BOX 3-4
Single Case of Bovine Spongiform Encephalopathy (BSE) in Washington State: An Unexpected Opportunity for Insight into Our Framework for Preventing, Detecting, and Diagnosing Animal Diseases

On the morning of December 25, 2003, the BSE World Reference Laboratory in Weybridge, England, confirmed USDA’s December 23 preliminary diagnosis of BSE in a single nonambulatory dairy cow that had been slaughtered on December 9 at Vern’s Moses Lake Meats in Washington State. USDA and Canadian officials worked together to confirm the identification of this cow through DNA testing and to establish that the animal was imported from Canada.

BSE (or “mad cow” disease) is a neurodegenerative disease transmitted to cattle through contaminated feed. It has an incubation period of 4–6 years. It is caused by an aberrant form of a protein called a prion and is in the family of diseases—all caused by prions—referred to as transmissible spongiform encephalopathies, or TSEs. The prion is an abnormally folded version of a normal cellular protein. The abnormal conformation results in a phenotype that is highly resistant to degradation and can persist in an infectious form during the rendering of contaminated bovine by-products for animal feeds, and the preparation of other products such as cosmetics and drugs using ingredients derived from cattle.

Unlike other agents (such as FMD virus), the prion is not contagious. Although it is considered “infectious,” it is not spread directly from one animal to another. It carries a low risk of spreading to animals in the United States (Harvard risk assessment). The overall public health risk of develop-

supply of meat can shake consumer confidence, resulting in reduced demand, and can significantly disrupt trade of meat and meat products for a prolonged period. Establishing countrywide disease-free status once a case is diagnosed can be extremely difficult. According to a panel of experts from the European Association for Animal Production, the estimated total cost of BSE in Europe is €92 billion, nearly $115 billion dollars (EAAP, 2003). It had been estimated that a single case of BSE in either Canada or the United States would cost their respective beef industries $3.3 billion CAD and $6 billion USD, respectively (CBC News, 2003; Presley, 2004).

The onset of BSE in Great Britain led the United States to carry out an extensive analysis and forge policies based on risk factors associated with the disease, even though the disease was not present; this marked a significant departure from the past (USDA APHIS-VS, 1991). Trade in animal feed has been extensive in North America. Rendered by-products



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement