Testing Reveals Increase in Brucellosis Prevalence in Madison EMU

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Results from hunter harvest surveys and Montana Fish, Wildlife and Parks (FWP) capture and collaring operations this winter show an increased rate of brucellosis prevalence in the Madison Elk Management Unit (EMU).

 

Testing from the 2004-2005 season indicates a 6.9% seroprevalence rate of brucellosis in elk in the Madison EMU, up from 4.9% during the previous sample year of 2002-2003. A positive seroprevalence means that an animal has been exposed to the brucella bacteria at some time, but it is not evidence that an animal is currently infected or actively shedding the bacteria. The serologic evidence for exposure to brucellosis as determined from blood samples should not be confused with infection rates, which based on previous elk research, may be as low as 1 to 2% of the elk from this area.

 

“Brucellosis rates in the Madison Elk Management Unit have fluctuated within acceptable limits (below 5%) over the years, but we have seen a slight increase in prevalence in the last sampling period that we want to investigate further,” said Kurt Alt, FWP Region 3 Wildlife Manager.

 

“Although the seroprevalence appears to have increased slightly in the last two sample years in the Madison EMU, it remains relatively low and is similar to the seroprevalence found in elk that do not use feedgrounds in Wyoming and Idaho. It is substantially lower than the seroprevalence in elk using feedgrounds in those states,” Alt added. FWP has tested 26 different elk herds in Montana since 1980 and found brucellosis only in elk from the Greater Yellowstone Area.

 

In accordance with the Montana Brucellosis-Elk Management Plan , because brucellosis rates have risen above 5%, FWP will assemble a review team to complete an analysis of the factors controlling the presence of the disease and assess the need for additional surveillance. The review team will be made up of wildlife biologists, veterinarians, epidemiologists, and other officials from Montana Fish, Wildlife and Parks, Department of Livestock, and USDA Animal and Plant Health Inspection Service.

 

“Although this is not welcome news, we are well-positioned to address the issue,” said Alt. Extensive surveillance and more consistent protocols were established in the Madison EMU in the early 1990s. And, prior to these recent test results, FWP initiated a research study to evaluate and assess the risk potential of brucellosis transmission between elk and cattle in the upper Madison. The study is ongoing for the next several years.

 

“We’re also fortunate that there is an organized landowner/sportsmen working group in the Madison Valley that is addressing complex elk and livestock issues,” said Craig Jourdonnais, FWP Madison-Gallatin Wildlife Biologist. “Their input on this issue will be very important.”

 

A public presentation and discussion will be held in the Madison Valley to answer questions and address concerns. The meeting time and location will be announced in the near future.