The Department of Agriculture could cancel Texas' "free" status for cattle tuberculosis eradication because the disease has been diagnosed in two of the state's estimated 153,000 cattle herds since summer 2001. Texas had gained TB-free status in November 2000, with the exception of portions of El Paso and Hudspeth counties, which had been "zoned out" because of new cases of the bacterial infection.
"According to the USDA's Code of Federal Regulations for tuberculosis, any state will lose its 'free' status when two infected herds are detected within a 48-month period," said Dr. Linda Logan, Texas state veterinarian and executive director of the Texas Animal Health Commission, the state's livestock health regulatory agency.
"Our first infected beef cattle herd was found and depopulated in Fayette County this past summer. We have just completed depopulating an infected beef and dairy operation headquartered in Pecos County."
TAHC and USDA staff tested more than 60 herds and traced five years of cattle movement into and out of the Fayette County herd in their effort to pinpoint the origin of the TB infection. At press time, epidemiologic tracing and testing was still under way for the Pecos County herd.
"We anticipate that the USDA rule to downgrade Texas' TB status from 'free' to modified accredited advanced status could be published sometime in April ," said Dr. Richard Ferris, area veterinarian-in-charge in Texas for the USDA's Animal and Plant Health Inspection Service, Veterinary Services, at press time in late March. He noted that the specific regulation changes would affect all of Texas, except El Paso and Hudspeth counties, which will remain separate, because of high-risk herds awaiting federal depopulation.
"The USDA is deferring until January 2003 its requirement for Texas feeder animals to be officially identified before they leave the state," Dr. Logan said.
If no additional infection is detected after two years, Texas could apply with the USDA for reinstatement of TB-free status.
"We know Texas has been at particular risk for TB, because Texas livestock brokers import nearly a million Mexican feeder cattle each year," Dr. Logan said. "TB-infected cattle continue to be a problem in many Mexican states. Many of these Mexican feeder animals are placed on pastures across the state until they're heavy enough for the feed yard. Potential exposure between these cattle and domestic cow-calf operations spreads our risk across the state." She noted that, in fiscal year 2001, 64 TB-positive cases were detected in U.S. slaughter plants. Of the 50 cases investigations that have been completed, 48 involved Mexican-origin cattle.
Since October 2001, Mexican-origin cattle have been involved in seven of nine TB cases in feedlot animals.
"We've worked closely with Mexico on TB eradication since l988, when the USDA began offering training and technical support," she said. "Since l994, Mexican cattle have been imported under a 'consensus agreement.' New federal regulations will be implemented for Mexican imports this April, which will provide more disease protection not only for Texas, but also for the other states that receive Mexican-origin feeder animals."