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Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
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Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
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Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
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Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
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Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
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Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
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Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
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Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
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Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
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Summary BACKGROUND Brucellosis is a nationally and internationally regulated disease of livestock with significant conse- quences for animal health, public health, and international trade. In cattle, the primary cause of brucellosis is Brucella abortus, a zoonotic bacterial pathogen that also affects wildlife, including bison and elk. While B. abortus can cause both acute febrile and chronic relapsing brucellosis in humans, it is no longer a major human health concern in the United States due largely to public health interventions such as the pasteurization of milk and the successful efforts of the Brucellosis Eradication Program that began in 1934. As a result of the decades long eradication program, most of the country is now free of bovine bru- cellosis. The Greater Yellowstone Area (GYA), where brucellosis is endemic in bison and elk, is the last known B. abortus reservoir in the United States. The GYA is home to more than 5,500 bison that are the genetic descendants of the original free-ranging bison herds that survived in the early 1900s, and home to more than 125,000 elk whose habitats are managed through interagency efforts, including the National Elk Refuge and 22 supplemental winter feedgrounds maintained in Wyoming. Since the National Research Council (NRC) issued the 1998 report Brucellosis in the Greater Yel- lowstone Area, brucellosis has re-emerged in domestic cattle and bison herds in the GYA; from 1998- 2016, 22 cattle herds and 5 privately-owned bison herds were affected in Idaho, Montana, and Wyoming. During the same time period, all other states in the United States achieved and maintained brucellosis class-free status. A 2010 interim rule to regionalize brucellosis control enabled the three GYA states to create designated surveillance areas (DSAs) to monitor brucellosis in specific zones and to reduce the economic impact for producers in non-affected areas. However, brucellosis has expanded beyond the original DSAs, resulting in the outward adjustment of DSA boundaries. Although most cattle in the GYA are vaccinated with B. abortus strain RB51, it does not necessarily prevent infection while it does reduce abortions. The increase in cattle infections in the GYA, coupled with the spread in wildlife, has been alarming for producers in the area; moreover, the risk of additional spread from movement of GYA live- stock to other areas across the United States is increasing due to the lack of guidance and surveillance, with the potential for spread and significant economic impact outside the GYA. SCOPE AND APPROACH TO THE REVIEW The 1998 NRC report reviewed the scientific knowledge regarding B. abortus transmission among wildlife—particularly bison and elk—and cattle in the GYA. Given the scientific and technological ad- vances in two decades since that first report, the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (USDA-APHIS) requested that the National Academies of Sciences, Engineer- ing, and Medicine (the National Academies) revisit the issue of brucellosis in the GYA. The primary mo- tivation for USDA-APHIS in requesting the study was to understand the factors associated with the in- creased transmission of brucellosis from wildlife to livestock, the recent apparent expansion of brucellosis in non-feedground elk, and the desire to have science inform the course of any future actions in address- ing brucellosis in the GYA. Although USDA-APHIS commissioned the study to inform its brucellosis eradication strategy, there are additional federal and state agencies that each have authority across state, federal, private, and tribal lands that course through the GYA. Also, Yellowstone National Park (YNP) is Prepublication Copy—Subject to Further Editorial Revision 1

Revisiting Brucellosis in the Greater Yellowstone Area a national icon, American bison were recently designated as the national mammal, and the subject of bru- cellosis is of interest to many groups with economic interests in wildlife and livestock in the GYA. CONCLUSIONS AND RECOMMENDATIONS A New Focus on Elk In tracing the genetic lineage of Brucella across the ecosystem and among species, elk are now rec- ognized as a primary host for brucellosis and have been the major transmitter of B. abortus to cattle. All recent cases of brucellosis in GYA cattle are traceable genetically and epidemiologically to transmission from elk, not bison. The seroprevalence of brucellosis in elk in some regions has been increasing from what were historically low levels, and data strongly suggest that elk are able to maintain brucellosis infec- tion within their populations that have limited to no direct contact with the feedgrounds or with infected bison. Direct contact of elk with cattle is more prevalent than contact of cattle with bison. As a result, the risk of transmission from elk to cattle may be increasing. In contrast, there have been no cases of transmission from GYA bison to cattle in the 27 herds in- fected with brucellosis since 1998 despite no change in the seroprevalence of brucellosis in bison. This is likely a result of bison management practices outlined in the Interagency Bison Management Plan (IBMP) combined with fewer cattle operations in the GYA region where bison leave YNP. Ecological changes within the GYA since 1998 have shifted the dynamics of wildlife populations. The reintroduction of wolves and increases in grizzly bear numbers have impacted the density and distri- bution of elk. Elk populations have expanded on the periphery of the GYA but have decreased inside YNP. The rising number of private landowners has changed how land is used around national parks, with private lands increasingly serving as refugia for elk from hunting. With elk now viewed as the primary source for new cases of brucellosis in cattle and domestic bison, the committee concludes that brucellosis control efforts in the GYA will need to sharply fo- cus on approaches that reduce transmission from elk to cattle and domestic bison (Conclusion 1). Recommendation 1: To address brucellosis in the GYA, federal and state agencies should pri- oritize efforts on preventing B. abortus transmission by elk. Modeling should be used to character- ize and quantify the risk of disease transmission and spread from and among elk, which requires an understanding of the spatial and temporal processes involved in the epidemiology of the disease and economic impacts across the GYA. Models should include modern, statistically rigorous estimates of uncertainty. Adopting an Active Adaptive Management Approach Many brucellosis management efforts implemented since the 1998 report may appear to have taken an adaptive management approach; however, those efforts have not followed the basic tenet of employing an active approach. More specifically, individual management actions were not designed or established to allow for scientific assessment of effectiveness, which is a central tenet of active adaptive management. Management activities are typically conducted as hypothesis testing, the outcome of which directs subse- quent decisions and actions toward the ultimate goal. In the absence of carefully designed management actions that include experimental controls, it is difficult to determine the effectiveness of a particular prac- tice, leading to a slower learning process. Recommendation 2: In making timely and data-based decisions for reducing the risk of B. abortus transmission from elk, federal and state agencies should use an active adaptive management approach that would include iterative hypothesis testing and mandated periodic scientific assess- ments. Management actions should include multiple, complementary strategies over a long period 2 Prepublication Copy—Subject to Further Editorial Revision

Summary of time, and should set goals demonstrating incremental progress toward reducing the risk of transmission from and among elk. Adaptive Management Options to Reduce Risk No single management approach can independently result in reducing risk to a level that will prevent transmission of B. abortus among wildlife and domestic species (Conclusion 2). To consider any approach in isolation is to miss the bigger picture of a highly interconnected ecosystem and a broader understanding of various factors affecting risk that has evolved since 1998. While there are knowledge gaps that limit understanding of actual risk, the options below are possible adaptive management ap- proaches to reduce risk of B. abortus transmission and to inform future risk management plans. These approaches would need to be based on an integrated assessment of risk and costs, but do not necessarily need to be applied uniformly over space and time. Population Reduction Reducing the population size of cattle, bison, or elk are all likely to reduce the risk of brucellosis transmission to cattle by reducing the area of potential contact or the number of infected individuals in those areas, even if the disease prevalence in the wildlife hosts remains constant. However, each species has a constituency that would likely oppose any population reduction. Elk: Reducing the elk population is an option for reducing the risk of transmission among elk, cattle, and bison. Unlike bison, transmission among elk appears to be influenced by density. Thus, reducing elk group sizes and/or density may decrease elk seroprevalence over time, and potentially decrease the risk of elk transmission (Conclusion 3). Potential management approaches for elk population reduction include the following: • Hunting. Hunting is currently used to control elk populations, with management unit population targets set as a balance of public demand and population goals. Hunting could also be used as a means of incentivizing targeted population reductions based on brucellosis risk. Additional and ongoing assessments of the efficacy of these approaches would be needed as part of an active adaptive management approach. • Contraception. GonaCon™ is an immunocontraceptive that targets high-risk females; contra- ception would need to be viewed as experimental in elk but, as in bison, there is potential in sig- nificantly reducing the elk population and prevalence of brucellosis in elk. • Test and removal. Test and removal has been an invaluable part of the brucellosis eradication program for domestic species. As with domestic species, test and removal in elk would need to be part of an integrated program combined with other tools such as quarantine, herd manage- ment to reduce intra-herd transmission, and vaccination. Bison: While the primary focus would be on elk, bison remain an important reservoir for brucellosis. If further reducing the prevalence of brucellosis in bison is desirable, these bison population control measures could potentially be considered: • Removal of infected bison. Population reduction alone is not likely to reduce brucellosis preva- lence in bison since transmission is frequency dependent rather than density dependent. For this reason, if reduction of brucellosis prevalence is a goal, removal of bison for population management purposes will need to target brucellosis infected individuals, whenever possi- ble (Conclusion 4). Prepublication Copy—Subject to Further Editorial Revision 3

Revisiting Brucellosis in the Greater Yellowstone Area • Quarantine and relocation. Sufficient evidence is now available to also include separation and quarantine of test negative bison as a management action, allowing for the eventual relocation of GYA bison to other bison herds (including onto tribal lands). • Targeted removal within YNP. While this option may not be politically, logistically, socially, or economically feasible, targeted removal of seropositive bison (which would be facilitated by the use of a pen-side assay) or high-risk bison (such as young, pregnant females) within YNP in the winter could reduce the need for large culls of bison populations that move outside YNP. This could also reduce the episodic swings in the bison population and winter emigrations from YNP that lead to large culls in some years. • Bison genetics. Test and removal of bison provides a valuable opportunity to preserve genetic material and live cells for future use in establishing brucellosis negative and potentially disease resistant bison through cloning techniques. • Contraception. Experimental and modeling results in bison suggest that contraception using a gonadotropin releasing hormone immunocontraceptive (i.e., GonaCon™) may help in reducing the prevalence of brucellosis. This approach targets high-risk females, preventing pregnancy and thus abortion and birthing events that increase risk of transmission through shedding of high numbers of bacteria. Intervention Options Within Feedgrounds The role of the National Elk Refuge and Wyoming elk supplemental winter feedgrounds in main- taining and propagating brucellosis in the GYA is a controversial topic. Feedgrounds have been useful for conservation and hunting purposes, and for separating elk from cattle. However, it is widely accepted that feedgrounds promote transmission of B. abortus among elk and are likely responsible for causing and maintaining elevated seroprevalence in those areas. The potential options below for management interventions in feedgrounds could be further evaluat- ed using an active adaptive management approach, with the interventions applied singularly or in combi- nation. • Balance the timing and use of feedgrounds. Data suggest that ceasing feeding earlier in the sea- son on feedgrounds to encourage dispersal would result in less risk of infection among elk (and bison where intermixing occurs), because calving of elk would occur in a more natural envi- ronment away from the dense population present in feedgrounds. • Feeding patterns on feedgrounds. Data suggest that feeding in checkerboard patterns and spreading feed more broadly appear to reduce elk to elk contact, and therefore potentially reduce transmission risk. • Test and removal on feedgrounds. The Muddy Creek feedground pilot project provided an ex- ample of temporarily reducing seroprevalence of brucellosis through test and removal of infect- ed female elk. Its use would be limited to very specialized conditions (e.g., in reducing feed- ground density) as large populations appear to be able to maintain a brucellosis reservoir outside the feedgrounds. • Contraception in elk. The feedgrounds provide an opportunity to more easily access female elk for contraceptive application. • Removal of aborted fetuses. Abortion on feedgrounds offers an opportunity to remove aborted fetuses on a daily basis and to disinfect the abortion site using an appropriate disinfectant, thus reducing the likelihood of transmission to other elk. • Other future interventions. Given the enormity of the challenge in accessing elk in the vastness of the open West, feedgrounds offer a unique opportunity to intervene in a relatively smaller land area where elk are concentrated and capture is easier, less dangerous for personnel, and less costly. 4 Prepublication Copy—Subject to Further Editorial Revision

Summary Incremental Closure of Feedgrounds Closure of feedgrounds appears to be an obvious approach to control brucellosis in the GYA, but there are impacts of feedground closure that will need to be considered and assessed. First, while there is still some uncertainty, scientific evidence suggests that brucellosis in elk is self-sustaining in some areas without continuous reintroduction of infected feedground elk. If future work continues to support this conclusion, it is possible that closure of feedgrounds would not have any impact on brucellosis prevalence in more remote elk populations away from the feedgrounds. Closure of feedgrounds would, however, po- tentially reduce the “seeding” of new areas with infected elk where a reservoir does not currently exist. Second, anecdotal evidence suggests that feedgrounds reduce exposure of cattle to infected elk during the high-risk period of abortion or calving. Observational data to support this notion are weak at present. Thus, an unintended outcome of closing feedgrounds could be increased exposure of cattle to infected elk if cattle are turned onto grazing areas at the time that elk are calving. The weight of evidence nonethe- less suggests that reduced use or incremental closure of feedgrounds could benefit elk health in the long-term, and could reduce the overall prevalence of brucellosis in elk on a broad population basis (Conclusion 5). The closure of feedgrounds is likely to bring increased short-term risk due to the potential for in- creased elk-cattle contact while the seroprevalence in elk remains high. In the longer term, closing feed- grounds may result in reduced elk seroprevalence. Reduced use or incremental closure of feedgrounds is not a stand-alone solution to control of brucellosis in the GYA, and will need to be coupled with other management actions to address the problem at a systems level (Conclusion 6). Recommendation 3: Use of supplemental feedgrounds should be gradually reduced. A strate- gic, stepwise, and science-based approach should be undertaken by state and federal land managers to ensure that robust experimental and control data are generated to analyze and evaluate the im- pacts of feedground reductions and incremental closure on elk health and populations, risk of transmission to cattle, and brucellosis prevalence. Spatial and Temporal Separation One of the fundamental principles of infectious disease control is spatial and temporal separation of individuals and groups to reduce the risk of transmission. Bison management to prevent brucellosis transmission has been successful in part due to spatial and temporal separation from cattle, both because bison are largely contained within YNP and Grand Teton National Park, and when outside the parks they are managed to reduce cattle contact. Recommendation 4: Agencies involved in implementing the IBMP should continue to maintain a separation of bison from cattle when bison are outside YNP boundaries. Spatial and temporal separation also plays an important role in reducing transmission risk from elk. Separation of susceptible and infected animals during high-risk periods has been and should continue to be utilized as a risk reduction tool, and is further discussed in the report in the context of specific man- agement approaches. National policy for responding to the identification of infected cattle and domestic bison herds includes time-tested approaches toward maintaining separation of infected and susceptible animals, including hold orders and quarantine during follow-up testing. These actions are valuable tools for reducing risk. Other options include the timing and use of grazing allotments, biosecurity measures, and hazing of elk. Removal of bison for population management purposes could target B. abortus infected individuals if further reducing the prevalence of brucellosis is a goal; however, until tools become availa- ble that would simultaneously allow for an eradication program in elk, additional aggressive control measures in bison seem unwarranted. Prepublication Copy—Subject to Further Editorial Revision 5

Revisiting Brucellosis in the Greater Yellowstone Area Testing, Surveillance, and Designated Surveillance Areas Regionalization is now a well-accepted approach to allow subnational disease containment without jeopardizing the disease status of an entire nation. The success of regionalization relies on robust risk as- sessment, knowledge of the location and extent of infected animals within and immediately outside the boundary of a control zone, and effective boundary management and enforcement. The designated surveillance area (DSA) zoning concept is a valuable approach toward brucellosis control in the GYA. The successful use of DSAs is dependent on responsible and timely adjustments of DSA boundaries based on adequate surveillance, particularly of elk. There is no federal guidance for con- ducting wildlife surveillance outside of the DSA at a level required to monitor the geographic expansion of brucellosis in elk. Each state independently conducts wildlife surveillance outside of the DSA, with no uniform data-based guidelines or requirements for states to reference in determining when to expand their DSA as a result of finding infected or exposed wildlife outside of established DSA boundaries. This lack of uniformity in rules and standards has resulted in an uneven approach to surveillance and to establishing boundaries that accurately reflect risk. If DSA boundaries are not expanded in a timely manner in re- sponse to finding seropositive wildlife, there is an increased probability that exposed or infected cattle and domestic bison herds in that area may not be detected in time to prevent further spread of infection as cat- tle and domestic bison are marketed and moved. There is no major slaughter capacity in Montana or Wy- oming where surveillance samples can be collected to detect whether brucellosis has expanded in cattle beyond the DSA boundaries. This gap in slaughter surveillance for non-DSA cattle in the GYA states fur- ther raises the risk of brucellosis spreading beyond the DSAs. The lack of data-based guidance and uniformity in conducting wildlife surveillance outside the DSA, the absence of a GYA focused approach for national surveillance, and the infrequent over- sight of state brucellosis management plans in the midst of expanding seroprevalence of elk has in- creased the risk for spread of brucellosis in cattle and domestic bison outside the DSA boundaries and beyond the GYA (Conclusion 7). Recommendation 5: In response to an increased risk of brucellosis transmission and spread beyond the GYA, USDA-APHIS should take the following measures: 5A: Work with appropriate wildlife agencies to establish an elk wildlife surveillance program that uses a modeling framework to optimize sampling effort and incorporates multiple sources of uncertainty in observation and biological processes. 5B: Establish uniform, risk-based standards for expanding the DSA boundaries in response to finding seropositive wildlife. The use of multiple concentric DSA zones with, for example, different surveillance, herd management, biosecurity, testing, and/or movement requirements should be con- sidered based on differing levels of risk, similar to current disease outbreak response approaches. 5C: Revise the national brucellosis surveillance plan to include and focus on slaughter and market surveillance streams for cattle in and around the GYA. Vaccination Vaccination is a time-tested, proven method of infectious disease control. Brucellosis vaccination has been an important part of the program to eradicate brucellosis from domestic cattle, and is effective when used in conjunction with other disease management approaches such as quarantine, herd manage- ment to reduce intra-herd transmission, and test and removal. The significant reduction in risk of transmission among vaccinated cattle provides sufficient reason to continue calfhood and adult vaccination of high-risk cattle when coupled with other risk reduction approaches (Conclusion 8). An improved vaccine for each of the three species (elk, bison, and cattle) would help suppress and eventually eliminate brucellosis in the GYA. For free-ranging bison and elk, appropriate and cost- effective vaccine delivery systems would be critical. However, until the issue of infected elk transmitting B. abortus to cattle is fully addressed, there will still be a perception of risk by other states that would 6 Prepublication Copy—Subject to Further Editorial Revision

Summary likely drive continued testing of cattle leaving the DSAs even if cattle are vaccinated with a highly effec- tive vaccine. Bioeconomics: A Framework for Making Decisions Economic resources for managing disease risks in the GYA are scarce. Any management strategies that impose costs on agencies and other stakeholders while producing few benefits will not be adopted. Costs are not limited to direct monetary costs of undertaking management actions, and benefits are not limited to reduced economic risks to cattle producers; the costs and benefits also include the positive and negative impacts to the ecological processes of the region that are directly or indirectly valued by stake- holder groups. Moreover, many costs and benefits ultimately depend on how individual ranchers, land- owners, and resource users respond to changes in risk. Many of these costs and benefits will not be real- ized in the short term, and thus a long-term perspective is needed in managing the entire system. Bioeconomic modeling provides a valuable framework for systems-level decision making that is able to take into account the socioeconomic costs and benefits of reducing transmission from wildlife to domestic cattle and bison, and is able to promote coordination and targeting of actions spatially and temporally based on expected costs and benefits, including potential impacts beyond the GYA. While the Statement of Task requests a cost-benefit analysis for various management options, a lack of critical information severely limits the committee’s ability to develop a comprehensive empirical assessment at this time. There are significant knowledge gaps for key economic and disease ecology relations, including the effec- tiveness, cost, and unanticipated impacts of various candidate management options to control brucellosis in the broader GYA system. A coupled systems/bioeconomic framework is vital for evaluating the socioeconomic costs and benefits of reducing brucellosis in the GYA, and would be needed to weigh the potential costs and benefits of particular management actions within an adaptive management setting. A bioeconomic framework is also needed to identify appropriate management actions to target spatial-temporal risks, including risks beyond the GYA (Conclusion 9). A Call to Strategic Action The current committee echoes the sentiments from the 1998 NRC report and concurs that eradica- tion of brucellosis from the GYA remains idealistic, but is still not currently feasible for scientific, social, political, and economic reasons. However, while eradication of brucellosis in the GYA remains a distant goal, significant progress toward reducing or eliminating brucellosis transmission from wildlife to domes- tic species is possible. Undoubtedly, sufficient societal and political will along with sufficient financial resources will be required for success. Managing an ecosystem as complex as the Greater Yellowstone Ecosystem will require coordination and cooperation from multiple stakeholders, and will require expertise across many disciplines to understand the intended and unintended costs and benefits of actions (Conclusion 10). Addressing brucellosis under the new and changing conditions in the region necessitates a more systematic, rigorous, and coordinated approach at several levels—from priority set- ting to information gathering, data sharing, and wildlife and disease management—than has occurred thus far. A strategic plan is needed to coordinate future efforts, fill in critical knowledge and information gaps, and determine the most appropriate management actions under a decision-making frame- work that is flexible and accounts for risks and costs (Conclusion 11). Recommendation 6: All federal, state, and tribal agencies with jurisdiction in wildlife man- agement and in cattle and domestic bison disease control should work in a coordinated, transparent manner to address brucellosis in multiple areas and across multiple jurisdictions. Effectiveness is dependent on political will, a respected leader who can guide the process with goals, timelines, measured outcomes, and a sufficient budget for quantifiable success. Therefore, participation of Prepublication Copy—Subject to Further Editorial Revision 7

Revisiting Brucellosis in the Greater Yellowstone Area leadership at the highest federal (Secretary) and state (Governor) levels for initiating and coordi- nating agency and stakeholder discussions and actions, and in sharing information is critical. Coordinating a Complex System Management of brucellosis in the GYA is under the jurisdiction of various state, federal, private, and tribal authorities. Each entity has its own mission and goals, and at times these goals may conflict with one another. In addition, there are private landowners, hunters, and ranchers whose actions can im- pact and are impacted by the decisions of others. To date, the efforts undertaken by various state and fed- eral entities have been conducted in a piecemeal fashion, resulting in a disjointed and uneven approach. Moreover, actions taken have not been effective in addressing the problem, because they have not ad- dressed the issues on a systems level. While each state has the right to establish independent management approaches, management actions within each state can have external impacts for the other two states in the GYA and beyond; similarly, each federal agency has the right to establish independent management approaches for their area of jurisdiction, yet there may be unintended consequences that impact the mis- sion and goals of other agencies. Thus, coordinated efforts across federal, state, and tribal jurisdic- tions are needed, recognizing firstly that B. abortus in wildlife spreads without regard to political boundaries, and secondly that the current spread of brucellosis will have serious future implica- tions if it moves outside of the GYA (Conclusion 12). Future progress will depend on actions of private and public stakeholders, and will require integrating multiple scientific approaches. Integration of Management Approaches Historically, there was great interest in brucellosis at the highest levels of government through the Greater Yellowstone Interagency Brucellosis Committee. While the threat has expanded since 1998, the participation of essential stakeholders has diminished due to loss of interest caused by lack of a positive outcome or productive movement in the disease progression within the wildlife populations. There is a need to reinvigorate this interest with buy-in and participation of leadership and development of a mecha- nism for coordinating policy and management actions. Integration of Scientific Approaches Lack of openly accessible data has limited the amount of scientific progress on controlling brucello- sis, slowed the learning process, and limited critical information necessary for making decisions. A forum to coordinate scientific approaches toward brucellosis control among all states and agencies with jurisdic- tion in the GYA would be a valuable mechanism to ensure that science informs policy. Such a body would share information, prioritize research projects, limit duplication of efforts, advise on management actions, and serve as a potential venue for communicating scientifically sound and agreed-upon messages and policies to the public. Addressing Knowledge Gaps Through Research Eliminating B. abortus transmission within wildlife populations (elk and bison) and from wildlife to cattle and domestic bison in the GYA—and by extension, eliminating it from the United States—is not fea- sible unless critical knowledge gaps are addressed. An integrated, multi-disciplinary approach is necessary for addressing multiple aspects of the problem, thus research teams will need to include members from vari- ous disciplines who provide relevant expertise and understanding. This will also require collaboration and coordinated communications among the university, agency, and nonprofit research communities. 8 Prepublication Copy—Subject to Further Editorial Revision

Summary Recommendation 7: The research community should address the knowledge and data gaps that impede progress in managing or reducing risk of B. abortus transmission to cattle and domes- tic bison from wildlife. 7A: Top priority should be placed on research to better understand brucellosis disease ecology and epidemiology in elk and bison, as such information would be vital in informing management decisions. 7B: To inform elk management decisions, high priority should be given to studies that would provide a better understanding of economic risks and benefits. 7C: Studies and assessments should be conducted to better understand the drivers of land use change and their effects on B. abortus transmission risk. 7D: Priority should be given to developing assays for more accurate detection of B. abortus in- fected elk, optimally in a format capable of being performed “pen-side” to provide reliable rapid results in the field. 7E: Research should be conducted to better understand the infection biology of B. abortus. 7F: To aid in the development of an efficacious vaccine for elk, studies should be conducted to understand elk functional genomics regulating immunity to B. abortus. 7G: The research community should (1) develop an improved brucellosis vaccine for cattle and bison to protect against infection as well as abortion, and (2) develop a vaccine and vaccine de- livery system for elk. CONCLUDING REMARKS Even over the course of the committee’s 16-month review, there were rapid changes in management practices and new cases of brucellosis in cattle and domestic bison, which reemphasizes the difficulty in handling this complex and expanding problem. Brucellosis was eliminated from cattle in the United States after nearly a century of dedicated funding and resources from USDA, states, and livestock pro- ducers. With increasing incidence of brucellosis in cattle and domestic bison herds in the GYA in the past few decades due to transmission from elk, significant resources are needed to address a problem that is expanding in scale and scope; without the changes and investments necessary to aggressively address this problem in a coordinated and cost-effective manner, brucellosis may spread beyond the GYA into other parts of the United States resulting in serious economic and potential public health consequences. Efforts to reduce brucellosis in the GYA will depend on significant cooperation among federal, state, and tribal entities and private stakeholders as they determine priorities and next steps in moving forward. The re- port’s intent is to be useful for decision makers and stakeholders as they address the challenging matter of brucellosis in the GYA. Prepublication Copy—Subject to Further Editorial Revision 9

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Brucellosis is a nationally and internationally regulated disease of livestock with significant consequences for animal health, public health, and international trade. In cattle, the primary cause of brucellosis is Brucella abortus, a zoonotic bacterial pathogen that also affects wildlife, including bison and elk. As a result of the Brucellosis Eradication Program that began in 1934, most of the country is now free of bovine brucellosis. The Greater Yellowstone Area (GYA), where brucellosis is endemic in bison and elk, is the last known B. abortus reservoir in the United States. The GYA is home to more than 5,500 bison that are the genetic descendants of the original free-ranging bison herds that survived in the early 1900s, and home to more than 125,000 elk whose habitats are managed through interagency efforts, including the National Elk Refuge and 22 supplemental winter feedgrounds maintained in Wyoming.

In 1998 the National Research Council (NRC) issued a report, Brucellosis in the Greater Yellowstone Area, that reviewed the scientific knowledge regarding B. abortus transmission among wildlife—particularly bison and elk—and cattle in the GYA. Since the release of the 1998 report, brucellosis has re-emerged in domestic cattle and bison herds in that area. Given the scientific and technological advances in two decades since that first report, Revisiting Brucellosis in the Greater Yellowstone Area explores the factors associated with the increased transmission of brucellosis from wildlife to livestock, the recent apparent expansion of brucellosis in non-feedground elk, and the desire to have science inform the course of any future actions in addressing brucellosis in the GYA.

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