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:
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