Preliminary test results indicate that a dairy in west Texas is infected with cattle tuberculosis (TB). Cattle TB is caused by the Mycobacterium bovis bacteria and can cause internal lesions in animals. Milk from commercial dairies is pasteurized, killing bacteria with heat, so there is not public health concern from this herd detection.

“Animals from the 2,600-head dairy were being prepared for sale and some reacted to TB skin tests. The follow-up blood tests on these animals also were positive,” said Dr. Bob Hillman, Texas state veterinarian and executive director of the Texas Animal Health Commission, the state’s livestock and poultry health regulatory agency. “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. The lesions are microscopically compatible with TB, and Polymerase Chain Reaction (PCR) tests on the tissues have detected the DNA, or the basic genetic material of the disease. The final confirmation is based on a culture, which may take several weeks. It involves identifying bacterial growth from the tissue samples as Mycobacterium bovis.”

“We will be determining the dispensation of the herd in the next few days,” said Dr. Hillman. “An epidemiological investigation has been launched to determine the source or possible spread of the disease.”

Texas regained cattle TB-free status in fall 2006, after losing the coveted status in spring 2002. Dr. Hillman noted that one TB-infected herd will not affect the state’s status, but two infected herds within a 48-month period will result in a loss of TB-free status. Texas’ most recent TB-infected herd was a dairy, detected in 2004 and depopulated. California lost its TB-free status in September 2008, and Minnesota, Michigan and New Mexico are split states, meaning areas within these states have different TB statuses. All other states currently are TB-free.