The Possible Mechanisms of Scrapie Contraction Essay -- Biology Medica

The Possible Mechanisms of Scrapie Contraction Scrapie was first discovered in Great Britain in the late 1900’s. The first case of scrapie in the United States was found in Michigan in 1947 when the flock owner had imported sheep of British origin several years prior. Since then scientists have researched to find the cause of the scrapie agent that are classified as transmissible spongiform encephalopathy. At the present, scientists have presented three main theories that explain why the scrapie agent holds a dangerous threat against its host and how it elicits its symptoms. Scientists are finding genetic alternatives to prevent and dampen the spread of scrapie within sheep and goat flocks. They use methods such as tatoing and genetic selection to regulate animals exposure to the pathogen. Scrapie is defined as a fatal, degenerative disease affecting the central nervous system of sheep and goats. It is widely feared because of its uncertain origin and therefore its seemingly incurable status. It is closely related and often associated with bovine spongiform encephalopathy (BSE; also known as â€Å"Mad Cow† disease), as well Chronic Wasting Disease (found in deer and elk) all of which are classified as transmissible spongiform encephalopathy. (Q&A. July 2005 http://www.animalagriculture.org/scrapie/AboutScrapie/QandA.htm) Scrapie is usually transmitted from the mother to her baby sheep or goats, through the placenta or the placental fluids. Animals infected with scrapie experience the symptoms and effects of the disease after two to five years post infection. Scrapie can be transmitted to susceptible sheep and goats through contact with the placenta and placental fluids of infected animals. There has been no evidence of human trans... ...entists alike are trying to make up new procedures of prevention to dampen the further spread of scrapie throughout the population of sheep and goats. Such measures taken to prevent the spread of scrapie include the genetic-based flock clean up plan. Here, genetic selection is used as the primary means of scrapie regulation. The United State s Department of Agriculture’s Animal Plant Health Inspection Service is using genetic testing to determine which exposed animals must be removed or restricted in affected flocks and which are free to move unrestricted. This genetic clean up plan calls for the removal or restriction of all exposed susceptible sheep and goats as well as a five-year cycle of strict monitoring for the breeding of all the livestock (The Genetics of Scrapie Susceptibility. July 26 2005: http://www.aphis.usda/gov/us/nahps/scrapie/scrapie_genetics.pdf).