Ranchers, officials uneasy about brucellosis
by nathan oster
Officials from the Wyoming State Livestock Board urged local cattle producers to be proactive in monitoring their herds for brucellosis following the recent announcement from the Game and Fish Department that two elk taken in the Big Horn Mountain had tested positive for the bacteria.
“If I was a producer in this area, I would want to get some surveillance testing in my cattle herd to assure myself that it wasn’t there — or to find it quickly if it was,” said Dr. Jim Logan, the state veterinarian. “If you go through the calving seasons with one infected female that calves in your herd, you will know it the next year.
“The longer you wait to find it, the greater the risk of inter-herd spread.”
Logan was one of several Wyoming Livestock Board and Wyoming Game and Fish officials in attendance at a public meeting Thursday night at the Greybull Elks Lodge attended by approximately 50 local producers.
While Logan’s call was for livestock producers to be proactive, even he acknowledged early in the evening that no one yet knows what to make of the two positive tests, which was discovered in elk taken in Hunt Area 40.
Alan Osterland, a G&F regional wildlife supervisor, said one of the positives came back on a cow elk taken Oct. 16 on Bald Mountain, while the other was from a bull elk taken Oct. 18 in the Bear Creek drainage.
“There are a lot of things at this point that we do not know about this situation,” said Logan. “We don’t expect there are cattle infected, but factually, we don’t know. We certainly hope there aren’t. But other states are willing to give us time to get the facts found — and that’s what we’re doing.
“Finding two elk that tested positive on the blood test does not mean those elk are infected. “A lot of things could be going on. Those elk could be infected, or they could have been exposed to the bacteria and have antibodies in their system, or it could be from a cross infection with other bacteria. There’s a lot we don’t know.”
Logan said he has no intention of recommending an enlargement of the designated brucellosis surveillance area (DSA) to include Big Horn and Sheridan counties. In 2010, the boundaries of that DSA were expanded and it now includes all or parts of Park, Teton, Sublette, Fremont and Sweetwater counties.
“Within that surveillance area, we have had over the years quite a few cases in cattle,” Logan said.
Terry Kreiger, a G&F veterinarian, said the two positive tests in the Big Horns were the first two since the G&F started monitoring for brucellosis statewide in the 1990s.
Brucellosis, or brucella abortus, is a European-based disease that was originally brought into the Greater Yellowstone area by bison. It affects not only bison but also elk and cattle by causing females to abort their calves.
Brucellosis is spread orally when an infected cow gives birth. According to Kreiger, its fetus is full of infectious bacteria, and other animals pick it up when they lick or smell the infected fetus — or in some cases, a live calf that is born with it.
In 1934, a program was developd to eliminated brucellosis from domestic cattle.
Today all 50 states are classified as “brucellosis free” in domestic cattle, but according to the G&F presentation, infected elk and bison in the greater Yellowstone area are “a constant threat.”
Kreiger said 61 percent of infected elk abort their first calf and 10 to 20 percent will abort their second and third calves as well. But overall calf loss in a free-ranging, infected population is 10 percent. The incubation period (contact to aborted) is generally three months, and most abortions in elk occur between February and June, Kreiger said.
The G&F extensively monitors for brucellosis inside the DSA, but focuses on different parts of the state each hunting season by providing test kits to limited-quota hunters, who are asked to collect blood samples from their kills and send them into the state lab for testing.
After the meeting, Kreiger said that prior to 2012, the last time the Big Horns were a focus of the surveillance efforts was approximately 2008. Prior to that, it was 2004. “Every three to four years,” he said.
Thousands of samples arrive in the state lab each year — and after employees there get done testing for chronic wasting disease, which takes priority, the focus then shifts to the brucellosis samples, Kreiger said. Of all the elk samples that were sent in by hunters in the Big Horns in 2012, just 22 were “suitable for testing,” he said.
Osterland said the elk herd in the Big Horn Mountains, which is managed by G&F personnel in Sheridan and Cody, is actually above its population objective of 4,500. In fact, some longer hunting seasons are proposed for this year in the hopes of thinning the herd.
In hunt area 40, the objective is 850 elk; the three-year population average has been 873.
Osterland said the G&F will increase its surveillance efforts in hunt area 40 not only this year but also in the next few years to come. “We want to see an increase in the usable sample size,” he said, adding that hunters should expect more check stations. “And we will also increase our efforts to document elk distribution.”
Logan said that among cattle, infected animals should be considered “lifelong carriers” and that heifers and pregnant animals are “most susceptible.” Older animals tend to be more resistant, but that isn’t a given, either. “In all the herds where we’ve had it, we’ve had a mixture of some old ones and some young ones. It can hit any age.”
Logan told producers that live calves can be born to brucellosis-infected animals, but that they “are born weak, they are unthrifty and they show signs similar to pneumonia. Generally they die within two to three days of birth.”
The most common clinical sign of a brucellosis-infected animal is the abortion of its first calf, and Logan said animals “may go on to have normal, live calves in future years.” However, “That isn’t a reality in the cattle world,” he said. “Once a female cow is found in a herd, it is generally culled from the herd.” That’s because brucellosis is a “community disease,” meaning that an infected animal has the potential to infect every other animal in the herd.
So how can it be prevented? Logan cited four “tools” or approaches:
• Temporal or spatial separation. “As producers in an area where there may be infections, I encourage you to take precautions,” said Logan.
• Good management. “If it happens to be in your herd, you want to find it as quickly as possible.”
• Surveillance. “In the DSAs we have surveillance requirements and it’s helped us find several cases,” he said. “People in this area, unless they happen to run cattle in the DSA, most haven’t had to worry about surveillance of that type.”
• Vaccination of calves and adults. “It’s not 100 percent effective, however,” he said.
Logan said brucellosis has a public health significance as well. “People can get it too,” he said, adding that ranchers and sportsmen are most susceptible. It is primarily transferred to humans via contact with an infected fetus or through unpasteurized milk.
The states of Wyoming, Idaho and Montana are considered to be “the last known reservoir of brucella abortus in wildlife in the U.S. — and Logan said an outbreak could have devastating effects on the local cattle industry.
“In spite of Wyoming being classified brucellosis-free, other states do have concerns about our wildlife reservoir,” Logan said. “They are concerned about buying cattle. They have been good to Wyoming because of our efforts in the DSA.
“But this situation has raised eyebrows. Other states have been patient. But we are going to have to show them some action that we are taking to make sure it hasn’t spilled outside the DSA. It’s a real significant thing as far as marketability goes.”
Logan said Idaho doesn’t have as good a surveillance program as Wyoming and that it resulted in sanctions from North Dakota. Other states may follow suit, Logan said. “We have to do something outside of the DSA to show these other states that we’re serious. We need to make sure we are providing a clean product when our cattle leave the state.”
Bob Meyer, assistant state veterinarian, said animals are tested in Wyoming at slaughter, in their first point of concentration (i.e., when they go to market) and when producers request direct-herd testing, which involves entering into a herd plan with the state.
State livestock officials urged ranchers to strongly consider the herd plan option and added that they are trying to find funding sources to pay for brucellosis surveillance testing outside the DSA.
“Get a risk assessment done,” Logan said. “For your own protection, but also to protect your marketability. If we don’t do anything outside the DSA for surveillance work, other states may say we need to put tests in place. We don’t want this to put us in a vulnerable position.”