BCT considers feedgrounds’ risk assessmentsWritten by Joy Ufford
Pinedale – Wyoming’s Brucellosis Coordination Team (BCT) discussed a number of possible means to reduce the disease’s transmission between elk and cattle at its April 13 meeting in Pinedale.
Research projects, affected herd updates, budget crunches and new data were shared by Wyoming, Montana and Idaho agencies, and the daylong meeting closed with a call for the BCT to move forward.
Studies and updates
Montana State Vet Eric Liske presented study updates, as did its wildlife agency, and Wyoming Game and Fish Department (WGFD) biologists presented data from elk hunters’ surveillance and GPS studies in Wyoming.
A research project led by University of Wyoming’s Noah Hull brought exciting news that a test is getting closer to being able to distinguish former vaccine Strain 19 titers from the actual disease.
Strain 19 was found to be very effective for cattle but also produced “false positives” in blood tests, so it was dropped. Finding a reliable vaccine and improved tests are high on the list of accomplishments the BCT encouraged.
A top recommendation from the Governor’s Brucellosis Coordination Team was for WGFD to update its brucellosis management action plans (BMAPs), according to WGFD Brucellosis Program Supervisor Brandon Scurlock, who released the top 10 at a public meeting March 24 in Pinedale.
“We met with producers and partners in late December and asked how to better reduce transmission from elk to cattle and elk to elk,” he said.
Those comments were integrated into the BMAPs that Scurlock presented at the BCT’s April 13 meeting in Pinedale.
The 10 elements are feedground locations, elk population reduction, feedground phase-out, reducing feed season length, habitat enhancement, fencing, acquisitions and easements, test and slaughter, vaccine investigation and mapping areas of brucellosis risk.
Infected cow elk miscarriages or abortions peak in March, April and May, which overlaps with concentrated elk feeding to keep elk from mixing with livestock. At several feedgrounds, seasons are shortened and hay is scattered for low-density feeding. Another tool is allowing scavengers to clean up the feedgrounds.
Elk are traditionally fed on one or two long lines that create hotspots for brucellosis transmission, he said. Fed farther apart in a checkerboard pattern, studies show elk contact with fetuses can drop by 75 percent. However, some sites are not suited for change.
Moving feedgrounds could influence behavioral changes and reduce transmission risks. However, brucellosis would still persist.
Feedground phase-out could increase elk-to-cattle brucellosis transmission in the long run, he said. Starting to feed late or ending early might reduce transmission, be fairly cost-effective and keep elk population objectives, or it might increase commingling during prime transmission.
The Dell Creek and McNeel feedgrounds near Bondurant aren’t managed for end dates due to adjacent livestock herds.
Habitat enhancement could reduce seroprevalence where elk have access to more forage. Land acquisition, easements and fencing secure habitat and reduce commingling but are expensive and rely on landowners’ cooperation.
Test and slaughter, used from 2006 to 2010 to slaughter elk testing seropositive for brucellosis, worked until several years after it ended, but then seroprevalence spiked again.
New vaccines, vaccine delivery, better field tests and contraceptives are always under study.
The BMAP’s final action suggests mapping brucellosis risk. The BCT asked WGFD to update feedground herds’ seasonal ranges and GPS data showing biologists where elk are during major brucellosis transmission season could be used to make risk maps.
Bousman suggested different BMAP tools might reduce transmission risks at feedgrounds near cattle producers.
Sommers agreed, saying, “Everyone’s situation is different.”
After Scurlock shared draft BMAPs, the BCT board discussed them at length. He noted difficulties with phasing out feedgrounds and said this is the first winter WGFD did not vaccinate elk with Strain 19.
Scurlock’s data-driven map of GPS locations for elk in February through June and March through May could be used for “risk assessment maps” for land managers, producers and agencies. The draft will be finalized by the BCT’s November meeting.
“I fully believe we need to look at risk assessment,” Sommers said. “If we look at feedgrounds, a handful are probably higher risk than others.”
BCT member Terry Pollard stated, many feel closing elk feedgrounds would have “devastating effects on a lot of people.”
“What about moving feedgrounds away from the high-risk areas?” Price asked.
Sommers suggested perhaps one feedground could be moved and another could be used for test-and-slaughter.
“We need to prioritize the feedgrounds, do a risk assessment on each one,” he said. “If we ever really want to move the needle on this, rather than just having meetings every six months, we’re going to have to do some really hard work, get in there, and see if there’s any project we can use to reduce high risks…and then look at the options.”
“I think we need to keep our eye on different tools,” said University of Wyoming College of Agriculture and Natural Resources Dean Frank Galey. “Concentrating on risk assessment would probably be worthwhile. Otherwise, like Albert said, we’re just spinning our wheels.”
Jessica Crowder, representing Gov. Matt Mead, agreed with the need for the BCT to get more involved in reducing transmission risks.
“I want to say I appreciate this discussion about moving the needle,” she said, “and I think that will be appreciated by the Governor as well.”
RB51 developer discusses challenges, potential vaccine advances in the futureWritten by Natasha Wheeler
Washington, D.C. – In February 1996, USDA’s Animal and Plant Health Inspection Service (APHIS) licensed the Brucella abortus strain RB51 vaccine for use in cattle to reduce the prevalence of brucellosis, eventually replacing the use of the Brucella abortus strain 19 vaccine in the United States.
“Strain 19 is not a bad vaccine. It gave very good protection, but it produces antibodies that screw up the virology and, long-term, makes it very hard to eradicate the disease,” noted Gerhardt Schurig.
Shurig, an immunology professor in the Department of Biomedical Sciences and Pathobiology at Virginia-Maryland College of Veterinary Medicine, presented some of the challenges of developing the RB51 vaccine on Nov. 11 in Washington, D.C. at the Revisiting Brucellosis in the Greater Yellowstone Area meeting, hosted by the National Academy of Sciences.
“When I started the research, I wanted to find out what characteristics would make a better vaccine,” he explained.
There are two basic morphological forms of Brucella bacteria, a smooth form and a rough form. Strain 19 is composed of a smooth strain, which creates challenges related to antibody production and diagnostic testing for brucellosis.
“This point is important because we immediately began to think about using rough organisms, but how to select those rough organisms is where things became complicated,” he said.
The strain that is chosen must be attenuated, or weakened, so that it can be potentially administered to animals of any age.
“We don’t want to expose people to a disease if they are using a vaccine, and we certainly don’t want animals spreading the disease,” Schruig noted.
The Brucella strain also has to be stable and suitable for booster vaccines.
“It needs to be inexpensive and easy to administer as well,” he added.
In 1979, Schurig and his team began developing tools to select for desired Brucella strains, and in 1982, they presented positive findings for a potential vaccine at a conference in Baton Rouge, La.
“From 1980 to 1996, there were basically 16 years between having the strain and applying it. It takes a long time to have something approved,” he commented.
Now, scientists are trying to improve the efficacy of the vaccine by modifying how antigen qualities are expressed by the RB51 Brucella strain.
“There are many antigens that have been described as having protective qualities against Brucella, but are they the correct ones to use in a particular species? I think that is a very important question,” Schruig said.
In mice, scientists are seeing positive results, but cattle or bison may exhibit different responses to the same vaccine.
“We have to run those experiments, and that is where we get into trouble. It is now so expensive, and the regulatory things are so complicated, one kind of throws their arms up,” Schruig remarked.
Scientists are also interested in how RB51 impacts tuberculosis (TB). Along with modifying for increased protection against Brucella, Schruig and his team are hoping to create a strain that protects against TB as well.
“I think the concept is really valid,” he stated. “We believe we have the strain to protect against both, and now we have to test it.”
Brucellosis continues to show up in Wyoming, efforts maintain marketabilityWritten by Saige Albert
Riverton – Northwest Wyoming’s wildlife reservoir of brucellosis continues to create problems for cattle producers, and Wyoming State Veterinarian Jim Logan explained to producers at Fremont County Farm and Ranch Days that two new cases were seen in the state in late 2015.
Currently, Wyoming has two cattle herds that are quarantined due to brucellosis.
“Montana only has one bison herd under quarantine, and Idaho doesn’t have any currently,” Logan said. “In Wyoming, we were able to release a bison herd in Park County that had been under quarantine since 2010.”
Cases of brucellosis
With cases of brucellosis occurring in 1988, 2003, 2004, 2008, 2010 and 2011, Logan noted that 2015 also showed two new cases of brucellosis.
Shortly after a domestic bison herd was released from quarantine, an infected beef cow was found in a Park County herd. The herd was quarantined. Testing showed that only one cow in the herd was infected. The cow was removed, and the herd has successfully completed two negative, whole-herd tests.
Less than a week after the Park County herd was quarantined, a veterinarian at one of Wyoming’s livestock markets found a suspect positive cow.
“The suspect positive was not Brucella abortus,” Logan said. “Confirmatory testing showed that another bacterial infection tripped the test and skewed results.”
“Three days later, another suspect cow was found in Sublette County,” he continued. “There were five cows in a group of cull cows that were positive, and additional testing showed six more positive animals.”
One negative, whole-herd test has been conducted to this point, and Logan added that no additional cows were found from herds that had commingled or had fenceline contact with infected herds.
“We are going to see this disease crop up from time to time in cattle in the Greater Yellowstone Area,” Logan said, noting that the wildlife reservoir means that total eradication will be difficult.
“Brucellosis is a bacterial disease caused by Brucella abortus,” Logan explained. “It was recognized as a big problem in this country in the early 1900s, and it is still a problem in the Greater Yellowstone Area.”
Brucella bacteria are shed from infected animals at the time of birthing, and bacteria are transmitted orally or by inhalation.
“Any animal that licks or sniffs the fluids, placenta or an aborted fetus can become infected with Brucella,” he said, noting that, if a live calf is born to an infected animal, that calf can also carry the bacteria. “Brucellosis is a chronic disease. Once an animal is infected with Brucella, it is considered to be a lifelong carrier of the bacteria.”
Logan explained that many producers are aware that brucellosis causes abortions, but it is also possible to see live calves born to infected animals.
“Typically, if an infected calf reaches full-term, it is alive at birth, but it probably won’t survive more than a few days,” he said. “The bacteria affects the lungs in the baby, so it dies after showing signs of pneumonia. Ranchers treat with antibiotics, and the calf dies showing signs of pneumonia.”
Because the ranchers don’t suspect brucellosis, they often don’t call the vet, and brucellosis is able to persist in the herd.
As a result of the wildlife reservoir in the Greater Yellowstone Area, Logan said that temporal and spatial separation are key to reducing impacts from the disease.
“Temporal separation means to keep cattle separated from wildlife at the time that brucellosis could be transmitted,” he explained. “The key period we are worried about brucellosis transmission in February through June.”
In February, March and April, wildlife infected with brucellosis are likely to abort their calves. Those who deliver full-term calves are expected to deliver in May and June.
While focusing on the key timing, Logan also noted that keeping cattle as far away from the wildlife reservoir as possible spatially is also important.
“It is difficult to keep cattle away from wildlife sometimes,” he said, “especially when people depend on public lands for at least seasonal grazing.”
“The good thing is that summer, fall and early winter are not considered significant times for risk of exposure,” Logan noted.
Logan also noted that surveillance and management are vital to preventing the disease in cattle.
“Surveillance and management includes brucellosis testing,” he said. “I’m not suggesting that people everywhere in the state need to test for brucellosis, but within the boundaries of the Designated Surveillance Area (DSA), it is important.”
He continued, “At this point, we are not aware of a big risk factor in wildlife outside of the DSA, with the exception of Big Horn and Sheridan counties where we know there are infected elk.”
The Wyoming Livestock Board has designated Big Horn and Sheridan counties as an “Area of Brucellosis Concern,” and therefore surveillance testing there is important but is currently voluntary, Logan added.
Though Big Horn and Sheridan counties are not included in the boundaries of the DSA, seven hunter-killed elk were found to be positive for brucellosis during the 2012-14 hunting seasons. 2015’s hunting season did not find any new positives.
“We can also vaccinate for brucellosis,” Logan said. “Vaccination for brucellosis is mandatory in Wyoming for all heifers that are going to be kept for breeding purposes.”
Logan added that vaccination, however, is not 100 percent effective, though it is helpful in mitigating risk.
“Every herd, with the exception of the first one in 1988, has been 100 percent vaccinated for brucellosis,” he said. “Vaccination is another tool, and it reduces the chance of infection and abortion. It is not 100 percent. We have to combine vaccination with appropriate management to be effective.”
Researchers explore economic feasibility of brucellosis management techniquesWritten by Natasha Wheeler
Jackson – As an economist, Dannele Peck guides her brucellosis research by asking how economically acceptable the prevalence of the disease is in a given area. The goal, she maintains, is to determine which combination of management tools will achieve and maintain an optimal level as cheaply as possible.
“To do that, we have to figure out how costly the disease is, how costly the potential management tools are and how effective they are,” stated Peck, a University of Wyoming associate professor in the Department of Agriculture and Applied Economics, at the Sept. 16 meeting of a National Academy of Sciences committee reviewing brucellosis in the Greater Yellowstone Area (GYA).
Peck added that disease managers should also consider whether efforts are focused on elk or cattle and what factors may affect the spread of the disease.
“How costly is a case of brucellosis in a cattle herd?” she asked. “As a good economist, I will say that it depends.”
The size of the herd, the number of affected animals, the need for depopulation versus quarantine and the timeline for quarantine are all factors that can affect the cost of an outbreak.
Evaluating an outbreak
Using some averages and assumptions, Peck and her team estimated that a brucellosis outbreak would cost approximately $192 per head over a 12-month period.
“We have to understand how costly our management activities are,” she continued. “We don’t want to spend $15,000 to solve a $14,000 problem.”
To evaluate various management techniques, Peck and her team of graduate students determined the annualized costs of certain tools and compared them to the financial loss of a brucellosis outbreak.
Citing an example data set for a high-risk herd, Peck commented, “Something like an adult booster vaccination is cheap enough that it doesn’t have to very effective to be worthwhile. It only needs to eliminate five percent of the cost of an outbreak to pay for itself.”
In the same example, delayed grazing would have to be so effective that it eliminated an impossible 104 percent of the brucellosis cost.
Therefore, she concluded that a vaccination may be a potential solution, but delayed grazing would not be economically beneficial in that situation.
Value of tools
“When we have lower risk and there is less at stake, we are not going to be willing to invest as much in brucellosis management,” Peck continued.
Fencing haystacks, asking the Wyoming Game and Fish Department to haze elk and using adult booster vaccinations may still have some value in high-risk herds, while spaying heifers, using alternative feed schedules and hiring a rider to haze elk may become less economically viable when risk is reduced.
To compare finances for investing in particular tools, Peck remarked, “We could put that money away each year so by the time an outbreak hits, we have saved up the difference.”
Along with more typical management tools, Peck’s team also investigated fencing winter feedgrounds and running stocker operations.
Due to high labor costs, Peck stated, “Elk-proof fencing costs $95,000 to $100,000 per mile.”
Fencing also raises other concerns about neighboring operations and important wildlife migration routes.
“What if we got rid of reproductive cattle in the GYA?” questioned Peck.
Her team revealed that stockers are generally 50 percent less profitable than cow/calf/yearling operations.
“We would be asking producers to trade their brucellosis risk problem for what is probably a much larger financial risk problem. Producers are managing many other sources of risk,” she said.
The cost of a brucellosis outbreak and the costs of management tools vary by ranch, by year and by prices.
“It’s a very individualized situation. If we know the characteristics of a ranch, we can help narrow down the list of tools that might be economically worthwhile,” she remarked.
Researchers are learning more about how brucellosis is spread and what management tools may be effective, but Peck emphasizes the financial constraints of producers.
“We can’t forget our major economic questions,” she said.
State veterinarian reviews brucellosis casesWritten by Natasha Wheeler
Casper – Wyoming State Veterinarian Jim Logan spoke at the Wyoming Stock Growers Association (WSGA) livestock health and production committee meeting on Dec. 1 during the WSGA Winter Roundup in Casper, reporting on livestock health in Wyoming.
Brucellosis was addressed immediately, as one case has been confirmed in Park County recently. A positive test was confirmed in one cow in one herd of approximately 500 head. There was also one contact herd affected.
“The contact herd, by rule, is quarantined and required to test one time on all adult females. That has been done, and all of those cattle were negative, so the quarantine on the contact herd will likely, very soon, be released,” noted Logan.
The herd with the affected cow remains under quarantine and must undergo three consecutive, negative, total-herd tests at least 60 days apart. One of those tests must also be completed within 75 days of calving.
“We have to get a post-calving test because that is when antigens will be most likely to be in the blood stream of the cow for the test. If we are going to find the disease in an affected herd, it’s really critical that we do a post-calving test,” he explained.
Because of the seasonal timing that the brucellosis case was discovered, Logan is hopeful that the herd will meet all criteria to be released from quarantine before turnout next spring.
Logan also noted that finding only a single positive cow in a herd of nearly 500 head is a promising sign. Negative brucellosis tests within the herd and in the contact herd indicate that surveillance efforts are helping prevent the spread of the disease.
Another case of brucellosis has been detected in Sublette County, and the state vet lab released culture results testing positive for brucellosis on Dec. 10.
Five cows out of 62 head originally tested positive during a change of ownership test, required by Chapter Two Brucellosis Rules, and the herd was quarantined on Nov. 19, pending further results. As of Dec. 9, the herd has been designated as “brucellosis affected.”
Logan expressed his appreciation for cooperation from producers and veterinarians and added, “We expect to complete the initial stages of this response by the end of December with follow-up testing to occur in the following months.”
Five contact herds are currently under quarantine until further testing can take place to verify the absence of brucellosis in those animals.
“The Sublette County herd runs in common with about seven other producers, so we have seven contact herds. Luckily, if there is such a word in this context, three of those herds are not going to have to be tested because two of them run steers or spayed heifers. If we have neutered animals, we’re not worried about the spread of the disease,” Logan explained.
Some of the contact herds have already tested negative for brucellosis and additional animals are currently being evaluated.
“As far as we know right now, and logic would tell us this, it’s most likely that elk are the source of this brucellosis. The epidemiology done so far on all of these herds does not indicate there was any purchase of cattle coming in that would have brought the disease with them,” he commented.
Both cases were discovered within the boundaries of the designated surveillance area (DSA). Outside the DSA, seven seropositive elk have been detected over the last three years through hunter surveillance.
“When that first couple of elk were found in 2013 from the 2012 hunt season, it represented the first time that brucellosis had been found in anything, cattle or elk, outside of Wyoming’s DSA since Wyoming went brucellosis class free in 1985,” he mentioned.
This year, hunter-killed elk will continue to be monitored through mid-December, but so far, there have been no seropositive elk detected outside the DSA. Approximately 500 animals have been tested.
“We do have to be vigilant,” Logan stated. “If producers from Sheridan or Big Horn counties haven’t had risk assessments or don’t have herd plans, I would be happy to talk to them. A lot of people have stepped up, and we really appreciate that, but I think that there is more surveillance needed.”
That surveillance, he argued, is not just to satisfy other states but also to satisfy the cattle industry in Wyoming with assurance that there isn’t a barn door left open that a brucellosis affected cow can walk out of.