Mad Cow Disease


What exactly is Mad Cow disease? Mad Cow, otherwise known as bovine spongiform encephalopathy (BSE), is a degenerative disorder of the brain found in cattle, caused by a mostly unknown agent. This disease causes brain cells to die, causing sponge-like holes in the cow’s brain. This causes the to act very strangely. It acts crazy or “mad” causing death within a year. If this disease affects cattle, why should we be worried about it? A variation of a brain disorder found mostly in elderly people called Creutzfeldt-Jakob Disease (CJD), has been found in some younger people. The variation is properly called New Variant Creutzfeldt-Jakob Disease (nvCJD). Most nvCJD patients die within one year of onset (CDC). Some things that we need to know in order to stop this disease are it’s origins, what it does, and what we can do to prevent it’s spread.


There are many different hypothesis’ of the origins of nvCJD. According to Dr. Frederick A. Murphy, Dean of the School of Veterinary Medicine, “BSE was initially recognized in cattle in the UK in 1986” (Henahan). It has never been proven but is widely believed that BSE originally came from a 200 year old disease. “BSE is thought to have come from a similar disease in sheep called scrapie”( Freudenrich). In the 1980’s cattle farmers who created cattle feed changed the way they manufactured it. The feed originally contained by-products from sheep. The change in the manufacturing process somehow allowed the Scrapie disease agent to pass through. As a result, cows which ate this feed became affected by this and received BSE. According to Dr. Murphy, “The epidemic in cattle in Britain reached incredible proportions; by 1993 more than 1,000 cases per week were being reported. More than 160,000 infected cows have now been identified, involving more than 50% of the dairy herds in the UK.” As you could imagine, the infected meat found it’s way to the human population in the form of nvCJD. According to the Center for Disease Control, “There has never been a case of nvCJD that did not have a history of exposure within a country where this cattle disease, BSE, was occurring” (CDC). Furthermore, the brains of nvCJD victims had proteins called prions which were very similar to those that were found in the brains of BSE infected cows. These prions were also slightly different than the ones that were found in the originalCJD(which affected mostly elderly people). As a result, it is very widely believed that nvCJD happened to be a rare disease which happened to pass from animal, to human. But how does nvCJD work and what does it to do people?


The definitive answer as to how nvCJD works is not certain. However, there is a hypothesis which is widely believed to be true by the scientific community. It is believed that nvCJD is caused by a prion. “It was Stanley Prusiner of the University of California, San Francisco, who first discovered the nature of prions” (Henahan). Prions are nothing more than rogue or misshapen proteins. The problem is that these rogue proteins change the shape of normal proteins. According to Dr. Craig C. Freudenrich Ph.D.:


A person ingests an abnormally-shaped prion from contaminated food. The abnormally-shaped prion gets absorbed into the bloodstream and crosses into the nervous system. The abnormal prion touches a normal prion and changes the normal prion's shape into an abnormal one, thereby destroying the normal prion's original function. Both abnormal prions then contact and change the shapes of other normal prions in the nerve cell. The nerve cell tries to get rid of the abnormal prions by clumping them together in small sacs that merge with its "stomach" (lysosome). Because the nerve cells cannot digest the abnormal prions, they accumulate in the lysosomes. The lysosomes grow and engorge the nerve cell, which eventually dies. When the cell dies, the abnormal prions are released to infect other cells. Large, sponge-like holes are left where many cells die. Numerous nerve cell deaths lead to loss of brain function, and the person eventually dies. There has never been a document case of nvCJD in which it was passed from human to human” (Freudenrich).


Since nvCJD has many characteristics not seen before in any other disease, many special precautions