The first U.S. case of mad cow disease in six years was discovered in a 10-year, 7-month old dairy animal in Tulare County, California, that was euthanized after it became lame, the U.S. Department of Agriculture said.
The animal’s carcass will be destroyed, the USDA said in an e-mailed statement late yesterday. The cow was targeted for testing at a rendering facility as part of the department’s surveillance program for the brain-wasting disease, known as bovine spongiform encephalopathy, or BSE, the USDA said.
“This animal was never presented for slaughter for human consumption, so at no time presented a risk to the food supply, or to human health in the United States,” the USDA said in the statement. BSE isn’t spread through milk. The department on April 24 announced that the infected animal had been found, while providing few details.
This is the fourth animal found with BSE in the U.S. herd, and the first since March 2006. After the initial case in 2003, dozens of countries banned U.S. beef, and exports fell 82 percent to 460.3 million pounds the following year. This time, Canada, Mexico, Japan and South Korea -- the four biggest buyers -- and the European Union have said they won’t halt purchases. Indonesia said yesterday it was restricting imports.
Scientists say the disease is spread through feed that contains brain or spinal-cord tissue from infected animals. People can get a form of the fatal illness from eating products containing such tissues. Since 1997, feed made from mammals has been banned from cattle rations. Slaughterhouses are also required to remove high-risk materials to ensure they don’t enter the human food supply.
The California animal was diagnosed with a rare form of the disease called atypical BSE, which develops spontaneously and is not contracted through infected feed. This form of BSE is also consistent with an animal born after the feed ban, officials say.
Once “at-risk” cattle are identified, they are killed and tested, the USDA said.
Investigations typically include tests of animals that were in the same herd as the diseased cow, as well as feed the animal may have consumed. Even when an animal tests positive for a form of BSE not connected to feed, as in this case, the investigative procedures are the same, according to John Clifford, the USDA’s chief veterinarian. Any offspring of the infected animal are also checked.
Tulare is the nation’s biggest milk-producing county, with 502,395 cows on 311 dairies in 2010, according to the most recent available data from the California Department of Food and Agriculture. The jurisdiction accounts for more than a quarter of all the milk produced in California, the nation’s leading dairy state.