Feasibility of quarantine procedures for bison (Bison bison) calves from Yellowstone National Park for conservation of brucellosis-free bison.

OBJECTIVE--To determine the feasibility of qualifying individuals or groups of Yellowstone National Park bison as free from brucellosis. DESIGN--Cohort study. SAMPLE--Serum, blood, and various samples from live bison and tissues taken at necropsy from 214 bison over 7 years. PROCEDURES--Blood was collected from bison every 30 to 45 days for serologic tests and microbiological culture of blood for Brucella abortus. Seropositive bison were euthanized until all remaining bison had 2 consecutive negative test results. Half the seronegative bison were randomly euthanized, and tissues were collected for bacteriologic culture. The remaining seronegative bison were bred, and blood was tested at least twice per year. Cow-calf pairs were sampled immediately after calving and 6 months after calving for evidence of B abortus. RESULTS--Post-enrollment serial testing for B abortus antibodies revealed no bison that seroconverted after 205 days (first cohort) and 180 days (second cohort). During initial serial testing, 85% of bison seroconverted within 120 days after removal from the infected population. Brucella abortus was not cultured from any euthanized seronegative bison (0/88). After parturition, no cows or calves had a positive test result for B abortus antibodies, nor was B abortus cultured from any samples. CONCLUSIONS AND CLINICAL RELEVANCE--Results suggested it is feasible to qualify brucellosis-free bison from an infected herd following quarantine procedures as published in the USDA APHIS brucellosis eradication uniform methods and rules. Latent infection was not detected in this sample of bison when applying the USDA APHIS quarantine protocol.

A Review of Hypothesized Determinants Associated with Bighorn Sheep (Ovis canadensis) Die-Offs.

Multiple determinants have been hypothesized to cause or favor disease outbreaks among free-ranging bighorn sheep (Ovis canadensis) populations. This paper considered direct and indirect causes of mortality, as well as potential interactions among proposed environmental, host, and agent determinants of disease. A clear, invariant relationship between a single agent and field outbreaks has not yet been documented, in part due to methodological limitations and practical challenges associated with developing rigorous study designs. Therefore, although there is a need to develop predictive models for outbreaks and validated mitigation strategies, uncertainty remains as to whether outbreaks are due to endemic or recently introduced agents. Consequently, absence of established and universal explanations for outbreaks contributes to conflict among wildlife and livestock stakeholders over land use and management practices. This example illustrates the challenge of developing comprehensive models for understanding and managing wildlife diseases in complex biological and sociological environments.

Shared Bacterial and Viral Respiratory Agents in Bighorn Sheep (Ovis canadensis), Domestic Sheep (Ovis aries), and Goats (Capra hircus) in Montana.

Transmission of infectious agents from livestock reservoirs has been hypothesized to cause respiratory disease outbreaks in bighorn sheep (Ovis canadensis), and land management policies intended to limit this transmission have proven controversial. This cross-sectional study compares the infectious agents present in multiple populations of bighorn sheep near to and distant from their interface with domestic sheep (O. aries) and domestic goat (Capra hircus) and provides critical baseline information needed for interpretations of cross-species transmission risks. Bighorn sheep and livestock shared exposure to Pasteurellaceae, viral, and endoparasite agents. In contrast, although the impact is uncertain, Mycoplasma sp. was isolated from livestock but not bighorn sheep. These results may be the result of historic cross-species transmission of agents that has resulted in a mosaic of endemic and exotic agents. Future work using longitudinal and multiple population comparisons is needed to rigorously establish the risk of outbreaks from cross-species transmission of infectious agents.

Pathogenesis and epidemiology of brucellosis in yellowstone bison: serologic and culture results from adult females and their progeny.

Our objective in this prospective study was to determine the natural course of Brucella abortus infection in cohorts of seropositive and seronegative, female bison (Bison bison) and their offspring in Yellowstone National Park (YNP) for 5 yr. We collected specimens from 53 adult females and 25 calves at least once and from 45 adults and 22 calves more than once. Annual seroconversion rates (negative to positive) were relatively high (23% for calves and juvenile bison, 6% in the total sample of adult female bison in our study, and 11% in the adult females that began the study as seronegatives). Antibody was not protective against infection, even for calves that passively received antibody from an infected mother's colostrum. Antibody levels stayed remarkably constant, with only a slow decline over time. We found only two seroconversions from a weak positive status to negative. Infected bison aborted and shed viable bacteria. Risk of shedding infective Brucella was highest for bison in the 2 yr following seroconversion from negative to positive. In one bison, we detected shedding for 3 yr following seroconversion. Regardless of serostatus of dams and neonates, most calves were seronegative by 5 mo of age. There was no relationship between the antibody status of the dam and the tendency of a calf to seroconvert to positive during the duration of the study.

The ecological future of the North American bison: conceiving long-term, large-scale conservation of wildlife.

Many wide-ranging mammal species have experienced significant declines over the last 200 years; restoring these species will require long-term, large-scale recovery efforts. We highlight 5 attributes of a recent range-wide vision-setting exercise for ecological recovery of the North American bison (Bison bison) that are broadly applicable to other species and restoration targets. The result of the exercise, the "Vermejo Statement" on bison restoration, is explicitly (1) large scale, (2) long term, (3) inclusive, (4) fulfilling of different values, and (5) ambitious. It reads, in part, "Over the next century, the ecological recovery of the North American bison will occur when multiple large herds move freely across extensive landscapes within all major habitats of their historic range, interacting in ecologically significant ways with the fullest possible set of other native species, and inspiring, sustaining and connecting human cultures." We refined the vision into a scorecard that illustrates how individual bison herds can contribute to the vision. We also developed a set of maps and analyzed the current and potential future distributions of bison on the basis of expert assessment. Although more than 500,000 bison exist in North America today, we estimated they occupy <1% of their historical range and in no place express the full range of ecological and social values of previous times. By formulating an inclusive, affirmative, and specific vision through consultation with a wide range of stakeholders, we hope to provide a foundation for conservation of bison, and other wide-ranging species, over the next 100 years.