Brucellosis eradication is now focused on Yellowstone National Park.

The battle is nearly won. There is now no known brucellosis infection in commercial cattle or bison in the U.S.

“We reached an apparent zero infection in late December when Florida lifted a quarantine on a previously infected herd that had been cleaned up,” says Bob Hillman, Idaho state veterinarian and president of the U.S. Animal Health Association (USAHA). In addition, the last known brucellosis-infected herd in Texas has been depopulated, according to Hillman.

No newly infected herds have been found in the U.S. since last July when infection was disclosed in a cattle herd in Navarro County, TX. But, Hillman says, while this is all good news, the cattle and bison industries can't relax surveillance efforts. “This is an insidious disease whose signs are not always easily seen,” he says.

The only remaining focus of brucellosis in the U.S. is in the Greater Yellowstone Area. This includes Yellowstone National Park areas located within Idaho, Montana and Wyoming, where free-ranging bison and elk are infected.

“These animals pose a disease threat to cattle in surrounding brucellosis-free states and serve as the only known source for reintroduction of the disease into domestic cattle and bison herds,” explains Hillman.

State and federal officials are working to develop and implement plans to control and eventually eliminate brucellosis from bison and elk in the Greater Yellowstone Area, he says.

Currently, 46 states, Puerto Rico and the U.S. Virgin Islands are classified as brucellosis-free. This means they have had no infected cattle or domestic bison herds for at least one year and have active surveillance programs in place.

Four states — Florida, Missouri, Oklahoma and Texas — are in the final stage of eradication. With no known infection at this time, these states are now in the final one-year countdown phase.

USDA's Animal and Plant Health Inspection Service carries out the brucellosis eradication program in cooperation with the cattle industry and animal health agencies in the various states. Efforts to combat brucellosis began as part of a cattle reduction program in July 1934 because of extreme drought conditions.

The program lapsed during World War II but was accelerated in 1954 as an eradication effort with additional funds. At that time, an estimated 124,000 cattle herds were infected with the disease.

A major program boost came in 1978 when a special commission's two-year study concluded that “control leading to eradication is biologically feasible.”

By August 1990, the number of quarantined herds had dropped below 1,000. Five years later, that figure was fewer than 100. In 1997, the Brucellosis Emergency Action Plan, which provided additional funds and procedures, was implemented.

It's been estimated that if brucellosis were allowed to spread, beef and dairy production costs would increase by an estimated $80 million within 10 years.

USAHA is composed of state and federal veterinarians, laboratory diagnosticians, researchers, academics and livestock producers. It's been instrumental in developing and recommending implementation of standards for the cooperative state-federal brucellosis eradication program.

Brucellosis is a contagious disease caused by the bacteria Brucella abortus. It causes abortions in cattle and can cause undulant fever in humans who consume milk from brucellosis-infected cows.