The Effects of Transmissible Spongiform Encephalopathies on Humans
Abstract
Humans have to deal with many different diseases and the ones most disliked are the ones with no cures. Like cancer, transmissible spongiform encephalopathies have no cure, but they are more rare. These diseases are prion diseases which cause the brain to deteriorate. Prions are proteins that sometimes behave like viruses, which mean that they should have some form of nucleic acid, but since they don’t, they cause abnormalities. The nervous system contains many normal prions, but when an abnormal prion comes along, it transforms all the normal prions into abnormal ones. Bovine spongiform encephalopathy is found in cattle, but it can be transmitted to humans. The Creutzfeldt-Jakob disease affects the elderly for reasons unknown, while Kuru affects those who practice cannibalism. Scrapie is found only in sheep and the Chronic Wasting Disease is found in deer and elk. As of right now, Kuru and Scrapie are not known to infect humans.
Prion diseases affect many animals, such as cattle, sheep, deer, elk and humans. All mammals have prions, which are proteins that are found abundantly in the nervous system. The brain contains the most prions and is therefore dominantly affected by disease. The prion disease found in cattle is called bovine spongiform encephalopathy, or mad cow disease. Humans contract this disease by eating infected cows. The elderly usually contract the Creutzfeldt-Jakob disease for reasons unknown, and Kuru, which is extremely rare nowadays, is contracted by cannibalism. Scrapie infects sheep and the Chronic Wasting Disease infects deer and elk. Though there is no link to either Scrapie or Chronic Wasting Disease infecting humans, it is ...
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...missible Spongiform Encephalopathies 6
References
• American Veterinary Medical Association. (2002, May). About Scrapie. Journal of the American Veterinary Medical Association. 7/25/05: http://www.avma.org/onlnews/javma/may02/s050102i.asp
• Australian Academy of Science. (1997, February). Mad Cow Disease-A Human Problem? Science. 7/25/05: http://www.science.org.au/nova/003/003key.htm
• CBC. (2003, December). Science and Symptoms. CBC News. 7/26/05: http://www.cbc.ca/news/background/madcow/science.html
• University of Toronto. (2003, June). Researchers Discover Possible Diagnosis, Treatment, Vaccine for Mad Cow, Prion Diseases. Science Daily. 7/26/05: http://www.sciencedaily.com/releases/2003/06/030602025719.htm
• U.S. National Library of Medicine. (2005, February). Prion Disease. Genetics Home Reference. 7/26/05: http://ghr.nlm.nih.gov/condition=priondisease
In the subsequent essay I will discuss and explain the relative function of the Prion protein. The Prion protein, also known as PrPC, ‘’is a membrane-anchored protein with two N-glycosylation sites and, although it is highly expressed in the nervous tissues, its physiological functions have yet to be well established’’ (Coordination Chemistry Reviews). PrPC/PrP is found in healthy brains in this form, and consists of 250 Amino Acids, yet after a simple misfolding in the secondary structure; this can alienate the PrP and forms PrPsc, which is the abnormal form of the Prion protein. The infectious agent PrPsc causes neuropathological changes in the brain, and instantly places the individual under the category of someone with the prion disease. PrPsc forms insoluble fibres and thus cannot be studied well using Nuclear Mass Resonance (NMR), and it is also more resistant to protease digestion. Furthermore, ‘’ The transmissible spongiform encephalopathies (TSEs) arise from conversion of the membrane-bound prion protein from PrPC to PrPSc, the latter being the scrapie form. Examples of the TSEs include mad cow disease, chronic wasting disease in deer and elk, scrapie in goats and sheep, and kuru and Creutzfeldt-Jakob disease in humans’’ (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2904554/. 2014). The following diagram shows the conversion from PrPc to PrPsc:
Mad Cow Disease, scientifically referred to as (BSE) Bovine Spongiform Encephalopathy, is a disease that affects those humans who eat the meat from infected cows. Mad Cow Disease is one of several fatal brain diseases called (TSE) Transmissible Spongiform Encephalopathy. (USDA) There was evidence of a new illness resembling the sheep disease scrapie. It was technically named BSE but quickly acquired the mad cow tag because of the way infected cattle behave. (CNN) In 1997, there was an award given to Stanley Prusiner, for concluding that a distorted protein called a prion was responsible for Mad Cow Disease, noted the long incubation period made it difficult to distinguish (Bryant). Another name for Mad Cow Disease is the new variant Cruetzfeldt-Jakob Disease (vCJD), similar to the Creutzfeldt-Jakob Disease, which is a deadly brain illness that strikes about one per million per year (USDA) due to genetic or unknown causes while the vCJD is contracted from eating infected cows (USDA). Both CJD and vCJD are so similarly named because of the similar effects from the illness.
Mad cow disease is caused by prions, "weird mutant proteins that are found in brain and spinal tissue"1. Another name for mad cow disease is called bovine spongiform encephalopathy (BSE) and the definition is "a progressive neurological disorder of cattle that results from infection by an unusual transmissible agent called a prion"2. It started from what is called a prion protein then it turned into a pathogenic, and then it starts to damaged the brain of a cattle. There's another name for this disease and it's called Creutzfeldt-Jakob Disease "a form of progressive dementia characterized by loss of nerve cells and degeneration of nerve cell membranes leading to the production of small holes in the brain. It is rare, degenerative, and invariably fatal"3. This disease happen in human causing lapses in the memory, mood swings similar to depression, lack of interest and social withdrawal3. It is said that this disease has no tr...
Plenty of people love the fact that they can enjoy life normal because their brain functions accordingly. Well not every one has the gift of normality. In this harsh world people are dying of all types of diseases and things that are undetectable or even treatable due to the fact that they have unknown origins. Many of the world’s diseases such as HIV, AIDS, some cases of Multiple Sclerosis and Muscular Dystrophies. Among these fatal and life threatening ailments Creutzfeldt-Jakob disease, other wise known as (CJD), takes precedence.
Chronic Wasting Disease (CWD) is a fatal neuro-degenerative, transmissible spongiform encephalopathy (TSE) of the family Cervidae (Hamir, et.al., 2006). The family Cervidae includes mule deer, Odocolileus hemionus, white-tailed deer, Odocolileus virginianus, Rocky Mountain elk, Cervus elaphus nelsoni, and moose, Alces alces shirasi, among others (Sigurdon & Aguzzi, 2007). CWD is a prion disease, meaning it is a protein caused infection, that occurs naturally in the deer family (Song & Lawson, 2009). This protein is suspected to be an abnormal isoform (PrPSc) of the naturally occurring host prion protein (PrPC) (Blanchong, et. Al., 2009). Bovine spongiform encephalopathy (BSE), mad cow disease, is a similar prion effecting cattle as CWD affects Cervidae. Although, scientists are not sure of transmission route it is suspected that CWD is transmissible and infectious through direct contact with infected individuals or through environmental contamination (Song & Lawson, 2009). Tests have been performed showing susceptibility of altered mice to oral transmission, mimicking the suspected route of entry, and the incubation appears slower but lasts longer with oral infection (Trifilo, et.al., 2007). The approximate time from the initial infection to death is three years.
Normally, cows in Northern Europe in places such as Denmark live normal lives simply grazing on grass, and existing. However, there have been recent changes that have disrupted this normal activity. Generally the bluetongue virus (spread by Culicoides imicola, a biting midge) has been confined to Southern Europe and other places around the Mediterranean. But with the increase in temperature throughout the area, the midge has been allowed to migrate northward. This new pest is a nuisance and causes lots of difficulties to farmers in the area. When a cow contracts this disease, they usually also receive oral ulcers, salivation, stiffness, fever and eventually the inevitable- death (Merck Veterinary Manual NP). Because of the increase in temperature, midges have spread around the globe infecting livestock and creating terrible trouble for many farmers.
There are currently a number of studies being performed on the potential effects of Chronic Wasting disease on human health. So far, CWD has only been transferred outside of the cervid family in laboratory settings by intracerebral injections. There have not been any cases of increased human prion diseases in CWD endemic areas, nor is there currently any evidence indicating humans can contract the disease. Because of the long incubation period of CWD, more studies and years of follow ups are necessary to fully determine if human health can be affected by this disease. As of now, however, there is no evidence that humans or even other animals are affected by Chronic Wasting Disease.
Korth, C., Streit, P., & Oesch, B. (1999). Monoclonal Antibodies Specific for the Native, Disease-Associated Isoform of the Prion Protein. Methods in ENZYMOLOGY: , 309, 106-122 .
Autopsies of affected cattle reveal holes in the brain tissue that give it a spongy, or spongiform, texture. Similar spongiform diseases have been recognized in humans (for example, Creutzfeldt-Jakob disease or CJD) for over a century and in sheep (scrapie) for over 200 years. The cause of BSE is unproven, although there is strong evidence that prions, which may be infective proteins, are the agent. Other hypotheses suggest that prions work with an as yet undetected virus to cause the infection.
If you had to choose between having Mad Cow Disease or becoming the top scientist in your field, which would you choose? The answer is obvious. Most realize that Mad Cow Disease, i.e. Bovine spongiform encephalopathy, is a fatal disease that has been present among cattle populations in Europe over the past couple decades. In BSE, brain cells begin to die, forming sponge-like holes in the cow’s brain tissue. Evidence shows that consumption of infected cattle could correspond with the contraction of Creutzfeldt-Jakob Disease (CJD), a similar disease in humans. Although few people have been diagnosed with CJD worldwide, they remain fearful of showing symptoms of CJD; commonly resulting in death within a year. For this reason, many Americans panicked when becoming aware that the first case of BSE was discovered in the United States in December of 2003. Unfortunately, the media is quick to show infected cows, distempered and shaking in their stalls, without giving sufficient information of the disease’s origin or the preventative measures being taken to halt its spreading. Before consumers restrict beef intake from their diets they should consider their risks. In America, chances of developing BSE is far slimmer than becoming infected with other food-borne illnesses. Although many Americans were recently startled by a reported case of Mad Cow Disease in the United States, they are assured protection from infection by: consumption of selected meats, closely guarded packaging plants, and regulation in beef imports.
Mad cow disease, also knows as BSE (Bovine Spongiform Encephalopathy) is an transferable disease which slowly attacks the brain and nervous system of cattle. There isn’t any cure for the disease. The first case of BSE in Canada was a cow that had been imported from the United Kingdom in 1987 at the age of six months. The animal was destroyed upon the discovery of the disease and the Canadian government banned imports from the United Kingdom. This report relates to unit 4 in terms of the economic and industrial overview of the disease in Canada. This report is on the second discovery of mad cow disease in Canada and how it affected Canada economy and Alberta’s beef industry.
Mad Cow Disease, also known as BSE (bovine spongiform encephalopathy), is a slowly progressive, fatal neurological disorder in cattle that results from infection by a prion. Research indicates that the first probable infection of BSE in cows occurred during the 1970's. BSE possibly originated as a result of feeding cattle meat-and-bone meal that contained BSE-infected products from a spontaneously occurring case of BSE. Evidence suggests that the outbreak spread throughout the United Kingdom cattle industry by feeding prion-infected, bovine meat-and-bone meal to the young calves (Mad Cow Disease Facts). There was strong laboratory evidence between the BSE outbreak in cattle and a human prion disease called variant Creutzfeldt-Jakob disease (vCJD) that was first reported in the United Kingdom (UK) in 1996. The disease is caused by eating beef products contaminated with central nervous system tissue from cattle infected with Mad Cow Disease. It can affect all age groups and is very hard to diagnose until it has nearly run its course. VCJD is fatal, usually within 13 months of the onset of symptoms (The Basics of Mad Cow Disease). The impact Mad Cow Disease and vCJD had in the United Kingdom caused fear worldwide and resulted in major changes to be implemented in the cattle industry.
...The fact that one's neural communication is severed and eventually shuts down all body function control, is evident. The knowledge that one's brain is "riddled with holes" due to a proteinaceous infectious particle is speculative. Although many think that an individual is much more than mere neural connections, firing motor symphonies, neurotransmitters, and selective permeability, Creutzfeldt-Jakob disease puts a new spin on individual identity. Ultimately, the patients or their loved ones do not focus on the CJD facts and figures. Their reality is that an individual slowly disintegrates before their eyes, the sense of "the Self" is lost.
Prion Disease is an illness that many have not heard about. This is sad because many have died and are dying from this disease that doesn’t yet have a cure. “Prion Disease is a group of conditions that affect the nervous system in humans and animals… these conditions impair brain functions, causing changes in memory, personality, and behavior; a decline in intellectual function (dementia); and abnormal movements particularly difficulty with coordinating movements (ataxia)” (Genetics Home Reference). This is basically the definition of what Prion Disease is and without going into depth it explains how it affects the person that is affected. “In t...
This paper will talk about super cows and the ups and downs of their modification.They are miserable their whole and die painfully. Although it make low allergy milk which some people may need. No one I know wants to live in pain everyday of their life neither do these cows.