Brucellosis battle

Posted

Brucellosis confirmed in Park County cattle herd

Brucellosis has jumped the fence and infected a Park County cow. 

The herd was quarantined on Nov. 10, and results for one cow came back positive from the Wyoming State Veterinary Laboratory in Laramie on Nov. 19. A positive blood test also was confirmed at the National Veterinary Services Laboratory in Ames, Iowa.

In recent years, brucellosis has been found in Park, Teton and Sublette counties, said Wyoming State Veterinarian Dr. Jim Logan. Before Wyoming went brucellosis class free in 1985, the disease was found all over the state. All confirmed cases of infection have been isolated to northwestern Wyoming since 1985, mostly because that is where the most elk are located, he said.

“It is important to note that in the Greater Yellowstone states we are the only reservoir where the disease exists in the country,” Logan said, noting that all other states have been declared brucellosis-free. “We worry about the wild elk and bison in Yellowstone and Teton and within our surveillance area in Montana, Idaho and Wyoming.”

Northwestern Wyoming has a reservoir of brucellosis in wildlife that sometimes infects local cattle, Logan said. Right now, it is unknown if the infection was caused from elk exposure, like the rest of the infection cases in the area had been from 2003-11.

“We expect that will be the case, but do not have proof of that yet,” Logan said. “Ranchers have to be pretty vigilant of keeping cattle away from elk.”

It’s hard to say if brucellosis will ever be eradicated from the area like it has been for the rest of the country.

“We have such big populations of elk in the area, and once it's in a wildlife population it is difficult to get rid of them,” Logan said.

Epidemiological tracing is being done by the herd owners, personnel from the livestock board and private veterinarians. The initial response should wrap up before December, and follow-up testing is slated for the following months, Logan said.

Even though the brucellosis vaccine is required for all of Wyoming’s heifers, it is still possible for livestock to get infected. Complications with the immune system are a likely factor for whether or not the vaccine takes effect, Logan said.

“The vaccine is not 100 percent efficacious, as is any vaccine, like measles in kids or rabies in dogs,” Logan said. “It prevents the problem in a certain percentage — 60-70 percent, which is pretty good.”

Although it is possible for humans to get infected with brucellosis, it is extremely rare, according to the Centers of Disease Control and Prevention.

“For the average person, it doesn’t mean much of anything really — it certainly matters to the cattle industry and the producer who owns the herd that is under quarantine,” Logan said. “It is not a food-safety issue. It is strictly an issue of the cattle herd it has been found in.”

The herd’s owner should be fine too, as the herd’s heifers and steers can be sold once they come out of quarantine.

“It is never convenient, but if there is a better time it is winter because the ones that were going to be sold have left the herd,” Logan said. “It won’t upset marketing strategies drastically, but there are worse times of the year to be under quarantine.”  

The owner of the herd was not identified, but the herd was located around the middle to southwestern portion of Park County, Logan said.

The infected cow’s herd will remain quarantined until the entire herd has three consecutive negative results and all infected cattle are removed, according to the Wyoming Livestock Board. An additional contact herd is also quarantined for testing.

“It is disappointing to find it, but it is not a great big surprise and we suspect from time to time we will find elk exposure where the disease has been spread into wildlife and cattle,” Logan said. “The key thing is our system is good for surveying, and it has found the disease before there has been a lot of spread — or any spread — from one herd to another. Our rules and system work to keep us protected from other states imposing sanctions on our herds when they are marketed.”

The livestock board’s veterinarians also are investigating a potential brucellosis case in Sublette County. Tissue culture results are not in yet, so the herd has not been officially designated as infected.

For more information, contact Logan at 307-857-4140 or 307-421-1682.

Although no formal decision has been reached to manage bison leaving Yellowstone National Park in search of food in winter and spring, options exist to sidestep slaughtering the iconic creatures.

The concern is that bison could infect cattle with brucellosis.

A decision by the eight members of the Interagency Bison Management Plan (IBMP) as to the fate of the migrating bison has not been reached yet.

The IBMP was signed in December 2000 to coordinate bison management between the state of Montana and Yellowstone National Park.

Every year, approximately 1,000 bison need to be culled, said Sandra Snell-Dobert,

Yellowstone National Park Public Affairs Office.

The IBMP group met to discuss winter operations for 2015/16 on Nov. 20. Members agreed that the bison population must be reduced and that tribal and public hunting outside the park is the preferred method to reach that goal, according to the National Park Service. Capture and shipment to meat processing facilities is used when hunting outside the park doesn’t reach objectives of a 5-10 percent decrease. “Negotiations about details will continue between the partners over the next few weeks,” the Park Service said.

A final decision will be reached in mid-December, Snell-Dobert said. “The 1,000 could change depending on what other partners in the bison committee come back with.”

“We’re definitely having hunting going on this winter,” Snell-Dobert said. In fact, Native Americans are hunting bison now. “Beyond that, we just don’t have any numbers.”

The target population is 3,000 bison within the park. Since 2000, the population has averaged 4,000. At this time there are probably between 4,000-4,500, Snell-Dobert said.

The issue isn’t lack of bison habitat in the park. The issue is bison leaving the park to potentially infect cattle with brucellosis and cause property damage such as smashing fences, Snell-Dobert said.

Wild bison are only allowed in limited areas outside of Yellowstone because some are infected with brucellosis that can be transmitted to cattle, according to the National Park Service.

Bison aren’t the only animals that carry brucellosis. Elk have it too, Snell-Dobert said.

No bison have infected Montana cattle with brucellosis, said Matt Skoglund, director of the Northern Rockies Bozeman, Montana office of the Natural Resources Defense Council (NRDC).

Elk that migrate in and out of the park are a part of the established hunting practices around Yellowstone, Snell-Dobert said. Elk are a commercial draw to the area. Bison are not. Bison might enjoy greater tolerance outside Yellowstone in Montana if they were included in the regular hunting seasons as elk are. But first, bison must be tolerated outside Yellowstone before more hunting seasons can be developed.

People around the park coexist with bears, wolves, deer, etc. “We want to see bison from Yellowstone treated like other wildlife in Montana,” Skoglund said — allow tribal hunting and have Montana, Fish Wildlife & Parks manage bison outside Yellowstone like other big game animals.

It would be possible to issue more bison licenses, said Ron Aasheim, Montana Fish Wildlife and Park Communication & Education Division administrator in Helena, Montana. Last year, Native Americans took around 200 bison.

There are bison tolerance zones outside the park in Montana, Aasheim said.

Adjacent to the North is the Gardiner Basin & Eagle/Bear Creek comprising 104,000 acres. There are 37,870 acres adjacent to the West Gate with another 279,950 acres under consideration, according to Wildlife & Parks.

Since 2011, the Bison Coexistence Fencing Project in partnership with the NRDC, Greater Yellowstone Coalition, Sierra Club and Defenders of Wildlife has built fences to prevent bison intruding on landowner property in the Gardiner and West Yellowstone, Montana, areas, Skoglund said. “It’s been a very successful project.”

Recovery and rebuff

In 1902, after years of market hunting and poaching, only about two dozen bison were left in Yellowstone. “The next 100 years chronicled the slow, but determined efforts of dedicated people to bring this species back from the brink of extinction,” according to the Park Service.

“Yellowstone’s iconic wild bison are central to the long-term conservation of the species, as they are a large population and the only continuously wild and free-roaming population in the U.S.,” Skoglund said.

Yellowstone bison are the only free ranging herd, Snell-Dobert said. “That just doesn’t exist anywhere else.”

“It really is time to provide year-round habitat for bison outside the park,” Skoglund said.

“There are political realities we’re dealing with here. It’s such a complicated issue,” Snell-Dobert said. “There are no easy answers.”

Brucellosis is a contagious disease of ruminant animals such as cattle and bison that can affect humans. The main threat is to cattle, bison, swine and cervids, such as elk and deer, according to the U.S. Department of Agriculture.

The disease is also known as contagious abortion, as it can cause miscarriage in animals. For humans, symptoms include a severe intermittent fever.

In 2014, there were 92 confirmed cases of brucellosis infection in American citizens according to the Mayo Clinic. Although classified as “very rare,” human infection from animals to people mostly occurs through unpasteurized dairy products and is treatable. Contact with infected animals may also lead to an infection for humans, according to the Centers for Disease Control and Prevention.

Comments