Bison quarantine removes threat of brucellosis

Bison quarantine removes threat of brucellosis

Quarantine protocol successfully used to qualify brucellosis-free bison from infected herds.

A NEW study from the U.S. Department of Agriculture's Animal & Plant Health Inspection Service (APHIS) and the Wildlife Conservation Society (WCS) demonstrated that it is possible to qualify bison coming from an infected herd as free of brucellosis using quarantine procedures.

These bison can then be used to seed conservation herds in other landscapes without the threat of spreading the disease.

In response to Interagency Bison Management Plan (IBMP) guidelines on federal and state bison management actions, the APHIS Brucellosis Eradication: Uniform Methods & Rules (UM&R) protocol for the quarantine of bison was tested to see if it could successfully be used to qualify the animals as brucellosis free.

Results of the study indicated that it is feasible to take young bison from an infected population and, using the approved quarantine protocol published as a federal UM&R, qualify them as brucellosis free in less than three years.

Between 2005 and 2008, more than 200 bison calves of Yellowstone National Park origin were transported to a quarantine facility at Corwin Springs, Mont., just outside Yellowstone.

During the study, blood samples were collected from the animals every 30-45 days and tested for brucellosis. Those animals that tested positive were euthanized, and those remaining were tested until all had two consecutive negative tests.

Since the primary mode of brucellosis transmission is via abortion and birthing events, all animals testing negative were held until they produced their first calf and showed no evidence of the disease in newborn calves, birth fluids or blood, an announcement said.

At that point, the bison were considered brucellosis free. The study showed that all bison continued to be brucellosis free over the course of the seven-year study, after the initial screening period and through several calving cycles. No evidence of brucellosis was found in either newborn calves or their mothers.

"The results of this study indicate that under the right conditions, there is an opportunity to produce live brucellosis-free bison from even a herd with a large number of infected animals like the one in Yellowstone National Park," APHIS veterinary officer Dr. Jack Rhyan said. "Additionally, this study was a great example of the benefits to be gained from several agencies pooling resources and expertise to research the critical issue of brucellosis in wildlife."

The authors of the study noted that agencies charged with bison management agree that capture and relocation of bison to other suitable habitats would be an appropriate alternative to the lethal removal of bison that exceed population objectives for Yellowstone National Park, as defined by the IBMP. The UM&R protocol could facilitate such relocation by demonstrating that animals are disease free and would not transmit brucellosis to cattle or other animals, they said.

At the same time, a movement to ecologically restore bison to large landscapes is gaining momentum throughout the U.S. and Canada, and brucellosis-free bison may be needed to seed those landscapes. In particular, the genetics of Yellowstone bison are important because they are known to be free of cattle genes and represent bison that existed on the Great Plains for thousands of years.

WCS bison project coordinator Keith Aune said, "This study represents an important milestone in bison conservation, and these research findings enable us to practice genetic rescue from brucellosis-infected bison herds. The Yellowstone animals passing through this system of testing are critical to conserving the diversity of the bison genome over the long term.

"We've also learned a great deal about brucellosis blood testing and how to better interpret results when screening animals for this disease. It is our hope that several satellite herds of Yellowstone bison can be assembled from the animals that graduate through this quarantine process," Aune added.

The study, "Feasibility of Quarantine Procedures of Bison (Bison bison) Calves from Yellowstone National Park for Conservation of Brucellosis-Free Bison," appeared in the March 1 edition of the Journal of the American Veterinary Medical Assn.

Funding for this study was provided by APHIS, Montana Fish, Wildlife & Parks and the Montana Department of Livestock.

Volume:86 Issue:10

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