An LSU Agricultural Center researcher has assumed an important role -- as a disagreement between cattle producers and environmentalists is creating national interest in the bison herd in Yellowstone National Park.
Dr. Philip Elzer, an assistant professor in the LSU Ag Center's Department of Veterinary Science, is one of the few U.S. researchers specializing in brucellosis research with large animals. His expertise has come to the forefront as opposing sides square off over the question of brucellosis infection in the Yellowstone bison herd.
"Wyoming, Idaho and Montana are certified brucellosis free, but that could change if wild animals contaminate the cattle herds," Elzer says.
Brucellosis is a bacterial disease that for many years infected U.S. cattle and swine. Also known as contagious abortion or Bang's disease, the disease causes spontaneous abortions, infertility and lowered milk production. It can also spread to humans, where it's called undulant fever.
"In most instances the only sign of infection in cattle is reproductive failure due to abortions, thus the disease is usually considered a female disease," Elzer says. Otherwise-healthy animals contract the disease either from their mothers at birth or through contact with the aborted fetuses, afterbirth or the milk of infected females.
"Infected cattle and swine may remain carriers for life," he says. "The bacteria can hide in the lymph glands of infected animals for years."
Through persistent efforts of the Cooperative State-Federal Brucellosis Eradication program, brucellosis has been all but eradicated from U.S. cattle and swine herds. More than 40 states have been certified as brucellosis free, and others are nearly to that point.
Farmers and ranchers in brucellosis-free states are permitted sell animals across state lines and ship animals and animal products in international trade with few restrictions. Cattle and swine from states with the infection are subjected to regulations that require a negative brucellosis test prior to movement, Elzer explains. And such animals often are sold at reduced prices.
Ranchers have been concerned about brucellosis in Yellowstone since the beginning of the eradication program in the 1940s. But the Yellowstone bison were ignored as long as brucellosis was present in many of the nation's domestic herds.
"Now that Idaho, Wyoming and Montana are brucellosis free, ranchers are turning their attention to the Yellowstone bison," Elzer says.
Because free-ranging bison may share the same grazing lands as commercial cattle herds, cattlemen are concerned bison may transmit the disease to their cattle herds. In addition to the Yellowstone herd, only one private bison herd is known to be infected.
Elzer has been studying brucellosis for 14 years. The United States has only a few brucellosis research facilities where the disease can be studied in large domestic animals and in bison or other wild animals like elk or feral swine. Isolation facilities on the LSU Ag Center's Ben Hur farm and at Texas A&M University are used to study the disease in cattle, goats, sheep, swine, bison and elk.
Elzer has been working cooperatively with researchers at Texas A&M, which has special facilities designed to confine bison and elk, which pose a threat to domestic cattle herds. In several studies, researchers have used domestic animals as models for studying and treating wild animals.
The funding has come through numerous grants, mostly from a variety of federal sources.
"The bacteria that cause brucellosis can live outside the animal for several days under the right conditions," Elzer says. "This is a concern with cattle ranchers whose cattle can come in contact with aborted fetuses or placentas or with contaminated soil and vegetation left behind by infected animals. The bacteria have been shown to exist up to 21 days in abortion sites in Yellowstone Park."
Even though they're also known to be infected with brucellosis, elk aren't considered as significant a threat to cattle as bison.
"Elk are more private animals, especially when giving birth, so the spread of the disease among them is lower, and the likelihood of domestic animals coming into contact with aborted fetuses or placentas is extremely low," Elzer says.
For the past four years the Ag Center has hosted the national brucellosis conference, where scientists get together to discuss the goals and needs of the research and suggest protocols that need to be developed. Funding is granted based on these protocols and proposals.
"We want to find an efficacious vaccine to protect ruminant wildlife," Elzer says. The most common vaccine currently used is Brucella abortus RB51, a vaccine developed at Virginia Tech.
Elzer says his team and others have tested RB51 in bison and elk and have found that it is a safe vaccine, which doesn't appear to create any problems.
"The basic approach to brucellosis control has been to test cattle, send infected animals to slaughter and vaccinate the balance of the test-negative females," Elzer says. "Even though the disease is almost eliminated in cattle, it is still wise to vaccinate young replacement heifers.
"The ideal scenario with wild animals would be test the animals, remove those that test positive and vaccinate those that test negative," the researcher continues. "However, this form of control concerns many because of the fear that too many animals would test positive and be eliminated from the park."
The National Park Service approach to herd management is to leave the herd alone. They allow little or no human interaction. Therefore, they would not favor conventional vaccination of bison in Yellowstone, Elzer explains.
There is still a possibility that an oral brucellosis vaccine could be used on elk and bison. And oral vaccination would minimize human contact.
We've made a lot of progress," Elzer says. "We think we can protect wildlife and work better with existing park practices with an oral vaccine."
Researchers are testing oral vaccines that would permit the treatment of National Park animals without human contact. In addition to elk, Elzer is testing the vaccine on reindeer in Alaska.
"We know the oral vaccine works in elk," Elzer says. "Now we need to show it works in bison.
"We vaccinate to increase herd health and immunity," Elzer emphasizes. "We know we can't vaccinate the brucellosis out of existence, but we can reduce incidence to insignificant levels as long as vaccination continues."