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DNA Tests Indicate Yellowstone National Park Elk, Not Bison, Most Likely To Spread Brucellosis


A study suggests that elk, not bison, are most likely behind the spread of brucellosis to livestock in states neighboring Yellowstone National Park. NPS photo.

While bison in Yellowstone National Park draw the most attention for the potential to spread brucellosis to livestock in the surrounding states of Montana, Idaho, and Wyoming, genetic studies indicate that elk are most likely behind the disease's spread in the region.

A small story in the fall issue of Yellowstone Science discusses that conclusion.

A DNA genotyping study conducted in 2009, and which was just recently published in the Journal of Wildlife Diseases, examined samples from 10 bison, 25 elk, and 23 cattle collected in the greater Yellowstone area between 1992 and 2003 and found that DNA markers for Brucella abortus were nearly identical in elk and cattle but "highly divergent" from those in bison.

"The data, which suggest that elk rather than bison are most likely the origin of recent outbreaks of brucellosis in Greater Yellowstone cattle, are consistent with the fact that elk comingle with cattle more often than do the wild bison, which have been managed to prevent dispersal outside established conservation areas," notes the Yellowstone Science article.

Some might not find that conclusion too surprising in light of the fact that there has never been a documented case in the wild of a bison transmitting the disease to cattle, while it has been seen with elk populations.

Brucellosis is a disease that can cause spontaneous abortions in livestock. The state of Montana currently is one of just two states that carry a "brucellosis-free" tag on their livestock industries. Losing that status can be costly, as it impacts the marketability of Montana cattle and ranchers must pay to test all their cattle for brucellosis.

As a result, Montana officials have been particularly aggressive about seeing that any bison that try to leave Yellowstone in spring are hazed back into the park after a certain date. Those hazing operations have at times drawn national attention due to injuries sometimes sustained by bison, and in part due to the efforts of the Buffalo Field Campaign, a non-profit activist group that works to illustrate the adverse treatment inflicted on some bison during hazing.

In an interview with the Traveler back in June, Dr. Marty Zaluski, the state veternarian for the Montana Department of Livestock, said that while there are efforts in his state to address brucellosis in elk and to prevent the spread of the disease from these ungulates -- efforts that range from keeping cattle and elk separate during calving seasons and even "strategic hunting" -- the high-profile debate over bison stems in large part from the efforts of the Buffalo Field Campaign.

"And not only that, but bison are so photogenic and people of the United States feel such an attachment of tradition and history to bison that really, bison typically hog, I shouldn’t say hog, but certainly get a lot of the media attention," Dr. Zaluski added at the time.

Yellowstone officials currently are writing an environmental impact statement on a proposal to vaccinate bison against brucellosis.

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Excellent dialogue, story. Thank you. One aspect of this issue that should consistently be discussed are the elk feeding grounds within the Greater Yellowstone Ecosystem, in Wyoming and Idaho. These artificial feeding stations are a huge culprit in the spread of disease. Shut down, phase out the feed grounds, and brucellosis becomes even more of a non-issue. What a no-brainer! We are constantly told "don't feed the wildlife" but there goes the federal and state governments, doing just that, only to appease livestock interests. They perpetuate their own problems and underscore their selfish intentions.

And it cannot be repeated enough that this country's wildlife, including elk and buffalo, got brucellosis from cattle. As to buffalo, there has never been a documented case of wild bison transmitting this disease back to livestock, even where they co-exist. This is a livestock disease that came to North America with Euro-Asian cattle. Bison have an incredible immunity to the disease and develop antibodies once exposed. These antibodies, unfortunately, are the very thing that the current bison mismanagement scheme looks for and sends buffalo to slaughter for having. If a buffalo has antibodies, its test will come up blood (sero) positive, and that strong, immune bison will be sent to slaughter. The Interagency Bison (mis)Management Plan is in the business of killing off the strong buffalo, and trying to disrupt their natural migratory behaviors. Shame shame shame.

As to elk in Montana, "special" hunting seasons are being put in place just to cater to ranchers concerns. So sadly funny how the same voices cry "the wolves are killing all the elk" and then say "there's too many elk and they're eating the grass!" How about the concerns of wildlife and wild lands? How about the millions of miles of barbed wire and numerous diseases that come with livestock production? How about managing the manageable element.... cattle.

It's a simple manner of ranchers taking responsibility for the impacts their business has on everything else. Manage livestock and so many problems go away. Remove cattle from public lands, and so many problems go away. We must insist that our nation's native wildlife are free to roam, reclaim their stolen lands, and help restore habitat.

This issue, the deeper one delves into it, is clearly about the grass and who gets to eat it rather than disease. There is one common problem in any debate about wolves, elk, buffalo, bears..... cattle. One element causing so much trouble. Livestock production is a cruel and unhealthy industry, heavily subsidized by U.S. taxpayers, with an enormous burden placed upon native flora and fauna. The solution is really clear and simple: remove cattle, problems solved.

That is a stupid comment and will never happen. Why do people say stupid (stuff) like that.


Thanks for covering this story. The key to this issue is to manage the cattle. Vaccinating bison and/or elk will be a big waste of time and money so please keep a close eye on the ill-advised proposal by Yellowstone National Park to "remotely" vaccinate bison with an ineffective vaccine. I submitted extensive comments on this proposal on behalf of the Gallatin Wildlife Association in Bozeman Montana and I would be happy to share them with you or any of your readers. YNP has outlined in their draft Environmental Impact Statement that this vaccination proposal would last 30 years, cost taxpayers at least $9 million dollars (an extremely optimistic estimate) and wouldn't buy the bison one more ounce of tolerance from the livestock industry because there would still be brucellosis present in bison. And, of course the proposal ignores elk. YNP shouldn't be poking, harrassing, capturing and slaughter our wildlife. Manage a few cows reasonably and let our wildlife be wild. Everyone interested in this issue should contact YNP and tell them to stand down.


I may be wrong, but when it comes to sample size in a test of this nature (looking at genetic variation) you don't need a large sample. In fact, DNA evidence that is submitted in court often compares only two samples (one from the evidence collected and one from the suspect). This type of study is not looking to produce an average or some other statistical test, which would require a large sample, it is looking for a match.

I still say, dump the cattle and raise bison. The meat is tasty and better for you. After all the bison is America's cattle. The bison is well adapted to the environment of the American plains. We really do not need European cattle.

Damn! What a sample size to conclude that elk, not bison, are the source of infection for cattle. You can also read about more trials that were done, ten, twenty, thirty, forty, and even fifty years ago that say the same thing as the trials that they conduct each year. Just goes to show how the dollars are being spent. While they write the vaccination proposal, they have no clue to how the immune system of the bison works. When given the opportunity to solve the problem of brucellosis, they refuse to seek the advice of the real experts. Good Luck!

Kind of distills the issue of livestock versus wildlife. The notion that ranching and healthy native ecosystems can comfortably coexist comes into question over this issue. So, which do you prefer to dominate the Greater Yellowstone?

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