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 that is affected by BSE are the brain, spinal cord, and retina from
naturally infected animals have been found to be infective and also the lower
ileum (intestine) from experimental cattle inoculated was found to be infective
[Varner p.3].
Great Britain is the site where the major problem of BSE started. The
increase of BSE in the UK was mostly due to the fact that farmers were feeding
their cattle a bovine food which included parts of dead sheep that had scrapie
[see Appendix B.]and also the offal [see Appendix B] of dead cows that carry the
BSE disease. This method of