Basics of Bovine Spongiform Encephalopathy – Mad Cow Disease


Bovine Spongiform Encephalopathy (BSE) is also commonly known as Mad Cow Disease. BSE is caused from an infection from a mutated protein (known as a prion) that attacks the central nervous system of the bovine. The prion basically turns the spinal cord and eventually the brain into a “spongy” appearance – hence giving it the “spongiform” name.

A prion is virtually indestructible. Unlike most other bacteria and contaminates that can be destroyed by cooking thoroughly, heat does not affect the prion. It has been theorized that the bovine spongiform prion is a mutated version of “Scrapie”, the spongiform disease of sheep.

Sheep waste and byproducts derived from slaughtering establishments – then rendered and fed back to cattle as protein – is most sensible idea as to how Scrapie was transferred to cattle.

Cases of Mad Cow Disease

Since 2003, there have been only three cases of BSE in the United States that were positively identified. On December 23, 2003 the first case was positively identified in Washington State (further tests showed positive on December 25, 2003). The next case was on June 24, 2005, and this cow was from Texas. Then on March 15, 2006 a cow in Alabama was tested Positive for the disease. No other contaminated carcasses have been detected since 2006.

When cases of BSE began to show in the United States, the USDA and FSIS put together a “game plan” to help eliminate the possibility of spreading the disease through rendering plants and back into the food chain. The initial step was to determine a way for slaughtering establishments and Inspection Personnel working these establishments to identify cattle by their age using dental detention and segregating the older from the younger cattle.

Eliminating Bovine Spongiform Encephalopathy or Mad Cow Disease

Typically, BSE does not mature in cattle until the cattle are around 30 months of age. With this known, dental detention was used to determine age of cattle.

The next step was to eliminate any parts and components (specified risk materials) of carcasses that could possible contain BSE infection. Since BSE was a spongiform disease and attacked the central nervous system – specifically in cattle 30 months of age or greater – spinal columns, heads, and parts of the small intestine must not enter the consumer food supply. If these components are derived from cattle less than 30 months of age and pass Inspection, they are acceptable for consumption.

Many rendering plants are no longer accepting Specified Risk Materials due to Food and Drug Administration issuing laws and regulations preventing rendering plants from processing these materials. Although this does help eliminate the possibility of SRMs from entering the rendering plants from cattle greater than 30 months of age, it puts the burden of disposing the product on the slaughtering processor. Still, this is a good method to help eliminate the disease from entering commerce.

USDA/FSIS Regulations on Bovine Spongiform Encephalopathy

The regulations issued by the USDA required slaughtering and processing facilities to separate cattle greater than 30 months of age from those less than 30 months of age. This started from the time the cattle were stored in pens awaiting slaughter, to the time they were processed.

Other rules were also created to further eliminate contamination from any cattle that were potentially contaminated with the product. These rules included methods of product handling, Specified Risk Materials, Advanced Meat Recovery Systems, and Air Injected Stunning methods.

A recordkeeping system also had to be implemented showing documentation of every bovine received for slaughter at the slaughtering establishment, as well as disposal of all Specified Risk Materials during slaughter and processing. This applied to all slaughtering establishments – Inspected or Custom.

Since these regulations have been required by USDA, many establishments have implemented BSE Checks in their HACCP and SSOP Food Safety Systems.

Bovine Spongiform Encephalopathy in Humans

The spongiform disease that is found in humans is known as Creutzfeldt-Jakob Disease (CJD). This particular disease is incurable and is linked to humans eating cattle that are infected with Bovine Spongiform Encephalopathy. Although this disease is extremely rare, Creutzfeldt-Jakob Disease affects about one person in every one million people per years.

There are around 200 cases of this disease per year in the United States with symptoms usually those of individuals showing problems with muscle coordination; depression; impaired judgment and memory; and impaired vision. Other symptoms may include involuntary muscle jerks and blindness is possible!

With the strict USDA regulations implemented, the cases of BSE in cattle and CJD in humans should decline over the next several years. Cattle greater than 30 months of age will continue to be slaughtered and the products derived from these cattle will continue to safely enter the food chain.


  • Center for Disease Control and Prevention, BSE (Bovine Spongiform Encephalopathy, or Mad Cow Disease), August 26, 2010
  • United States Department of Agriculture, Food Safety Inspection Service, USDA Issues New Regulations to Address BSE, January 8, 2004
  • FSIS/UDSA, Enhancing and Evolving: Advancements in 2003 and USDA’s Initiatives to Improve Food Safety in 2004, February 12, 2004


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