Conservation Medicine : Ecological Health in Practice

CONSERVATION MEDICINE ECOLOGICAL HEALTH IN PRACTICE

Edited by

A. Alonso Aguirre Richard S. Ostfeld Gary M. Tabor Carol House Mary C. Pearl

OXPORD UNIVERSITY PRESS

2002

19 Ecological Health and Wildlife Disease Management in National Parks Colin M. Gillin Gary M. Tabor A. Alonso Aguirre

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nce considered to be shining examples of pristine nature, national parks and other conservation protected areas are facing increasing threats to their ecological integrity. Habitat fragmentation and degradation, habitat loss, species extinctions, alien species introductions, pollution, and recreational overusage represent some of the cumulative effects that are putting these areas of natural heritage under increasing stress. Long considered a footnote to protected area management, health concerns are gaining greater attention in protected areas as cumulative stresses are enhancing, and sometimes amplifying, conditions for disease and other health effects. In this chapter we discuss the influence of pollution and disease and other health effects on the integrity of parks and protected areas. Protected areas are relatively undisturbed natural ecosystems set aside from human development and provided of legislative protection with the National Park Service Organic Act of 1916 (MacKintosh 1991). Despite protection from human influence to habitat and animal population numbers, the health of wildlife is intertwined with the influences of the encompassing ecosystem, both inside and outside park boundaries. Those influences will continue to increase as park visitor numbers increase, leading to behavioral stress on wildlife. Other environmental stressors including pollution from automobiles, snowmobiles, and upwind airborne contaminants lead to changes in the environment and degradation of the stability of these ecosystems. The health and environmental stability of areas protected and conserved for natural resources can be measured by evaluating the pathologic changes threatening wildlife, humans, and plants within an ecosystem. In 1941, Aldo Leopold wrote, "A science of land health needs, first of all, a base-datum of normality, a 253

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picture of how healthy land maintains itself as an organism." Wagner and Colleagues (1995) and Krausman (1998) suggested that national parks could serve as a model to determine healthy, relatively pristine areas. Historical records may also provide the foundation to begin a database to determine the health of a protected ecosystem from which we can build upon through time and space. Collectively, a series of "snapshots" can provide a picture to document health issues throughout selected national parks in North America. In addition, longterm monitoring may be indicated in these protected areas to assess the effects of anthropogenic impact.

19.1 Historical Perspective The National Park service administers approximately 80.7 million acres (32.6 million hectares) in the United States, of which more than 2.8 million acres remain in private ownership. The largest area is Wrangell-St. Elias National Park and Preserve, Alaska, at 13.2 million acres, 16.3% of the entire system. The smallest unit in the system is Thaddeus Kosciuszko National Memorial, Pennsylvania, at 0.02 of an acre. In protecting and governing these federal lands, the Yellowstone National Park Act of 1872 was established and then strengthened with the National Park Service Organic Act of 1916. The National Park Act designated land set aside for the preservation of natural resources at the exclusion of human development and resource exploitation such as hunting, mining, and consumptive activities. In effect, these lands were set aside and protected from the influences of human development and change. Some influences and changes, however, do not fall within the scope of these acts.

19.2 National Parks and Conservation Medicine A recent U.S. Environmental Protection Agency and National Park Service study found that snowmobile use in Yellowstone National Park produced unacceptable and damaging levels of air pollutants (U.S. Environmental Protection Agency 1999a,b,c; U.S. Department of the Interior 2000). This study led to a ban on snowmobile use as a means of winter travel in the parks. An increasing number of diseases and their vectors in wildlife of national parks have most likely originated from contact with humans, domestic pets, and livestock within parks and in surrounding gateway communities (Aguirre et al. 1995a). Diseases, whether endemic or exotic, are capable of migrating with wildlife, particularly those that migrate long distances as with arboviruses in birds and bats (McLean 1991; Ubico and McLean 1995). The threats and issues that affect protected areas within and beyond park boundaries are prime examples of bringing together the essence of defining the field of conservation medicine. The health of Yellowstone National Park, the first national park in North America, is the subject of a current issue that has caught

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the attention of local and national environmental activists, gateway communities, and government officials (Broscious 1998; Janofsky 1999). In 1995, the U.S. Department of Energy contracted with a nuclear waste company to build a radioactive and hazardous waste facility 90 miles northwest of the park. One of the primary issues was that prevailing winds could carry accidental or intentional emissions of radioactive particles into not only Yellowstone National Park but also Grand Teton National Park. The primary public concern was fear of radioactive exposure, threats to public health from increased cancer rates, and environmental contamination in one of the most unspoiled areas of North America. Pollution effects can ultimately cause pathologic changes that are detrimental to the individual animal, the population, and eventually the ecosystem. A decrease in animal health and human health, a loss of the "unspoiled" nature of national parks through environmental degradation, and negative economic effects on the gateway communities all pose the potential to decrease ecological health. Although the project has been derailed, the health of people and park resources were sufficiently important to evaluate the interrelationships between ecological and environmental health. The issues evaluated in this scenario demonstrated that parks are not isolated ecologically and as such they experience effects in all the interconnected areas, perceived as natural or disturbed. Conservation medicine refers to the practice of ecological health and its connections with animals, humans, and the environment. It requires integrating health parameters across species, across landscapes, and across disciplines.

19.3 Health Issues in National Parks National parks do not encapsulate pristine environs despite their legal protection. The health of wildlife communities in a national park is not guaranteed. Habitat fragmentation, changes in vegetative composition due to the consequences of "natural regulation" and behavior, and the increasing human pressures in and around parks have created a barrage of ecological health effects. This can manifest through the introduction of alien species, the presence of wildlife diseases, and the threat of waterborne and airborne pollutants. These effects are not new and have taken a toll on park resources and management since their inception (Clark 2000). There is evidence that most diseases diagnosed in wildlife, except for some native parasitic infections, first originated in human or domestic animal populations. Following eradication or control in domestic animals, many of those diseases have found a wildlife host or a sylvatic cycle (Aguirre et al. 1994). Diseases transmitted from wildlife to humans or to domestic animals may create crises in public health or animal welfare. For example, brucellosis, a bacterial zoonosis caused by Brucella abortus, is characterized by abortions, arthritis, and reproductive failure in domestic livestock. The actual source of the disease in the Greater Yellowstone Area (GYA) is unknown; however, B. abortus was introduced in North America with cattle imported from Europe. Brucella may have been introduced in Yellowstone National Park as early as 1902 with bison (Bison bison) from Montana and Texas during


efforts to improve the population numbers of an almost extinct park bison herd. The disease was first identified serologically in bison in the park in 1917 (Mohler 1917; Rush 1932). Meagher and Meyer (1994) concluded that Brucella was likely introduced to wildlife in Yellowstone National Park through cattle maintained for park employees. Both wapiti (Cervus elaphus) and bison are infected in the GYA (Nettles 1992). Wapiti on state-run winter feeding grounds maintain a seroprevalence rate of approximately 24%, and 50% of the bison herd are infected in the GYA (Thorne et al. 1978, 1991a,b; Williams et al. 1993). Approximately 46% of these bison will yield pure culture for Brucella (Roffe et al. 1999). Since 1925, bison at Wood Buffalo National Park, Northwest Territories, Canada, have been infected not only with Brucella but also with bacteria causing bovine tuberculosis, complicating the scenario (Joly et al. 1998; Tessaro et al. 1990). These diseases were transported from an introduced subspecies of bison relocated from Alberta, Canada. Johne's disease (Mycobacterium paratuberculosis), another chronic disease principally seen in livestock, was also diagnosed in this population (B. Elkin, Government of the Northwest Territories, personal commun. 2000). There are several diseases of zoonotic importance that have been identified in North American national parks, including tick-borne relapsing fever in Grand Canyon National Park (Boyer et al. 1977), Colorado tick fever in Rocky Mountain National Park (McLean et al. 1989), and sylvatic plague (Yersinia pestis) in rodents in Lava Beds National Monument (Stark and Kinney 1969; Nelson and Smith 1976). Diseases affecting ungulates have been recorded in other national parks, including leptospirosis (Leptospira spp.) in white-tailed deer (Odocoileus virginianus) in Great Smokey Mountain National Park, Tennessee (New et al. 1993), and hemorrhagic septicemia in bighorn sheep (Ovis canadensis) in Rocky Mountain National Park, Colorado (Potts 1937). Parasitic nematode eye worms have been recorded in mule deer in Sequoia National Park, California, and studies of the intestinal parasites of small mammals were conducted in Grand Teton National Park (Oberhansley 1940; Pinter et al. 1988). In a study conducted by Aguirre et al. (1993, 1995b), the most common wildlife diseases found in national parks were those affecting ungulates. These included lungworm-pneumonia complex in bighorn sheep and epizootic hemorrhagic dieases in white-tailed deer. Other ungulate diseases reported were meningeal worm (Parelaphostrongylus) infections in wapiti and deer, psoroptic scabies (Psoroptes ovis) in bighorn sheep, leptospirosis in deer, and pseudorabies in feral pigs (Sus scrofd). Carnivores in national parks were reported with rabies, sylvatic plague, canine distemper, borreliosis (Borrelia burgdorferi), and filarial (Dirofilaria spp.) infections. Other diseases have been documented as to be increasing in zoonotic importance in national parks, including tularemia (Fransicella tularensis) in rabbits (Sylvilagus spp.) and American beavers (Castor canadensis), and leptospirosis, giardiasis (Giardia spp.), and Rocky Mountain spotted fever in rodents (Aguirre et al. 1993, Aguirre and Starkey 1994). Domestic livestock pathogens are commonly transmitted from cattle to wild cervids. In a survey of several western U.S. national parks, populations of mule deer (Odocoileus hemionus) and wapiti presented high liters to parainfluenza-3 virus, bovine herpes virus-1, bovine viral diarrhea virus, bovine respiratory syn-


cytial virus, blue tongue virus, and epizootic hemorrhagic disease virus (Aguirre et al. 1995b). During a similar study in Banff National Park, Canada, wapiti and moose (Alces alces} tested positive for antibodies to bovine viral diarrhea virus, bovine herpesvirus-1, and Leptospira icterohemorrhagiae (T. Shury, Parks Canada, personal commun. 1999). In national parks of the western United States, gray wolves (Canis lupus} have been shown to carry antibodies to canine distemper, canine parvovirus, and infectious canine hepatitis (Johnson et al. 1994). Other canid species, including coyotes (C. latrans} and red fox (Vulpes fulva), occupying the same range are most likely exposed to similar diseases. Hantavirus and sylvatic plague have been documented in deer mouse (Peromyscus maniculatus} and vole (Microtus spp.) populations within Grand Teton and Yellowstone National Parks (Jannett 1996; M. Johnson, unpublished data 2000). Diseases in national parks are not limited to terrestrial ecosystems. Whirling disease (Myxobolus cerebralis}, a parasitic disease that kills salmonid fish species, including rainbow (Oncorhynchus mykiss} and cutthrout trout (O. clarki}, was discovered in the Madison River of Yellowstone National Park in 1994 (Baldwin et al. 1997; Egan 1999). The disease is spread through introduction of fish reared in hatcheries. Biologists have witnessed increased stress on wildlife populations due to lice infestations in Denali National Park, Alaska (P. Owens, Denali National Park Research and Resources Division, personal commun. 2000). Due to the large domestic dog population (including sled dogs) in the state and outside the park, canine parvovirus, canine distemper, and infectious canine hepatitis may be transmitted to wild carnivore populations (Elton 1931; Stephenson et al. 1982). Canine parvovirus was suspected to reduce gray wolf (Canis lupus} pup survival from 80% to 60% in the reintroduced populations of Central Idaho and the Yellowstone National Park during 1999 (E. Bangs, Wolf Recovery Coordinator, personal commun. 2000). Wolves of Glacier National Park, Montana, have also been affected by canine parvovirus and canine distemper (Johnson et al. 1994). In many national parks of the Eastern Seaboard, tick-borne diseases such as Lyme disease (Borrelia burgdorferi) continue to present challenges to park management as human exposure increases with increased numbers of visitors (K. Anderson, Acadia National Park, personal commun. 2000). There is also an increased threat of rabies from infected raccoon populations as the disease epidemic has continued to spread northward from the southeastern United States since the 1970s (Rupprecht and Smith 1994). Hantavirus infection and sylvatic plague are at the forefront of zoonotic disease concerns in parks where the diseases likely exist and human contact with small mammals is evidently high (S. Cain, Grand Teton National Park, personal commun. 2000).

19.4 Management Implications As a consequence to the presence of pathogens, park managers attempt to institute procedures to reduce risk of exposure to disease and zoonotic potential. For ex-


ample, when researchers enter caves to study colonies of bats in Carlsbad Caverns National Park, New Mexico, they are required to wear respirators to reduce inhalation exposure from airborne pathogens. They also must have been previously immunized with a rabies vaccine (D. Pate, Carlsbad Caverns National Park, personal commun. 2000). The National Park Service uses veterinary epidemiologists from the National Wildlife Health Center, the Biological Resources Division of the U.S. Department of Interior, and the Animal Plant Health Inspection Service of the U.S. Department of Agriculture (USDA) with diseases of economic and national importance such as brucellosis. Park managers surveyed in several national parks across the country, however, were not aware of contingency plans in the event of a major disease outbreak. In general, these managers plan to work in coordination with state and federal wildlife agencies, but only if they believe intervention is warranted (Aguirre et al. 1993; Aguirre and Starkey 1994). The current park policy on disease has evolved since the adoption of the National Park Service Management Policy (U.S. National Park Service 1988). In this policy, "intervention on the part of the Centers for Disease Control (CDC) will be used in cases of exotic species management when threatening situations pose a public health hazard as determined or a hazard to public safety." Now, however, disease intervention may also be used in pest management, including "many fungi, insects, rodents, diseases, and other species that may be perceived as pests and are native plants and animals existing under natural conditions as natural elements of the ecosystem." Management strategies may be implemented to control disease if a human health hazard as defined by the CDC exists or to protect against a significant threat to public safety. Diseases in native animals may also be controlled if the disease is an exotic organism; likely to be transmitted to livestock; a threat to human health; a natural disease, but conditions which would contribute to natural limitation of the spread of the disease are no longer present; if the disease threatens to extirpate a relict population from the park or threatens a threatened or endangered species; or upon completion of a plan approved by the Regional Director" (U.S. National Park Service 1994)

Natural regulation is the principal National Park Service policy concerning animal handling and disease issues. Handling of animals for disease treatment or specimen collection is generally not permitted (Zaugg et al. 1993). As part of the hands-off natural regulation policy, parks will not control diseases when they are endemic, are part of natural regulation of wildlife populations, and are not a threat to humans, livestock, or agriculture operations adjacent to parks (D. Barna, Chief of Public Affairs, National Park Service, Washington, D.C., personal commun. 2000). Under the NPS-77 guidelines (U.S. Park Service 1994), disease will not be controlled when the effort would prove impractical or would threaten other wildlife populations in the process. But if treatment is indicated, parks are required to institute a monitoring program to evaluate the effects of the treatment. There is no documentation of eradication of any major disease in North American national parks. This is most likely due to a low emphasis on health and disease issues, a lack of personnel assigned or trained to the task, and inadequate


record keeping/documentation. Historically, researchers have demonstrated diseases present in national parks that cause economic and human health risks. Many diseases are studied because they occur in epidemic proportions or a disease is identified incidentally. When mapped on a continental scale, disease distribution correlates to animal distributions, which are often fragmented in islands of habitat. Monitoring yields useful data whether positive or negative. For example, in 1999, veterinary researchers in Banff National Park tested sera from over 100 elk and approximately 40 other individual moose, bear (Vrsus americanus), cougar (Felis concolor), coyote (Canis latrans), and lynx (Lynx canadensis). They found no animals seropositive for Brucella abortus, indicating that none of the animals were previously exposed (T. Shury, Parks Canada, personal commun. 1999). The uniformly negative results of this survey are valuable in defining the geographical extent of B. abortus infection. In the Rocky Mountain region of the United States and Canada, wildlife veterinarians are mapping important wildlife diseases using geographical information systems (GIS) technology to identify known distribution of diseases, including brucellosis, chronic wasting disease, anthrax, bovine tuberculosis, sylvatic plague, and hantavirus (C. Gillin et al., unpublished data, 2000). This information will also identify information gaps in national parks throughout the Rockies and provide agency managers with a common database that spans jurisdictional boundaries. More important, this technology provides health professionals a means of evaluating ecological health involving human and animal well-being, the biotic environment (habitat quality and food supply), and physical environment (weather, climate, and edaphic conditions) and other data including socioeconomic or cultural information. Health researchers and agency personnel in Canada recently participated in a workshop in Pacific Rim National Park on Vancouver Island, where the goal was to develop a set of measures to track the ecological integrity of the park (C. Stephen, Center for Coastal Health, personal commun. 2000). This workshop was established because Canada's national parks now have the mandate to protect and promote ecological integrity rather than tourism and recreation. During the proceedings participants identified the need for surveillance and monitoring systems to track disease and mortality as important indicators of ecological integrity. Other "indicators" included surveys of keystone or significant species, habitat mapping, and monitoring human impacts. Marine protected areas of Canada are also being looked at as important areas in ecological health. Socioeconomic and other values have been provided to create tools for the establishment of marine parks, including a proposed park in the southern Georgia Strait in British Columbia. Other provincial parks have elicited outside veterinary expertise in the evaluation of mass mortalities of wildlife. These included a large die-off at a gull colony and evidence of mass mortality of northern fulmars (Fulmaris glacialis) occurring along the Pacific coast and potentially affecting Pacific Rim National Park (C. Stephen, Center for Coastal Health, personal commun. 2000). Initial concerns involving these die-offs were related to toxin exposure with implications to animal and human risks.


19.5 Achieving Ecological Health in National Parks In 1995, Aguirre et al. (1995a) argued for a national surveillance program for wildlife diseases in national parks. Due to dramatic increases in ungulate and other wildlife populations in many national parks, a disease surveillance program could help park managers approach decisions prior to a population crisis or epidemic (Porter et al. 1994). Wildlife populations serve as sentinels of the health and quality of the environment and are capable of transmitting and receiving diseases from domestic animals or humans. As park visitor days increase and human demographic patterns change, shifts in patterns of human exposure to diseases carried by wildlife, including rabies, plague, and tick-borne infections, increase (Boyce et al. 1992). Basic research, monitoring, and surviellance programs should be implemented to document disease through serologic evaluation and identify parasitic infections of both native and exotic diseases and organisms in national parks of North America (Aguirre and Starkey 1994). Other needed health parameters include documenting introduced diseases and identifying disease vectors and related reservoirs, epizootics and emerging diseases, and the dynamics of disease within populations (Potts 1937; Oberhansley 1940; Nelson and Smith 1976; Jessup et al. 1981; Rabinowitz and Potgieter 1984; Pinter et al. 1988; Forrester 1990; Roelke 1990; New et al. 1993; Dunbar 1994; Aguirre et al. 1995a,b). Despite the identified need for health surveillance and monitoring, the national parks of North America have been reluctant to implement comprehensive wildlife health programs. The American Association of Zoo Veterinarians estimates that 225-250 full-time or part-time contract veterinarians are working in the 185 accredited zoos in the United States (W. Amand, personal commun. 2000). The USDA Animal Welfare Act of 1994 requires a that staff veterinarian monitor the health of zoological collections. The National Park Service manages 379 properties, including national lakeshores, preserves, recreation areas, seashores, wild and scenic rivers, and 55 parks (D. Barna, National Park Service, personal commun. 1999). Currently, there is only one recently hired (July 2000) full-time veterinarian to monitor wildlife health of national parks in the United States. Yellowstone National Park has contracted veterinary support for specific projects, and Parks Canada hires one veterinarian over a six-month period each year on a contract basis. Similarly, Parks Canada has hired veterinarians for specific research projects, including Wood Buffalo National Park, where veterinarians were hired as meat inspectors during the large-scale culls of wood bison conducted during the 1950s and 1960s. In recent times, several national parks in Canada have begun using the Canadian Cooperative Wildlife Health Centres at the four veterinary colleges in Canada (T. Shury, Parks Canada, personal commun. 2000). Health issues span taxa and disciplines. The park services must increase the capacity of their health-monitoring efforts. As the field of veterinary medicine expands into the environmental arena, it shares knowledge with an increasing number of conservation governmental and non-governmental agencies. Health professionals with clinical, epidemiology, and pathology skills will join biologists

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with backgrounds in ecology, conservation biology, biodiversity, and environmental ethics. This is where national parks, as laboratories of the natural world, will benefit most by integrating these professionals into wildlife programs using transdisciplinary approaches to problem solving. Veterinary schools are preparing wildlife health professionals for environmental challenges involving global issues, ecological health, and problems facing complex management systems such as those found in national parks. Several university programs are incorporating a variety of wildlife and environmental health opportunities beyond traditional medicine. One of the first programs was the Southeastern Cooperative Wildlife Disease Study formed by the Southeastern Association of Fish and Wildlife Agencies in 1957 based at University of Georgia School of Veterinary Medicine. This remains a leading organization on wildlife disease research. In 1997, Tufts University School of Veterinary Medicine, Wildlife Trust (formerly Wildlife Preservation Trust International), and Harvard University Center for Health and Global Environment partnered to establish the Center for Conservation Medicine. Loyola University Chicago Stritch School of Medicine and the Chicago Zoological Society/Brookfield Zoo, in association with the University of Illinois College of Veterinary Medicine, have established the Conservation Medicine Center of Chicago. Other institutions, including the University of California Davis School of Veterinary Medicine's, Wildlife Health Program and the North Carolina State University College of Veterinary Medicine's, Environmental Medicine Consortium, have joined these efforts. Wildlife health is an important part of environmental and public policy, as health of the environment is desired by both the ecologically aware public and natural resource management agencies. As we attempt to understand the role of interconnections in health, the continuum of life, and all processes within and outside a system, we begin to manage ecosystems, including those encompassing national parks, with an integrated approach involving wildlife and ecosystem health monitoring during the strategic planning of natural resources.

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