BSE Cases Identified in the United States
There have been 6 cases of BSE identified in the United States. The following information provides descriptions of these 6 cases:
On August 29, 2018 the U.S. Department of Agriculture (USDA) announced a confirmed atypical, H-type case of bovine spongiform encephalopathy (BSE) in a six year old mixed-breed beef cow in Florida. USDA reported that this animal never entered the food supply and at no time presented a risk to human health. See the USDA noticeExternal.
On July 18, 2017, the U.S. Department of Agriculture (USDA) announced the confirmation of the fifth case of bovine spongiform encephalopathy (BSE) in an 11-year-old cow in Alabama. The cow was found through USDA’s routine surveillance. The cow was found to be positive for an atypical (L-type) strain of BSE. Atypical BSE usually occurs in older cattle and seems to arise spontaneously in cattle populations. See the USDA noticeExternal.
On April 24, 2012, the USDA confirmed a BSE case in a dairy cow in California. This cow was tested as part of the USDA targeted BSE surveillance at rendering facilities in the United States. The cow was 10 years and 7 months old and was classified as having the L-type BSE strain.
For more information, see the USDA/APHIS noticeExternal, and the Summary Report, California Bovine Spongiform Encephalopathy Case Investigation Cdc-pdf[PDF – 179 KB]External.
On March 15, 2006, the USDA announced the confirmation of BSE in a cow in Alabama. The case was identified in a non-ambulatory (downer) cow on a farm in Alabama. The animal was euthanized by a local veterinarian and buried on the farm. The age of the cow was estimated by examination of the dentition as 10 years old.
It had no ear tags or distinctive marks; the herd of origin could not be identified despite an intense investigation (see Alabama BSE Investigation, Final Epidemiology Report, May 2006 Cdc-pdf[PDF – 105KB]External).
In August 2008, several ARS investigators reported that a rare, genetic abnormality that may persist within the cattle population “is considered to have caused” BSE in this atypical (H-type) BSE animal from Alabama. (See Identification of a Heritable Polymorphism in Bovine PRNP Associated with Genetic Transmissible Spongiform Encephalopathy: Evidence of Heritable BSEExternal. Also see BSE Case Associated with Prion Protein Gene MutationExternal.)
On June 24, 2005, the USDA announced receipt of final results from The Veterinary Laboratories Agency in Weybridge, England, confirming BSE in a cow that had conflicting test results in 2004. This cow was from Texas, died at approximately 12 years of age, and represented the first endemic case of BSE in the United States. (see Texas BSE Investigation, Final Epidemiology Report, August 2005 Cdc-pdf[PDF – 82KB]External)
On December 23, 2003, the U.S. Department of Agriculture (USDA) announced a presumptive diagnosis of the first known case of BSE in the United States. It was in an adult Holstein cow from Washington State. This diagnosis was confirmed by an international reference laboratory in Weybridge, England, on December 25. Trace-back based on an ear-tag identification number and subsequent genetic testing confirmed that the BSE-infected cow was imported into the United States from Canada in August 2001.
Because the animal was non-ambulatory (a “downer cow”) at slaughter, brain tissue samples were taken by USDA’s Animal and Plant Health Inspection Service as part of its targeted surveillance for BSE. However the animal’s condition was attributed to complications from calving. After the animal was examined by a USDA Food Safety and Inspection Service (FSIS) veterinary medical officer both before and after slaughter, the carcass was released for use as food for human consumption. During slaughter, the tissues considered to be at high risk for the transmission of the BSE agent were removed.
On December 24, 2003, FSIS recalled beef from cattle slaughtered in the same plant on the same day as the BSE positive cow. (see Bovine Spongiform Encephalopathy in a Dairy Cow—Washington State, 2003.)
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 CenterExternal 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:
For more information about BSE in the United States, see the Animal and Plant Health Inspection Service, USDA BSE siteExternal.