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Stay vigilant to avoid brucellosis comeback

Not long ago it looked like brucellosis might go the way of the screwworm. But it quickly reared its ugly head again.

All 50 states plus Puerto Rico and the U.S. Virgin Islands were simultaneously designated brucellosis-free by the USDA after Texas was declared free of the disease on Feb. 1, 2008. This milestone event came after 74 years of cooperative efforts among federal, state and industry partners to get bovine brucellosis under control.

Then Montana reported two cases of bovine brucellosis within a 24-month period, with the second case marked on June 9, 2008. On June 30, 2008, bovine brucellosis was confirmed in two cows originating from a cattle herd in Sublette County, Wyo.

Many believe the sources of these infections are free-roaming elk and bison in Yellowstone and Grand Teton national parks.

Regardless, these recent reported cases of bovine brucellosis in Montana and Wyoming indicate that, although most of the U.S. is free of the disease, the threat still exists. That means beef and dairy producers need to keep their knowledge of the disease current and exercise good herd health management to keep their herds brucellosis-free.

Since there is no effective treatment for brucellosis, prevention is the only way to control it.

Symptoms of brucellosis include abortions, weak calves, delayed breeding, reduced milk production, mastitis, testicle inflammation and lameness.

Two of the most valuable control methods are to keep disease-free cattle from contact with infected cattle and to vaccinate heifers.

“A big risk to brucellosis-free herds is the addition of replacement animals,” says Tom Hairgrove, DVM, Texas AgriLife Extension Service. “Cattle should not be purchased if the seller cannot certify that they are free of brucellosis. Even with certification, breeding animals should be quarantined until the first healthy calf is born.

“Anytime abortions or breeding problems occur in a herd, I recommend testing for brucellosis as well as for other abortion-causing organisms,” he adds. “The earlier the disease is detected, the sooner management steps can be taken to rid the herd of the bacteria.”

Only one brucellosis vaccine, RB 5, is approved in the U.S. This vaccine can only be administered by an accredited veterinarian and is given to heifers at 4 to 12 months of age. Bull calves are not vaccinated because the vaccine can cause sterility in males.

“Due to the threat of bovine brucellosis infecting herds, many states require testing of adult cattle when ownership is changed,” notes Hairgrove. “If a cow or bull shows positive for brucellosis in initial testing, submit blood samples for a more extensive diagnosis.”

Occasionally cattle will catch swine brucellosis, usually from contact with wild pigs. It can cause bovine brucellosis tests to show positive. If that happens, producers must slaughter such animals, but they do not have to quarantine their ranch for bovine brucellosis.

Fears owns RJ Consultant Services and writes from Georgetown, Texas.

Brucellosis: adaptable and dangerous

Bovine brucellosis is caused by the bacteria Brucella abortus.

These bacteria enter cattle primarily through the mouth and occasionally through the eye. They exit the animal in all secretions and tissues associated with calving or abortion. Other common exit routes are through semen and milk.

Bovine brucellosis and five other species of Brucella can infect humans. The resulting disease is called undulant fever.

Bovine brucellosis is found worldwide but is under control in most developed countries.

Management practices that protect herds from contracting brucellosis

• Buy only certified brucellosis-free cattle.

• Quarantine new arrivals.

• Wear disposable plastic gloves when pregnancy testing or assisting in calving.

• Immediately remove aborted fetuses and placentas from pastures and dispose of them properly.

• Vaccinate heifers.

• Test cattle that abort, deliver weak calves or have trouble breeding.

• Maintain good fences to prevent contact of your cattle with strays.

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HEIFER CHECK: When buying herd replacements, ask the seller to certify that the heifers are brucellosis-free.

This article published in the April, 2010 edition of BEEF PRODUCERS.

All rights reserved. Copyright Farm Progress Cos. 2010.