Bovine Spongiform Encephalopathy / Mad Cow Disease

Compiled by Doug Mayo, Jackson County Extension


What is BSE?

Bovine Spongiform Encephalopathy (BSE, 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 cattle infected 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. There has not been a case of vCJD in the US from consuming US Beef.

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.

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BSE Talking Points for US Cattlemen

  1. BSE is not found in beef or milk. The "prion" or BSE infectious agent has only been found in nervous tissue, brain, eyes and small intestine. The recent meat recall was an act of an "abundance of caution" by USDA to ensure consumer confidence.
  2. BSE is not spread from animal to animal, so this disease is not spreading. BSE is spread through the feeding of BSE contaminated ruminant animal by-product protein feeds to ruminant animals (meat and bone meal). The US banned the feeding of ruminant animal meat and bone meal to cattle in 1997.
  3. This was one cow, not an epidemic like we saw in England. USDA has been testing for BSE since 1990 (13 years) and tested over 57,000 head with only one positive cow.
  4. All US cattle are inspected by a certified USDA veterinarian or inspector prior to slaughter.
  5. All animals exhibiting any sign of a neurological disorder or unable to walk have been tested for BSE for 13 years. Now that we have had a positive case, no meat will enter the human food chain until a suspect carcass receives a negative BSE test.
  6. Non-ambulatory "downer" cattle will no longer be slaughtered for human consumption.
  7. USDA inspectors ensure that central nervous system tissue from older cattle does not enter the human food chain. New USDA regulations are further strengthening the firewalls currently in place to ensure that specific risk materials from carcass of cattle over 30 months old do not enter the human food chain.
  8. Beef and live cattle imports from nations outside the US known to have BSE have been banned since 1989.
  9. BSE cow came from Canada. Technically the US still has not had a BSE case from cattle born in the U.S. Canada has only had 2.
  10. In 2001, Harvard University conducted an independent risk assessment of the spread of BSE in the US and found that "the US is highly resistant to the spread of BSE" due to the protective measures that were in place.
  11. The surveillance system developed by USDA for BSE worked and the cow was tested.
  12. Until December the US never had a positive BSE case, now even stronger measures are being implemented to ensure BSE does not enter the human food chain.
  13. There are no 100% safe guarantees. We can’t say that there is zero risk, but USDA is strengthening firewalls that reduce the risk to as near zero as possible.

New USDA Regulations for the Beef Industry

  • Downer Cows No Longer Accepted
    – If a cow cannot walk on her own into the slaughter plant, she can’t be processed for human consumption.
  • Ban on Specified Risk Materials
    – Parts of the cow know to harbor BSE infectious agents: brain, skull, eyes, spinal cord, small intestine, tonsils of cattle 30 months old or older.

    • Some slaughter plants have instituted up to $50 discounts on cattle 30 months old and over.

  • Ban on Blood Meal
    – Meat and bone meal have been banned since 1997, but now blood meal will be prohibited as well.
  • Ban on Feeding Poultry Litter
    – Chickens can be fed animal by-product protein feeds and there could be spilled feed included in the poultry litter.
  • Ban on Plate Waste
    – Restaurant waste will not be allowed in ruminant animal feeds because FDA would not be able to adequately test feeds for prohibited proteins.
  • Ruminant and Non-ruminant Feed Facilities
    – To prevent cross contamination, feed companies will have to use separate equipment, facilities and production lines for the two types of feeds.
  • Product Holding
    – Now that we have had a positive BSE case, no suspect carcasses will be processed without negative test.

    • This prevents another meat recall from BSE cattle.

  • Increased Surveillance
    – USDA will increase BSE testing from 20,000 head annually to 40,000 over the next two years.

    • President Bush announced a $60 million budget for BSE in 2005, $47 million increase over 2004 budget.

  • Mandatory Animal ID
    – $33 million of Bush’s 2005 budget for animal ID

    • 2004 Premise ID
    • 2005 Interstate Movement
    • 2006 All Movement

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Credible Links for More Information About BSE

Information about BSE, the national testing program, and new regulations.

  • USDA Updates
    USDA's home web page with the latest press releases
  • NCBA Updates
    NCBA's Industry News with statements regarding the latest press releases
  • USDA's BSE Surveillance
    USDA's BSE ongoing disease surveillance
    USDA's Animal and Plant Health Inspection Service Web site with basic general information about the disease BSE or Mad Cow Disease
    The Food and Drug Administration's Web site with BSE information for consumers
    The Center for Disease Control's Web sites on BSE and Creutzfeldt-Jakob Disease
    National Cattlemen's Beef Association BSE information Web site
    Extension Disaster Education Network BSE resource and information page
  • Iowa Beef Center BSE
    Iowa State University's Beef Center Web site with information for producers related to BSE
  • PU Experts on BSE
    Purdue University Specialists comment on the potential affects of the BSE case
  • UI BSE Scintific Data
    The University of Illinois scientific research information site on BSE
  • Canada BSE
    The official BSE Web site of the Canadian Government
  • England BSE
    The official BSE Web site of the English Government

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