Brucellosis: a community disease

by Cat Urbigkit

It was a big crowd in attendance at Monday night's brucellosis meeting in Pinedale, with KPIN station owner Bob Rule counting more than 300 people, including at least a dozen local law-enforcement officers there to keep the peace.

Governor Dave Freudenthal, Senator Craig Thomas, Representative Monte Olsen and Wyoming Agriculture Director John Etchepare joined a panel of five federal and state veterinarians in answering questions for more than four hours, with the governor committing to staying until the last question was answered. That did happen, with the meeting lasting until nearly 11:30 p.m.

So far there have been 31 head of brucellosis-infected cattle discovered on one ranch near Boulder. Testing of neighboring herds is ongoing, according to Wyoming State Veterinarian Dr. Jim Logan. Logan said that as of Monday night, test results on another 1,600 head of cattle revealed those herds to be clean.

Federal brucellosis specialist Dr. Valerie Reagan of APHIS summarized disease information in livestock, pointing out that there is a direct relationship between the dose exposed to and the likelihood of infection; the incubation period can be from two weeks in some animals to as long as two years in heifers; and infected cows often show no clinical signs of infection.

Heifers and pregnant animals are the most susceptible to the disease, while older animals tend to be more resistant to brucellosis, Reagan said.

The route of infection is primarily by exposure to an infective abortion or infective calving. Reagan said the abortion of one calf could actually put out about 100 million doses of the disease on the ground.

"It only takes one abortion to cause havoc in a herd," Reagan said.

The infection in adult animals is considered to be permanent, with succeeding pregnancies frequently infective as well.

"Brucellosis is a community disease," Reagan said, and has to be treated as such. With work to eradicate the disease from the nation's livestock herds undertaken since 1934, all new brucellosis case management and surveillance actions are conducted as emergency actions.

The effectiveness of the new vaccine, RB51, in contrast to the old Strain 19 vaccine, was the subject of much concern from the ranchers present, but the animal health officials present pointed out that both of the vaccines had apparently been overwhelmed by disease exposure in this case.

Dr. Brett Combes of the USDA Animal and Plant Health Inspection Service said laboratory workers conducting the confirmatory tests were "amazed at how hot these titers were."

Besides the 31 reactor cattle in the Boulder herd, there are another 20-plus animals that are considered "suspects" in the herd, Combes said.

Combes pointed out that of the 31 reactors in the Jensen herd, 22 had been vaccinated with RB51, while seven more had been vaccinated with Strain 19. The infection rate of each of the vaccinates was similar: 10 percent of the Strain 19 vaccinates in the herd tested positive for brucellosis, and 10 percent of the RB51 vaccinates tested positive as well.

Reagan said, "We obviously had a very high infective dose, probably within the last year or two."

APHIS Yellowstone Brucellosis Coordinator Arnold Gertonson said, "The efficacy of the two vaccines are identical ... RB51 is just as effective as Strain 19."

Reagan agreed, "These breaks have occurred with both vaccines." She noted that with infected wildlife, herds are continually exposed: "everyday there is a new risk."

"The dose of infection is instrumental in over-riding the vaccine," Logan added.

Logan noted that this recent brucellosis outbreak in a single cattle herd in the county will probably precipitate another federal brucellosis review, as was conducted twice in the late 1990s by a federal review team of brucellosis experts.

Jerry Jensen was first to raise the issue of infected elk transmitting the disease to livestock. He noted that his family may be looking at eliminating their entire cattle herd, but the nearby infected elk herd remains unthreatened by similar action.

Logan said he certainly understands the frustration, but added, "We at this table do not have jurisdiction over wildlife."

Concentrating elk on elk feedgrounds allows the disease to proliferate, but as rancher Dan Budd said, closing the feedgrounds now would only spread the disease to more livestock herds, as the elk would disperse off the feedgrounds.

"This is a two-edged sword," Budd said.

Logan said it's too soon to be able to trace where exactly the infection came from, but when questioned about transmission from elk, responded, "Certainly I have my suspicions, as you do."

After listening to the discussion for several hours, Senator Thomas questioned Reagan, "What do you propose as a solution to the problem we have?"

Reagan, pointing out that the national eradication program has eliminated the disease in other areas, said eradicating it here is "doable." She suggested the right people be brought to the table to brainstorm on solutions to problems, rather than shooting at each other.

Reagan said elk can't be treated like cattle, and each elk herd should have a disease eradication plan developed to address its specific situation. She even suggested simple things like placing elk feed in troughs, to keep the feed off the ground and reduce disease transmission. If the troughs need to be portable, they can be mounted on skis, she said.

Thomas pointed out that the Greater Yellowstone Interagency Brucellosis Committee has worked on the wildlife disease issue for some time. He told Reagan, "But you've been at the table for five years."

Reagan said, "No we haven't been to the table, we've been in court quite a bit."

Joel Bousman asked Freudenthal to establish a task force to address this ongoing brucellosis concern at the state level. Freudenthal agreed to pursue the matter, adding that he had already briefly discussed it with Olsen and Thomas. He said there are questions about how the group would be configured and funded, but added, "We're clearly going to have to act on it."

Freudenthal said state efforts should be on a parallel track with the interagency effort. He said the state could go it alone, "but it ain't going to be easy."

Freudenthal said, "I am committed to figuring it out."

Reagan said adult vaccination of cattle herds is certainly a possibility in this area, but added that the brucellosis risk has to be weighed, addressed and managed on a herd-by-herd basis. She said in some cases, her agency will pay for brucellosis testing and vaccination, "as part of a controlled eradication program."

When a newly infected livestock herd is discovered, Reagan said, "whenever possible" those herds are depopulated, meaning sent to slaughter. She emphasized that this action is not mandated, but is a decision made by the herd owner. The herd owner's other option is long-term quarantine and retesting.

Reagan emphasized that depopulation isn't forced, but admitted the alternatives aren't good either.

Logan noted that if the Jensens, who own the infected herd, do not agree to depopulating their herd, Wyoming will lose its brucellosis-free status, which provides for free movement to market.

"If we lost our brucellosis-free status that rule would be statewide," Logan said.