Mad Cow Disease
Bovine spongiform encephalopathy (BSE), better know as Mad cow disease is a relatively new disease. Most sources state that BSE first showed up in Great Britain in 1986 [Dealler p.5] but some say it popped up in 1985 [Greger p.1]. However the official notification was not until 21 June, 1988 [Dealler stats. p.1]. Spongiform encephalopathies are invariable fatal neurodegenerative diseases and there is no treatment nor is there a cure for this disease [Greger p.1]. The recent scare of BSE has arisen because of the contraction of Creutzfeldt-Jakob disease (CJD: see Appendix B) in humans from eating beef products. Although there are many forms of Spongiform encephalopathies that affect a wide range of animals, BSE has received the most attention because many people in the world consume beef and people are that they might contract the disease from eating a burger at their favourite fast-food restaurant. In this essay I will discuss BSE and other forms of Spongiform encephalopathies, how it affects the ani mal, what causes the animals to contract the disease, and the recent issues of BSE in the world. I hope to set out the true facts about BSE and that it only affects a small percent of the world population. Due to the fact BSE is a new disease most of my information might be proven wrong in the future because there is a great deal of testing going on in the scientific community. They are also very concerned about this new disease and the effects it can have on humans if it is not stopped.
Bovine spongiform encephalopathy is not some bacteria and it is not a virus, but in fact it is an infectious protein or prion [Greger p.2]. Before I go into more detail, I would like to discuss what a prion is. A prion is composed solely of proteins, and lacks genetic material in the form of nucleic acids. They are the tiniest infectious agents known, they can only be viewed under the strongest of electron microscopes [see appendix A]. Most scientists are puzzled because nucleic acid is the basis reproductive material needed in all other life forms [Britannica vol.9 p. 978]. Because of their unique makeup, prions are practically invulnerable. They can survive for years in the soil. Chemical disinfectants, weak acids, DNAase, RNAase, proteinases [Dealler p.8], ultraviolet light, ionising radiation, heat, formaldehyde sterilization, and chemicals that react with DNA [Greger p.2], all have little effect on the infectivity of the prion. Only marinating your hamburger in Drain-O would make your burger safe to eat [Greger p.2].
BSE, is a slowly progressing degenerative disease affecting the central nervous system of cattle. BSE is the same as most of the other spongiform encephalopathies, they evoke no immune response and consequently slowly accumulate for an incubation period up to 30 years. You cannot detect them, purify then, nor can you isolate them [Greger p.2]. One of the main issues that affect most farmers is how do they know if a cow has BSE. Cattle affected by BSE develop a progressive degeneration of the nervous system. Affected animals may display changes in temperament, such as nervousness or aggression, abnormal posture; incoordination and difficulty in rising, decreased milk production, or loss of body condition despite continued appetite [Kent p.10]. However it has been noted the signs in American cows is much different. They instead stagger to their death like downer cows do. "A downer cow" is referring to the industry term which describes cows who fall down and are too sick to get up [Greger p.4]. There is no treatment so all affected cattle die. The incubation period ranges from two to eight years [Hodgson p.2]. Following the onset of clinical signs, the animal's condition deteriorates until it dies or is destroyed. This usually takes from two weeks to six months. Most cases in Great Britain have occurred in dairy cows between three and five years of age [Dealler Bio p.7]. The parts of the cow...
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