Mad Cow Disease
BSE
Bovine Spongiform Encephalopathy--aka Mad Cow Disease--is a slowly progressing fatal disease that affects the central nervous system in cattle. The disease is believed to be caused by an abnormal or altered protein called a "prion" in the brain. The disease is found almost exclusively in cattle over 2 years old.
The incubation period for this disease ranges from 2-8 years and is always fatal. There is no vaccination available to prevent this disease and there currently is no way to test live cattle for the disease. BSE testing currently is conducted only on brain tissue from slaughtered cattle.
The Reason for So Much Concern
The reason there is such concern about this disease is the possible link between BSE and a rare human disease called Variant Creutzfeldt-Jakob Disease (vCJD). vCJD is a disease of the central nervous system of humans with similar symptoms to BSE. Recent research in England where the disease has been found, supports an association between vCJD and the consumption of products contaminated with nervous system tissue of BSE cattle. The BSE agent has not however, been found in the meat or muscle tissue of infected cattle.
Disease Transmission
The disease is believed to have been transmitted through the feeding of animal by-product feeds, such as meat and bone meal, made from sheep infected with scrapie (a similar disorder in sheep) or from cows with BSE. FDA banned the feeding of animal by-product feeds to cattle in 1997 to prevent transmission of this disease in the US. Also imports of live cattle and cattle products have been banned from countries known to have BSE since 1989.
Cases in the US
Since 1990 USDA has tested 57,352 brain specimens (as of Sept 30,2003) from cattle displaying any possible symptoms of BSE and the cow in Washington was the very first to test positive. USDA has been closely monitoring for this disease for 13 years, so this is not an epidemic but an isolated case.
Clinical Signs of the Disease
Clinical signs of BSE include: temperament changes such as nervousness or aggression, abnormal posture, coordination problems, difficulty in walking or getting up off the ground, decreased milk production, severe muscular twitching, and a loss of body weight despite a good appetite.
Safe for the Consumer
The US Secretary of Agriculture, Ann Veneman gave the following reasons why Americans can be confident in the safety of U.S. beef:
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The BSE agent is not found in meat like steaks or roasts. It is only found in central nervous system tissue, such as, brain or spinal cord.
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All U.S. cattle are inspected by a USDA Inspector or veterinarian prior to harvest. Animals with any signs of neurological disorder are tested for BSE.
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BSE affects older cattle, typically over 30 months of age. The vast majority of the cattle going to market in the U.S. are less than 24 months old.
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The U.S. began a surveillance program for BSE in 1990 and was the first country without the disease within its borders to test cattle for the disease. The surveillance system targets all cattle with any signs of neurological disorder as well as those over 30 months of age and animals that are unable to walk.
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The U.S. banned imports of cattle and bovine products from countries with BSE beginning in 1989.
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The only way BSE spreads is through contaminated feed. The U.S. Food & Drug Administration in 1997 instituted a ban on feeding ruminant-derived meat and bone meal supplements to cattle. This is a firewall that prevents the spread of BSE to other animals if it were present in the U.S.
Secretary Ann M. Veneman ended her statement by saying, "I plan to serve beef for my Christmas dinner."
The following was compiled by Douglas Mayo, Extension Ag Agent in Jackson County
