Mad Cow Disease Discovered in California, For the First Time in Six Years

For the fourth time ever in the United States, a cow has tested positive for mad cow disease—this time in California, according to the Associated Press.

Officials at the U.S. Department of Agriculture told the AP the infected dairy cow, discovered at a Central California rendering plant, was not bound for the food supply and is not indicative of a larger problem.

"There really is no cause for alarm here with regard to this animal," John Clifford, chief veterinary officer for the department, told the AP.

Mad cow disease, or bovine spongiform encephalopathy, was last seen in the U.S. in 2006 and is caused by misfolded proteins in a cow's brain. A fatal human version, Creutzfeldt-Jakob disease, can spread to people who consume diseased meat.

The California cow did not acquire the disease from tainted feed, the USDA says, and veterinary experts told the AP a random brain mutation was the likely culprit.

The United States tests about 40,000 cows per year for mad cow disease, a lower percentage of the herd than in other countries. Japan, for example, tests every cow destined for human consumption and has found more than 30 cases of the disease since 2001.

Reuters reports the Chicago live cattle futures market fell as news of the infected cow spread Tuesday, but rebounded after federal officials said the food supply was safe.

Dairy farmers, does this new report of mad cow disease concern you? Consumers: Will it make you think twice about drinking milk or eating beef? Tell us in the comments.