The United States Department of Agriculture confirmed Tuesday that it found a case of bovine spongiform encephalopathy (BSE) in a dairy cow from central California.
The infected cow was found as part of a "targeted surveillance system," says John Clifford, the USDA's chief veterinary officer, who said at no time did it present a threat to humans.
This is the nation's fourth confirmed case since 2003 of the ailment known as mad cow disease, which can be fatal to humans who eat parts of the animal infected.
"The animal was never presented for slaughter for human consumption, so it at no time presented a risk to the food supply or human health. Additionally, milk does not transmit BSE," Clifford said. The cow was found at a "rendering plant," which takes sickly or sub-standard animal meat and recycles it into inedible products.
The animal tested positive for atypical BSE, a very rare form of the disease not generally associated with an animal consuming infected feed.
The USDA in collaborating with international animal labs and U.S. public health officials to determine the origins of the case.
It does not expect the finding to affect U.S. trade in beef.
Worldwide cases of BSE peaked in 1992 with 37,311 confirmed cases. In 2011, there were 29 cases. This is attributable primarily to the use of feed bans, according to the USDA.