Initial Testing Reveals Exposure to Brucellosis in Elk in the Ruby Valley, Montana

Initial testing for brucellosis in elk in the Ruby Valley area west of the Gravelly Mountains near the Blacktail Wildlife Management Area reveals that some elk have been exposed to the disease.

Montana Fish, Wildlife & Parks’ wildlife laboratory supervisor Neil Anderson said 12 of 100 elk tested positive for exposure to brucellosis based on initial screening. The blood testing only indicates if an animal has been exposed to the disease and does not mean the animals is necessarily infected and can spread the disease.

The capture is part of a five-year study to help refine the state’s approach to managing the risk brucellosis-exposed elk pose to livestock and focuses on fringe areas of previous brucellosis surveys. FWP captured the elk in early February, the first year of a five-year study, to better understand and manage the risk of brucellosis transmission in Montana, answer questions related to brucellosis prevalence, and evaluate several common brucellosis testing methods that have produced inconsistent exposure-rate results.

“The study will attempt to determine if a brucellosis-positive cow elk aborts and if a cow elk that aborts in one year continues to do so or if it occurs primarily with the first pregnancy,” said FWP Wildlife Bureau Chief Ken McDonald. “In addition, the study will attempt to determine if elk that test positive in one year continue to do so in succeeding years.”

The elk were tested in the field for exposure to brucellosis using one type of test. All of the blood samples were then sent to the Montana Department of Livestock Diagnostic Laboratory for further testing using a full panel of additional brucellosis tests.

The samples that tested positive on the full panel of tests will be sent to a laboratory at Louisiana State University for an additional test to determine if false positive results may have occurred. Actual brucellosis exposure is expected to be within the range of results from all of the different tests and less than 12 percent as indicated in initial testing. Results from the Louisiana State University laboratory are not expected for a month or more.

In order to better understand elk movements and distribution relative to disease transmission risk, researchers will follow thirty GPS-radio collared elk throughout the year to determine seasonal movement patterns and interactions with other elk and livestock. Elk that test and remain positive for exposure to brucellosis for five years will be removed from the population for further study to confirm actual brucellosis infection.

“It’s unfortunate that the preliminary results indicate some brucellosis exposure in elk in this area,” said State Veterinarian Dr. Marty Zaluski. “I appreciate FWP’s efforts to better understand the distribution of the disease in elk to better manage risk.”

Over the course of five years, crews will capture 100 elk in a different area each year. The effort will be replicated in four other areas between 2012 and 2015 if sufficient funding and collaboration with landowners can be secured. The study is estimated to cost about $300,000 each year.

– From FWP wire services
fwp.mt.gov