An April-to-August investigation has closed the book on the fourth case of Mad Cow Disease, or bovine spongiform encephalopathy (BSE), in the United States. The California Holstein discovered last April was an isolated incident, poising no threat what-so-ever to the U.S. cattle herd or food safety.  The three month investigation ended in the same place it began, with USDA’s Chief  Veterinary Officer, Dr. John Clifford,  giving the all clear signal. “The results of this thorough investigation confirmed that at no time was the U.S. food supply  or human health at risk, and that the United States longstanding system of interlocking safeguards against BSE continues to be effective,” said Clifford. The ten-year old dairy cow was only the fourth ever discovered in the U.S. with the prion disease known as BSE. The diseased cow was found through brain tissue sampling last April 24 at a Baker Commodities rendering transfer station in Hanford, CA as part of USDA testing. The dairy cow was unable to stand and was put down on April 18 before the rendering company picked up the carcass. BSE cannot be transmitted by milk. USDA tracked the Holstein to the ranch where she was born, raised and bred to activate her mammary glands and to the Tulare County, CA dairy where to spent her life. They identified 282 “cohorts” where the Holstein was born and traced 210 that might have made it into the food system. One of its offspring was slaughtered, but was not infected.   There is no live-animal test for BSE. Unlike the first Mad Cow found in the U.S., near Mabton, WA on Dec. 23, 2003, subsequent discoveries in Texas in 2005, Alabama in 2006, and now California in 2012, have not had as much impact on U.S. beef export. The fourth Mad Cow has caused some hiccups in Taiwan’s purchases of U.S. beef, but others have not been that much effected. The first Mad Cow discovering cost U.S. beef billions in a major disruption of its exports that took years to recover. This time, the cow involved was never going to be slaughtered for sale for human consumption, and it may have been the subject of “atypical” BSE that just happens occasionally without requiring the animal to eat rendered protein supplements derived from slaughtered cattle. British beef experienced a major outbreak in the 1990s when cattle were fed brain and spinal cord materials containing the prion disease. Rendered cattle are no longer feed to cattle, but there is concern about such use in chicken feed and it  could get back to cattle. The Holstein was one 71 cattle collected by the rendering company in that collection. All the carcasses were quarantined before seated in plastic vaults and disposed in a landfall. Worldwide, there were 29 cases of BSE discovered in 2011 — a 99 percent reduction since 1992 when there were 37,311 cases. The U.S. Food and Drug Administration (FDA) investigated dozens of feeds since the April discovery without finding any not in compliance with current regulations.