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Texas Agriculture Archive

December 5, 2003

Don't get lax with
brucellosis vaccinations

The recent positive test for brucellosis on a Henderson County cattle herd underscored the need for continued testing and vaccination by cattle producers, said Dr. Jason Cleere, beef cattle specialist with Texas Cooperative Extension.

In early October, the Henderson County detection broke a 13-month stretch during which no newly infected herds were detected in Texas. After 12 months of no detection, a state can apply for "brucellosis free" status, and Texas animal health officials were on the verge of doing so when the infected herd was discovered.

"The 13-month period of no new brucellosis detection proves the system is working," Cleere said.

Currently, Texas and Missouri are the only states in the nation not free of brucellosis. Undetected, the disease can cause cows to abort, deliver weak calves and produce less milk.

Because cooked meat of brucellosis-infected cattle is safe for human consumption, cows and bulls from the infected herd will usually be sent to slaughter. The herd owner is reimbursed by the slaughter facility and receives an indemnity from the U.S. Department of Agriculture and Texas Animal Health Commission to help offset the loss of the adult cattle and nursing calves. Weaned steers and spayed heifers may be kept, because these animals cannot spread brucellosis, which is transmitted primarily by infected cows during abortion or calving.

Despite the reimbursement and indemnity, a brucellosis infection can be economically devastating to a producer. Though market price is paid, it doesn't necessarily account for the years a producer invested building his herd.

Texas animal health regulations require that all heifers and cows be tested before they are sold. This testing is usually performed at the sale barn. A single animal testing positive for brucellosis can result in the seller's entire herd being quarantined.

It's easy to demonstrate that the law is working to eradicate brucellosis. Not that many years ago, Texas had thousands of infected herds. These herds were often quarantined for up to a year or longer, while the Texas Animal Health Commission periodically tested the cattle and removed all infected animals for slaughter, Cleere said.

While the herd was in quarantine, individual animals could be sold only to slaughter which could be a hardship for the rancher. There also was the chance that infection could be spread to nearby herds during the quarantine.

Now, it is more common to depopulate infected herds as soon as a diseased animal is detected, with the aim of avoiding spread of the disease to nearby operations and lessening the hardship for the producer. With an immediate depopulation of the herd, the producer is back in business within weeks.

The best defense remains vaccination of heifers four to 12 months of age, Cleere emphasized.

In most situations, vaccination is now voluntary. Also, Cleere noted, there is no risk of the new vaccine, RB-51, creating false positives on tests. An accredited veterinarian must administer the vaccine. The cost of vaccination should be about $6 per head, but this fee could be more or less depending upon the number of heifers treated and the veterinarian involved, Cleere said. The heifer must only be vaccinated once to be protected for life.

With an effective vaccine and monitoring of all sales, why are infected herds still appearing?

Two possible reasons are usually suggested, Cleere said. An infected animal may remain in a herd for years, and the disease discovered only when it goes to the sale barn. The other reason may involve a producer who for years has maintained a closed herd, keeping all heifers or cows and just selling steers and bulls. When the entire herd is sold, which sometimes occurs after the death of the producer, the diseased cows are discovered through the mandatory testing rule at the sale barn.

"We need to keep monitoring the disease and vaccinating," he said.