully address chronic wasting disease. Although a difficult task, these members were steadfast in their commitment, embraced teamwork and collaboration, and openly and freely shared their diverse experiences and exceptional expertise.
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Preface
The physicist, Stephen Hawking, once said, “I think the next century (21st) will be the century of complexity.” His prediction has become a reality, and the term complexity also describes our world of infectious diseases today. Chronic wasting disease (CWD) is an example of a complex disease. It is perplexing and multifaceted and involves multiple species of the family Cervidae (i.e., the deer family). It is influenced by numerous factors and drivers, and it continues to evolve at the interface of natural and human systems.
Although first observed as a syndrome in Colorado in 1967 and first reported as a disease in 1980, CWD is likely to have been present for some time prior to this initial observation. Over the last few decades, there has been a significant increase in the number of cases being diagnosed, and the disease has been found in much larger geographic areas across the United States. CWD is both an endemic and epidemic disease and may be slowly progressing or rapidly increasing in some endemic settings. CWD represents a substantial threat to both captive and free-ranging cervids.
Considering this context, the U.S. Fish and Wildlife Service and the U.S. Geological Survey of the U.S. Department of the Interior, and the Animal and Plant Health Inspection Service of the U.S. Department of Agriculture invited the National Academies of Sciences, Engineering, and Medicine to form an expert committee and to conduct an in-depth scientific review of the state of knowledge of CWD in the United States. They also requested that this committee draw conclusions about the transmission, dissemination, and effectiveness of interventions to control the disease in both captive herds and free-ranging cervid populations. This statement of task defined the scope of this report and established its purpose. These government agencies were designated as sponsors for the report based on congressional language found in America’s Conservation Enhancement Act (ACE). The goal of the committee was to create a report that addresses these points based on a review of published and ongoing research and by engaging other experts through a series of public meetings. The report has been written to help policymakers, government officials, and the lay public to better understand the many dimensions of CWD. The report will also be shared with interested congressional committees, government agencies, and members of a national CWD Task Force (also designated by ACE) to be formed in the near future.
The committee put together a comprehensive picture of the state of knowledge for CWD including an analysis of the pathogenesis, transmission, dissemination, epidemiology, diagnostics, drivers, control strategies, and human dimensions describing CWD. In reviewing this content, a common and consistent finding emerged in the analyses; a large body of knowledge regarding CWD has been generated in recent decades, but there is also a lack of knowledge and multiple information gaps pertaining to many aspects of the disease. While the committee acknowledges and appreciates the productive work of researchers and practitioners, the state of knowledge is still
significantly limited, and the consequence has created much uncertainty about CWD. The lack of evidenced-based information has greatly constrained our understanding of the disease and has created a barrier to both quantify its impact and measure the effectiveness of current interventions to prevent and control it. Adding to the complexity of CWD is the need to manage and accommodate different and often conflicting views, perspectives, and cultures of multiple interest groups who are affected by or are themselves affecting the status of CWD. This consensus report contains findings and offers key conclusions about the state of knowledge of CWD, but it purposely does not contain specific recommendations. Instead, it provides critical results to inform officials working to control CWD and to serve as a foundation for the proposed CWD Task Force to begin its deliberations.
Even with current attempts to limit and control the disease, new cases are being identified and are being found in new geographic sites in both captive and free-ranging cervids at an alarming rate. The capacity and dedicated resources to combat CWD do not seem to be commensurate with the serious consequences of the threat. The disease, simply, is too important to ignore. The many existing critical knowledge gaps need to be filled; new interventions are badly needed; a clarity of purpose and the collaboration and coordination of activities among many interest groups are essential; and a new sense of urgency seems obvious. Although CWD is challenging, especially with the current deficiencies in our state of knowledge and its inherent complexity, this reality should not prevent critical actions. Not taking CWD seriously or failing to enact effective interventions will likely make the disease more expensive to address in the future and potentially more intractable, if not impossible, to prevent or control in many areas. However, the adoption and proper implementation of existing strategies, albeit imperfect, can still limit and reduce the transmission and progression of CWD. It is the hope of the committee that this report will raise the awareness of CWD and serve as an incentive to the many interest groups associated with the health and well-being of U.S. cervids to commit to collective action and engagement, with a renewed sense of purpose and urgency.
Lonnie King, Chair
Committee on the Review of Transmission and Geographic Spread of Chronic Wasting Disease in U.S. Cervid Populations
Next-Generation Detection Assays
Postmortem Versus Antemortem Testing
Early Phase and Preclinical False Negatives
Biases in Sampling and Testing
Limitations and Promising Directions in Early CWD Prion Detection and Control
Early Warning Systems—New Horizons in Surveillance
5 EPIDEMIOLOGY AND ECOLOGY OF CHRONIC WASTING DISEASE
Patterns of Epidemic Growth and Apparent Geographic Spread
Drivers of Epidemic Growth and Geographic Spread
Impact of CWD on Cervid Population Dynamics
General Principles of Disease Management in Domestic and Wild Animals
Control of Other Transmissible Spongiform Encephalopathies
Gauging the Effectiveness of CWD Interventions
Approaches for Controlling CWD in Captive Cervids
Approaches for Controlling CWD in Free-Ranging Cervid Populations
Natural and Artificial Selection
Effectiveness of Public Messaging in CWD Management
Monitoring CWD Control Efforts
7 THE HUMAN AND SOCIOECONOMIC DIMENSIONS OF CWD
Cultural Dimensions: Impacts on Native Americans
Transmission Potential to Humans and Other Species
Social and Jurisdictional Factors
APPENDIX A: COMMITTEE BIOGRAPHICAL INFORMATION
APPENDIX B: PUBLIC MEETING AGENDAS
APPENDIX C: COMMONLY ASKED QUESTIONS
APPENDIX D: PUBLISHED DIAGNOSTIC TESTING PLATFORMS
APPENDIX E: SUPPLEMENTARY INFORMATION ON OTHER TSEs AND THEIR ECONOMIC IMPACTS
APPENDIX F: DATA ON CERVID FARMS AND CAPTIVE CERVIDS BY STATE AND COSTS
