Texas officials lifted a quarantine Monday on the ranch that produced the first native case of mad cow disease, saying tests on 67 animals from the herd came back negative for the brain-wasting disease.
Federal officials now plan to focus on checking market documents to trace animals of the same age that may have left the ranch, said Larry Cooper, spokesman for the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service.
“We’re pretty confident that we can track a good number of them,” Cooper said.
The quarantine had gone into effect June 10 after U.S. Agriculture Secretary Mike Johanns announced he was sending samples to England for further testing. Lifting it allows animals to come and go from the ranch.
The location of the ranch has not been disclosed.
Mad cow disease, or bovine spongiform encephalopathy, eats holes in the brains of cattle and is incurable. The disease is a public health concern because humans can develop a brain-wasting illness, variant Creutzfeldt-Jakob disease, from consuming contaminated beef products.
The infected Texas animal had a history of “erratic behavior” and had fallen a couple of times but did not enter the human food supply, Cooper said. It was born before a 1997 ban on feeding cattle protein or bone meal made from other cattle or other ruminants.
Initial screening on the Texas cow indicated the presence of the disease, but results from more sophisticated tests were negative, and the department declared the animal free of mad cow. The USDA’s internal watchdog ordered more tests last month that came back positive, and a laboratory in England confirmed the results June 24.
The animals killed at the ranch for testing were all born within about a year of the diseased 12-year-old Brahma cross beef cow.
Since June 2004, six months after a Canadian-born Holstein shipped to Washington state became the first U.S. case of the disease, the USDA has tested more than 400,000 cows. In 2003, it tested 20,543.