America’s fourth case of bovine spongiform encephalopathy (BSE) was confirmed today in a press briefing by the USDA. John Clifford, USDA’s chief veterinarian, said a dairy cow expressing an "atypical" case of BSE was found at a rendering facility in central California and the carcass is being held under State authority and will be destroyed.

Clifford said the animal was never presented for slaughter for human consumption and was never a risk to enter the food supply for human consumption. Additionally, it was noted, milk does not transmit BSE. This is the fourth case of BSE found in the United States since December 2003.

Cattle futures markets locked limit down shortly before trading ended Tuesday as rumors of the BSE case circulated through the trading floor.

Clifford emphasized the safeguards in place to protect America’s food supply from BSE. "The United States has had longstanding interlocking safeguards to protect human and animal health against BSE. For public health, these measures include the USDA ban on specified risk materials, or SRMs, from the food supply. SRMs are parts of the animal that are most likely to contain the BSE agent if it is present in an animal. USDA also bans all nonambulatory (sometimes called "downer") cattle from entering the human food chain. For animal health, the Food and Drug Administration (FDA) ban on ruminant material in cattle feed prevents the spread of the disease in the cattle herd.

Clifford said the U.S. will share laboratory results with international animal health reference laboratories in Canada and England, which have official World Animal Health (OIE) reference labs. “These labs have extensive experience diagnosing atypical BSE and will review our confirmation of this form of the disease. In addition, we will be conducting a comprehensive epidemiological investigation in conjunction with California animal and public health officials and the FDA.”

Clifford also emphasized this new BSE case “in no way affects the United States' BSE status as determined by the OIE. The United States has in place all of the elements of a system that OIE has determined ensures that beef and beef products are safe for human consumption: a mammalian feed ban, removal of specified risk materials, and vigorous surveillance. Consequently, this detection should not affect U.S. trade.