Brucellosis is a bacterial disease that has become an economically significant disease in the United States and particularly to our area in the Greater Yellowstone Area (GYA). The Brucellosis bacterium results in an abortion in most infected cattle at approximately 5-7 month of gestation. Brucellosis is spread by direct contact among cows, with the placenta and aborted fetus’ of infected cows being particularly high in bacterial concentration. When susceptible cows sniff an aborted fetus, there is a high likelihood that the susceptible cow will become infected.
The USDA began a nationwide eradication program in the 1950’s when a vaccine against the disease became available. We call the vaccine used to prevent Brucellosis a “Bangs” vaccine after the inventor of the original vaccine.
Throughout the country, Brucellosis has been successfully eradicated except around the GYA. The Bison and Elk in Yellowstone serve as a reservoir for infected animals. Though efforts have been made to try to eliminate the bacteria from the wild population, these efforts have not yet been successful, and the fact that cattle in our area often share grazing areas brings our cattle into direct risk of infection from these wild populations.
Heifers are vaccinated between 4 and 12 months of age, but even good vaccines are unable to provide complete immunity to every individual. Because of this, the state’s that boarder the GYA have implemented a surveillance program where all cows that are moved out of an area they have defined surrounding Yellowstone, called the designated surveillance area (DSA), get a blood test to check for Brucellosis before they can leave that area. While this no doubt seems like a huge hassle to cattle producers, the surveillance program has been put into place to make sure that beef from this area is marketable. That is to say, the area around Yellowstone is typically most conducive to cow/calf operations, which means that our calves and replacement stock needs to be sold outside of our area. In order for states that have currently eradicated Brucellosis to be willing to accept our beef into their state, they need to know that the risk of Brucellosis being spread to their state is minimal. Testing each cow when they leave the DSA is how other states ensure that our beef is not going to contaminate their state, which keeps our beef marketable.
As predators in our area continue to change the migration pattern of the elk and bison herds, the surveillance area and surveillance areas will likely have to continue to change to keep our beef in high demand.