Is Scrapie like Mad Cow Disease?
221689#0
Scrapie is a fatal, degenerative disease that affects the nervous systems of sheep and goats. It is one of several transmissible spongiform encephalopathies (TSEs), which also includes bovine spongiform encephalopathy (BSE or "mad cow disease"), Creutzfeldt-Jakob disease (CJD) in humans, and chronic wasting disease in deer. Like other spongiform encephalopathies, the cause of scrapie is unknown, but is thought to be caused by an infectious misfolded protein called a prion. Scrapie has been known since 1732, and does not appear to be transmissible to humans.
Scrapie
37887218#4
Scrapie is a fatal infectious disease of the neural system of sheep; one of a class of brain diseases that can affect cattle (BSE) and humans (Kuru, nCJD). Scrapie had been thought to be caused by a 'slow virus' – one that could take years to show as a change in behaviour or movement. By the mid 1960s, it was established that cells could only replicate via DNA. Radioactivity stops cell replication by 'killing' DNA. Alper found that radiation did not kill the infective agent in scrapie, suggesting that a virus was unlikely to be the infective agent. The infective agent had to be smaller and simpler than (viral) DNA. Alper also found that the agent remained active under ultraviolet light. DNA is inactive under UV light. Instead, the agent was killed by light at 237 nm, a wavelength specific to polysaccharide inactivation. Alper and colleagues reported these properties of the scrapie agent – a finding that was greeted with astonishment in many quarters, for it appeared to contravene the central dogma that holds that replication (and hence the growth of the disease and its infectious properties) can only proceed via DNA. However, once these empirical findings were accepted, several theories developed to accommodate the peculiar properties of the scrapie agent. The most widely accepted theory today is the prion theory, which posits a 'rogue' protein as the infectious source. However, Alper could not accept that a protein 'mutation' was the agent. Firstly, her UV radiation studies did not indicate a protein agent and, secondly, isolated prions did not induce scrapie. Her own theories concerning the agent were developed in the last years of her life and suggested a more dynamic and complex story.
Tikvah Alper
23048#0
Prions are misfolded proteins which characterize several fatal neurodegenerative diseases in animals and humans. It is not known what causes the normal protein to misfold; the abnormal 3-D structure is suspected to confer infectious properties. The word "prion" derives from "proteinaceous infectious particle". Prions composed of the prion protein (PrP) are hypothesized as the cause of transmissible spongiform encephalopathies (TSEs), including scrapie in sheep, chronic wasting disease (CWD) in deer, bovine spongiform encephalopathy (BSE) in cattle (commonly known as "mad cow disease"), and Creutzfeldt-Jakob disease (CJD) in humans.
Prion
19344418#0
Bovine spongiform encephalopathy (BSE), commonly known as mad cow disease, is a neurodegenerative disease of cattle. Symptoms include abnormal behavior, trouble walking, and weight loss. Later in the course the cow becomes unable to move. The time between infection and onset of symptoms is generally four to five years. Time from onset of symptoms to death is generally weeks to months. Spread to humans is believed to result in variant Creutzfeldt–Jakob disease (vCJD). As of 2018 a total of 231 cases of vCJD have been reported globally.
BSE is due to an infection by a misfolded protein, known as a prion. Cattle are believed to have been infected by being fed meat-and-bone meal (MBM) that contained the remains of other cattle who spontaneously developed the disease or scrapie-infected sheep products. The outbreak increased throughout the United Kingdom due to the practice of feeding meat-and-bone meal to young calves of dairy cows. Cases are suspected based on symptoms and confirmed by examination of the brain. Cases are classified as classic or atypical, with the latter divided into H- and L types.
Efforts to prevent the disease in the UK include not allowing any animal older than 30 months to enter either the human food or animal feed supply. In Europe all cattle over 30 month must be tested if they will become human food. In North America tissue of concern, known as specified risk material, may not be added to animal feed or pet food. About 4.4 million cows were killed during the eradication program in the UK.
Four cases were reported globally in 2017 and the condition has been deemed to be nearly eradicated. In the United Kingdom, from 1986 to 2015, more than 184,000 cattle were diagnosed with the peak of new cases occurring in 1993. A few thousand additional cases have been reported in other regions of the world. It is believed that a few million cattle with the condition likely entered the food supply during the outbreak.
Bovine spongiform encephalopathy
11332374#26
Wheat diseases such as wheat bunt and stinking smut can be successfully treated with a fungicide. 
Disease of plants and animals can break an agricultural producer. Tuberculosis in animals was an early threat, and cattle needed to be tested, and areas accredited in 1956. The newer disease such as chronic wasting disease or transmissible spongiform encephalopathy (TSE) affects both elk and deer. Elk and deer raising is a pioneer field of domestication, has had a setback with this disease. Mad cow disease in cattle and scrapie of sheep are monitored by the Canadian Food Inspection Agency. The poultry sector was plagued by Pullorum disease, and by controlling the flock via poultry husbandry, this disease has been brought under control.
Agriculture in Saskatchewan
221689#31
The prion gene that codes for the prion protein is highly conserved in most mammals, meaning the gene is similar and present in most species of mammals. Three locations on the prion protein gene have been identified as highly polymorphic and may have an effect on scrapie: codons 136, 154, and 171. Codon 154 has not shown any evidence of having a high effect on scrapie susceptibility, but is most likely having an effect on incubation time of the disease. Codons 136 and 171 are thought to control the incubation time as well as the susceptibility of the disease, and are the ones the USDA uses in its breeding standard. Codon 171 has been determined to be the major genetic factor in scrapie susceptibility.
Scrapie
20198359#4
After the first case of mad cow disease that was discovered, two more cases emerged. In 2005, the second instance was found in a cow in Texas, and the third was found in 2006 in a cow from Alabama. In 2012, this issue still remains a controversy. On April 24, 2012, the Department of Agriculture discovered a dairy cow in central California with mad cow disease. The USDA's chief veterinary officer, John Clifford, stated that the cow's meat did not enter the food supply. In addition to this, the carcass will be destroyed. The infected cow was found due to random sampling and is considered the fourth cow in the U.S. to be infected with BSE. This has caused the controversy to arise once again and speculation on whether the VSTA regulates testing for BSE in cows is still a hot topic to be discussed.
Virus-Serum-Toxin Act
221689#28
"With scrapie, the archetypical TSE, which is a natural disease in sheep and goats, the disease can appear suddenly in a flock in the absence of any known exposure to infected flocks (Palsson, 1979). Finally, fields in Iceland, that were left empty for up to 3 years after the destruction of scrapie-infected flocks, were repopulated with known scrapie-free sheep, and some of the sheep in this latter group subsequently developed scrapie (Palsson, 1979). This last 'experiment in nature' has yielded similar results a number of times in Iceland and in the United Kingdom. In one Icelandic farm, flocks have been eradicated three times; each time, the farm was left without sheep for 2 years, and after restocking with sheep from scrapie-free areas, the disease reappeared. Several years ago, a suggestion was made (S Sigurdarson, personal communication) that hay mites would be a good candidate as a vector for scrapie; this led to infection of mice with mite samples prepared from hay obtained from five Icelandic farms. Ten of these 71 mice became sick after injection with mite preparations from three of the five farms (Wisniewski et al, 1996; Rubenstein et al, 1998). The incubation periods ranged from 340 days to 626 days, and these mice had the protease-resistant form Prp of a host-coded glycoprotein, PrP . The protease-resistant form is a marker of TSE disease (Prusiner, 1991; Parchi et al, 1996). For some of these clinically positive mice, the banding pattern on WB analysis was unique (Wisniewski et al, 1996; Rubenstein et al, 1998)."
Scrapie
221689#4
The disease has been notifiable in the EU since 1993 but unlike BSE there was no evidence as of 1999 to suggest that scrapie is a risk to human health. In July 2003, a Canadian Food Inspection Agency officer said that while scrapie shows up every year on Canadian farms, "We've had a lot of experience with scrapie and there's never been a link between scrapie and human illness." As of 2004, the USDA made no mention of scrapie in its "Sheep and Goats Death Loss" circular.
Scrapie
6884756#12
Having worked with producer Michael Wearing on both Rainy Day Women and Ashenden, Pirie's 1992 conspiracy thriller Natural Lies (BBC) became something of a return to the form of the producer's acclaimed Edge of Darkness (BBC, 1985). At the centre of the plot was the then-current subject of BSE, or 'Mad Cow Disease', spreading to humans with lethal consequences. Like Edge of Darkness, with its subject matter of nuclear waste cover-up, Natural Lies took its alarming theme and cleverly enveloped it within a thriller; resulting in a suspenseful story capable of standing up to the Hitchcock comparisons that it occasionally invited.
David Pirie
171865#6
Bovine spongiform encephalopathy (BSE), commonly known as "mad cow disease", is a fatal, neurodegenerative disease of cattle, which infects by a mechanism that surprised biologists upon its discovery in the late 20th century. In the UK, the country worst affected, 179,000 cattle were infected and 4.4 million killed as a precaution. The disease can be transmitted to human beings who eat or inhale material from infected carcasses. In humans, it is known as new variant Creutzfeldt–Jakob disease (vCJD or nvCJD), and by June 2007, it had killed 165 people in Britain, and six elsewhere with the number expected to rise because of the disease's long incubation period. Between 460,000 and 482,000 BSE-infected animals had entered the human food chain before controls on high-risk offal were introduced in 1989.
Agricultural policy