The Texas Animal Health Commission (TAHC) confirmed last week that a cow from a West Texas dairy tested positive for Mycobacterium bovis, or cattle tuberculosis (TB). The herd was initially quarantined in April after some of the herd reacted to a TB skin test before a sale.

Dr. Bob Hillman, a Texas state veterinarian and executive director of the Texas Animal Health Commission, said in an earlier press release said the herd had positive TB results after several rounds of testing.

“Animals from the 2,600-head dairy were being prepared for sale and some reacted to TB skin tests,” Hillman said. “Samples were collected from two of the cattle slaughtered for examination, and the tissues were submitted to the National Veterinary Services Laboratory in Ames, Iowa for additional testing.”

Hillman said the lesions are microscopically compatible with TB and the final confirmation would be based on a culture.

“The infected herd remains quarantined while the final disposition of the heard is determined - either slaughtering the herd, or repeatedly testing and removing infected animals until the herd is free of cattle TB,” Hillman said. “Dairy, calf-raising and dairy animal replacement operations with epidemiological links to the infected herd are being tested to determine both the origin and potential spread of the disease.”

Although TAHC representatives would not confirm the name or location of the infected dairy, other reports said the cows were from Tapia Farms, on their way to Erath County Dairy Sales (ECDS) for auction.

Jason Beyer of ECDS said the Tapia Dairy cows were tested at the dairy before they made it to the sale barn.

“The one that was confirmed never left the dairy,” Beyer said.

Beyer said the test is a routine procedure for dairy cattle and must be performed before the livestock can be moved out of state.

He said that if a TB-positive cow had made it to the barn, they would have sent the offender back to the dairy and then cleaned and sanitized all pens and equipment.

According to information provided by TAHC, the quarantined herd must pass five annual post-quarantine tests to show the disease has been eliminated, followed by two more tests at three-year intervals. 

The disease is commonly eliminated from a herd through depopulation.

“Cattle TB is a serious, transmissible disease that can spread among herds,” Hillman said. “In the early 1900s, when the national cattle TB eradication program was initiated, more than five percent of the country’s herds were infected with the disease. At that time, cattle TB posed a significant human health threat, because consumers could become infected when they drank raw, unpasteurized milk that had not been through heat-treatment to kill bacteria.”

Although the cows from the infected herd can only be sold for slaughter, TAHC said the milk produced from the herd is safe for consumption once it has been pasteurized. 

Texas initially gained TB-free status in November 2000 but lost that status after an infection was detected in a beef herd in June 2002.

Texas regained cattle TB-free status in fall 2006, after losing the coveted status in spring 2002. Hillman noted that one TB-infected herd would not affect the state’s status but if another herd tests positive within a 48-month period, Texas would once again loss its status. Prior to this incident, the last confirmed case of cattle TB was in 2004.

California lost its TB-free status in September 2008, and Minnesota, Michigan and New Mexico are split states according to TAHC, meaning areas within these states have different TB statuses. All other states are TB-free.