Bovine Spongioform Encephalopathy ( also known as BSE or "mad cow disease") is a progressive degenerative disease that affects to central nervous system of cattle. It belongs to a group of similar but distinct neurological diseases that include scrapie in sheep and Creutzfeldt-Jacob disease (CJD) in humans. The cause of BSE is unknown and there is no treatment for this fatal disease.
BSE does not exist in Canada. Since 1986, when first diagnosed in Great Britain, BSE has profoundly affected the British cattle and beef industries. BSE has been confirmed in domestic cattle in Ireland, France, Portugal, and Switzerland, and in cattle exported from Great Britain to Oman, the Falkland Islands, germany, denmark, and Italy.
Canada has experienced one case of the disease in a cow imported from Great Britain in 1987, and diagnosed with BSE six years later. The federal government immediately took extraordinary measures to deal with risks BSE might pose to other cattle in Canada. These measures included:
BSE-affected animals may display symptoms such as:
When first noticed, clinical signs may resemble those of rabies. Rabies progresses rapidly over a few days. Incomparison, the symptoms of BSE progress over a period of two to six months. Typically, it takes from three to six years from the time of infection for the clinical signs of BSE to appear.
Great Britain's current epidemic is belived to have been caused by the inadvertent feeding to cattle of meat and bone meal supplements that were contaminated with an infectious agent. This occurred in the late 1970s and early 1980s. Once cattle became infected, the BSE agent was recycled in the cattle food chain through the feeding of rendered material from slaughtered animals to other cattle. This increased the magnitude of the epidemic.
Great Britain banned the feeding of ruminant derived protein (from sheep and cattle) to ruminants in 1988. the use of potentially contaminated bovine tissue was prohibited in the manufacture of all animal feed. this ban has had an effect, as the number of BSE cases has declined since the winter of 1992-93.
Diagnosis of BSE is based on clinical signs of the live animal followed by the appearance of characteristic lesions in a post-mortem microscopic examination of the bran. There are no tests for the disease in live animals.
Canada meets of exceeds international requirements to prevent the entry of BSE from other countries. The entry of live ruminants, bone or meat meal from any country considered to be BSE-infected is prohibited. BSE has been a reportable disease in Canada since 1990, and Agriculture and Agri-Food Canada (AAFC) as implemented a BSE surveillance program. In addition, no slaughter facility in Great Britain has been approved by AAFC for export of beef to Canada.
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Other Links:
Bovine Spongiform
Encephalopathy (BSE) - Commonwealth Agriculture Bureau International
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Surveillance: Special Issue - Exotic Diseases, Vol 23,
1996
MAF Regulatory Authority, Ministry of Agriculture
P.O. Box 2526, Wellington, New Zealand
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Ministry of Agriculture, Fisheries and Food, United Kingdom ISSN:0269 5545
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