Preliminary Investigation Suggests BSE-Infected Cow in Washington State Was Likely Imported from Canada
On December 23, 2003, the U.S. Department of Agriculture (USDA) announced a presumptive diagnosis of bovine spongiform encephalopathy (BSE, or "mad cow" disease) in an adult Holstein cow from Washington State. Samples were taken from the cow on December 9 as part of USDA's BSE surveillance program. The BSE diagnosis was made on December 22 and 23 by histopathology and immunohistochemical testing at the National Veterinary Services Laboratory, Ames, Iowa. The diagnosis was confirmed by an international reference laboratory in Weybridge, England, on December 25. Preliminary trace-back based on an ear-tag identification number suggests that the BSE-infected cow was imported into the United States from Canada in August 2001.
USDA, in close cooperation with Canadian agricultural authorities, has launched an epidemiologic investigation to determine the source of the disease. Beef from the slaughtered cow had been processed for human consumption. On December 23, 2003, the Food Safety and Inspection Service (FSIS), USDA announced the recall of all beef from cattle slaughtered on December 9 at the involved slaughter plant.
Strong evidence indicates that BSE has been transmitted to humans primarily in the United Kingdom, causing a variant form of Creutzfeldt-Jakob disease (vCJD). In the United Kingdom, where over 1 million cattle may have been infected with BSE, a substantial species barrier appears to protect humans from widespread illness. As of December 1, 2003, a total of 153 vCJD cases had been reported worldwide; of these, 143 cases had occurred in the United Kingdom. The risk to human health from BSE in the United States is extremely low.
CDC monitors the trends and current incidence of CJD in the United States by analyzing death certificate information from U.S. multiple cause-of-death data compiled by the National Center for Health Statistics. With the support of the Council of State and Territorial Epidemiologists, CDC conducts follow-up review of clinical and neuropathology records of CJD decedents younger than 55 years of age. In addition, during 1996-1997, in collaboration with the American Association of Neuropathologists (AANP), CDC established the National Prion Disease Pathology Surveillance Center at Case Western Reserve University in Cleveland, Ohio. This pathology center provides free, state-of-the-art diagnostic services to U.S. physicians. It also helps to monitor the possible occurrence of emerging forms of prion diseases, such as vCJD, in the United States. For more information about the center visit its website at: http://www.cjdsurveillance.com.
For additional information about the case of BSE in Washington State and general information on prion diseases, see the following websites: