- Also called:
- mad cow disease
bovine spongiform encephalopathy
-
What is bovine spongiform encephalopathy (BSE)?
Bovine spongiform encephalopathy (BSE), also known as mad cow disease, is a fatal neurodegenerative disease in cattle. BSE is caused by an unusual infectious agent called a prion. The prion is an altered form of a normally harmless protein in the brain. As the prions multiply, they accumulate in nerve cells, causing damage and the characteristic neurodegeneration. Brain tissue from infected organisms becomes pitted with holes, resulting in a sponge-like pattern.
Signs of BSE include behavioral changes like agitation and nervousness, progressive loss of muscular coordination, and loss of locomotive function. Infected animals may lose weight, show muscular contractions, walk abnormally, and isolate themselves. Death typically occurs within a year of the onset of symptoms, and there is no known treatment.
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What causes BSE in cattle?
Bovine spongiform encephalopathy (BSE), also known as mad cow disease, is a fatal neurodegenerative disease in cattle. It is categorized as a transmissible spongiform encephalopathy because it causes the brain tissue to become pitted with holes in a spongelike pattern.
BSE is caused by an unusual infectious agent called a prion. Prions are modified forms of a normally harmless protein found in the brain. In its aberrant form, the prion protein multiplies and builds up in nerve cells, which damages the cells and leads to neurodegeneration. It is thought that BSE arose when cattle were fed high-protein supplements made from ruminant carcasses.
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What is meant by the 'spongiform' part of BSE?
Bovine spongiform encephalopathy (BSE) is a fatal neurodegenerative disease in cattle that belongs to a group of diseases called transmissible spongiform encephalopathies. The term "spongiform" refers to the sponge-like pattern of holes that develop in the brain tissue of affected organisms. This characteristic pitting is caused by the accumulation of prions, which are infectious agents, in nerve cells, leading to neurodegeneration and the manifestation of neurological symptoms.
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How does BSE affect a cow's brain and nervous system?
Bovine spongiform encephalopathy (BSE), also known as mad cow disease, is a fatal neurodegenerative disease in cattle that affects the nervous system.
BSE is caused by prions, infectious agents that accumulate in nerve cells, causing damage and neurodegeneration. The brain tissue of infected animals becomes pitted with holes, resulting in a sponge-like appearance. Signs of BSE include behavioral changes such as agitation and nervousness, progressive loss of muscular coordination, and locomotive dysfunction. In advanced stages, the animal may lose weight and isolate itself from the herd. Death usually follows within a year of the onset of symptoms.
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What are the main symptoms of BSE in cattle?
Bovine spongiform encephalopathy (BSE), also known as mad cow disease, is a fatal neurodegenerative disease in cattle. The symptoms of BSE include behavioral changes such as agitation and nervousness, progressive loss of muscular coordination, and loss of locomotive function. In advanced stages, the animal may lose weight, show muscular contractions, walk abnormally, and isolate itself from the herd. Death usually occurs within a year of the onset of these symptoms.
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How is BSE diagnosed and what changes are seen in the brain tissue of affected cows?
Bovine spongiform encephalopathy (BSE), also known as mad cow disease, is diagnosed through observation of its clinical signs and laboratory testing of brain tissue. Symptoms include behavioral changes like agitation and nervousness, progressive loss of muscular coordination, weight loss, and isolation from the herd.
Postmortem examination reveals the characteristic spongiform changes in the brain, where the tissue becomes pitted with holes, resembling a sponge. This is due to the accumulation of prions, infectious agents that are modified forms of a normal protein, which damage nerve cells and lead to neurodegeneration. An atypical strain of BSE exists that lacks these holes.
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bovine spongiform encephalopathy (BSE), a fatal neurodegenerative disease of cattle.
Bovine spongiform encephalopathy is caused by an infectious agent that has a long incubation period, between two and five years. Signs of the disease include behavioral changes, such as agitation and nervousness, and a progressive loss of muscular coordination and locomotive function. In advanced stages the animal frequently loses weight, shows fine muscular contractions over its neck and body, walks in an abnormal and exaggerated manner, and may isolate itself from the herd. Death usually follows within a year of the onset of symptoms. No treatment or palliative measures are known.
First recognized in cattle in the United Kingdom in 1986, BSE became epidemic there, particularly in southern England. Cases also were reported in other parts of Europe and in Canada. The disease is similar to the neurodegenerative disease of sheep called scrapie. It is thought to have arisen when cattle were fed high-protein supplements made from ruminant carcasses and offal (the trimmings of butchered animals). Although animal remains had been used as a source of dietary supplements for several decades without problems, modifications to the rendering process—specifically, reduction in the temperatures used and discontinuance of certain solvents—in the early 1980s were followed by the outbreak of BSE. The timing of events suggested that the modified process no longer incapacitated the infectious agent. In 1988, on the basis of this inferred connection, the British government banned the use of animal-derived protein supplements. The following year the U.S. Department of Agriculture banned the import of live ruminants from countries known to have BSE, and in 1997 both the United States and Canada implemented bans on the use of animal-derived proteins in ruminant feed. From 1986 to 2008 nearly 185,000 cases of BSE were confirmed in the United Kingdom. In contrast, through February 2008 a total of just 16 cases of BSE were confirmed in North America, with the majority of cases occurring in Canadian-born cattle. Because of heightened awareness of increasing prevalence of BSE in Canadian cattle, Canada enhanced its feed ban in 2007 to prohibit the inclusion of “specified risk materials,” as well as animal proteins, from all animal feeds.
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BSE, scrapie, and similar diseases in other species, such as Creutzfeldt-Jakob disease and kuru in humans, are categorized as transmissible spongiform encephalopathies. They are so named because the brain tissue of organisms with the disease becomes pitted with holes in a spongelike pattern. The cause of these diseases is attributed to an unusual infectious agent called a prion. The prion is a modified form of a normally harmless protein found in the brain of mammals and birds. In its aberrant form, however, the prion protein builds up in nerve cells as it multiplies. This accumulation somehow damages these cells and leads to the characteristic neurodegeneration. It is suspected that there also exists an atypical strain of BSE, which arises spontaneously (as opposed to orally through the ingestion of contaminated feed) and leads to a distinct prion disease characterized by a lack of pitted holes in the brain.
After the emergence of BSE, concern grew over a possible relationship between the animal disease and the occurrence of Creutzfeldt-Jakob disease in people. Beginning in the mid-1990s a new variant form of Creutzfeldt-Jakob disease (nvCJD) took the lives of dozens of people in Europe. In experiments with mice, researchers found that prions from human cases of nvCJD caused a disease pattern similar to that caused by prions from cows with BSE. The result suggested that the human infection is linked to BSE.