Brucellosis in cattle is not a huge concern, though the disease can be transmitted among different animal species.
Brucellosis, or Bang’s disease, is a disease of cattle caused by Brucella abortus. It’s a public health concern because it is zoonotic—it can be shared by animals, including sheep, cattle and water buffalo, goats, pigs, deer and elk, moose, equines, camelids, marine animals, canines, and humans.
In cows, brucellosis causes abortion; in humans it causes undulant fever, a condition that comes and goes like malaria. The first sign of infection in cows is abortion or birth of weak calves, typically between the fifth and seventh month. Other signs include lower fertility and poor conception rates (the most prominent signs in all animals), retained afterbirth, and enlarged, arthritic joints. Even when calves are born healthy, the infected cow still harbors and sheds the disease. Once the cow is infected, there is no way to cure it. Animals become infected through breeding or eating contaminated feed. The disease is shed in the infected animal’s milk, aborted fetus and afterbirth.
In humans, the infection can cause extreme joint pain, fever, depression and chronic fatigue. Humans can contract the disease by handling a cow’s aborted fetus or afterbirth or by eating or drinking contaminated milk products such as unpasteurized milk or cheese from an infected cow. Humans can be treated for the infection effectively with antibiotics; however, they may still experience symptoms of the disease.
In the 19th century, French chemist and biologist Louis Pasteur recognized that heating milk to a minimum temperature of 161 degrees F for at least 15 seconds kills both Brucella and the agent that causes tuberculosis; hence, we began pasteurizing milk. In the 1950s, there was a big push to eradicate tuberculosis and brucellosis in livestock in the U.S. Today, brucellosis is well controlled, but bacteria have a way of reinventing themselves.
The biggest problem today remains with the brucellosis-carrying bison and elk in the greater Yellowstone area, including the national park. They are not restricted to one area, so they migrate out of the park and have the potential to infect domestic cattle, particularly on ranches in southern Montana and northwestern Wyoming.
Hobby farmers with cattle should still be concerned, and there is a simple vaccination called the brucellosis or Bang’s vaccine. In many states, such as California, state law requires a one-time vaccination to every calf before it is 11 months old. After the animal is vaccinated, it’s given a mandatory tattoo and an optional ear tag (called the Bang’s tag) to show it has been vaccinated.
Brucella melitensis, one of three strains of Brucella found only in goats and transmissible to humans, causes abortion in goats and Malta fever, a condition worse than undulant fever, in humans. It’s always a good idea to have your veterinarian take a blood sample to check for Brucella melitensis before introducing a new animal to the herd, because the most common method of spreading the disease is through contact with new, untested livestock. If the newbies were born on your property and your farm’s been disease-free, it’s not that big of a deal. Unfortunately, no vaccine in the United States or Canada protects against Brucella melitensis.
—John Maas, DVM, MS, DACVIM, veterinarian and beef cattle specialist for the University of California, Davis Cooperative Extension
This article originally appeared in the September/October 2011 issue of Hobby Farms.
About the Authors: Sharon Biggs Waller is an award-winning writer and author of Advanced English Riding (BowTie Press, 2007). She lives on a 10-acre hobby farm in northwest Indiana with her husband, Mark, 75 chickens, two Lamancha goats, two horses, and an assortment of cats and dogs. Dr. Lyle G. McNeal is a livestock specialist in the Department of Animal, Dairy and Veterinary Sciences at Utah State University.