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Mad Cow Disease, or bovine spongiform encephalopathy (BSE), is an illness that affects the central nervous system of cattle. It is part of a family of diseases known as transmissible spongiform encephalopathies (TSEs). All TSEs are believed to be linked to an abnormal form of a protein known as a prion. Accumulation of this abnormal protein leads to a sponge-like appearance of the affected brain and causes neurological illness and eventual death. The time between an animal’s exposure to the disease and the onset of symptoms normally ranges from four to five years.  Two to six months after the onset of symptoms, the animal dies. Diagnosis of BSE is not possible in live animals and can only be done by examining the brain after death.

BSE in the United Kingdom

Cases in cattle were first reported in the United Kingdom (UK) in 1986. Scientists believe that the BSE epidemic in the UK was caused by feeding cattle infected meat and bone meal The practice of feeding rendered material (animal tissue converted into a product) from slaughtered cattle to live cattle magnified the problem. In 1988, the UK banned the use of rendered material in animal feed, thus removing potentially contaminated material from the food chain.

BSE in Canada

Canada banned the import of European beef in the early 1990’s and has since restricted the importation of beef and beef products from any country that is not designated as BSE-free. Canada has an active surveillance program in which the brains of all cattle that may potentially have BSE are tested for the disease. BSE has been a reportable disease in Canada since 1990, meaning that any suspect case of BSE must be reported to a federal veterinarian.

The first case of BSE in Canada occurred in 1993 in a beef cow imported from Britain in 1987. The entire herd and any other potentially infected cattle were destroyed.

In 1997, the Canadian Food Inspection Agency (CFIA) issued a feed ban to minimize the risk of transmitting BSE in Canadian cattle by excluding specified risk materials (SRMs). SRMs are ruminant tissues most likely to contain the BSE-causing agent (i.e. brains and spinal cords). The feed ban was expanded in 2007 to prohibit SRMs from being used in all animal feed, pet foods and fertilizer.

On May 20, 2003, Canadian officials reported that a single case of BSE had been confirmed in Alberta; the slaughtered cow did not enter the food chain. Canada implemented an enhanced BSE surveillance program following the case of BSE in 2003. The program is in agreement with the guidelines recommended by the World Organization for Animal Health (historically and currently known as OIE) and sets targets for increased testing for BSE. The objectives are to monitor levels of BSE in Canada, and to check the effectiveness of the measures in place.

The OIE classifies countries according to perceived risk of BSE, where there are three categories: negligible, controlled and undetermined risk. According to OIE, Canada is classified as a controlled-risk country; as its BSE safeguards comply with OIE recommendations though new BSE cases continue to emerge. As of November 2008, 13 cases of BSE in Canada have been confirmed by the CFIA.

Creutzfeldt-Jacob disease

A human form of TSE, first diagnosed in the 1920s, is named Creutzfeldt-Jacob disease (CJD) after the two German scientists who first described the illness. Classical CJD (cCJD) is unrelated to the consumption of beef and occurs naturally in the population at a rate of around one person per million per year, making it extremely rare. On average, thirty Canadians of around age 60, are diagnosed with cCJD each year. There is no known cure.

In the early 1990s, British researchers noted a new illness having many of the classical CJD symptoms, but with several unique characteristics. Most notably, the emerging illness affected people in their late 20s. In 1996, researchers confirmed a new variant of CJD, now called vCJD. The cause of vCJD was linked to the consumption of beef and beef products from cattle infected with BSE.

In the summer of 2002, the first Canadian case of vCJD was reported in a male resident of Saskatchewan. The disease was likely acquired in the UK, where the patient lived and visited during the 1980s and 1990s when BSE was widespread in UK cattle.

Information Sources

Canadian Cattlemen's Association/Beef Information Centre. (2008). Safeguards. Retrieved from http://www.bseinfo.ca/english/safeguards/default.asp

Canadian Food Inspection Agency. (2008). Bovine spongiform encephalopathy (BSE) in North America. Retrieved from http://www.inspection.gc.ca/english/anima/heasan/disemala/bseesb/bseesbindexe.shtml

CBC News. (2006, October 23). Timeline of BSE in Canada and the U.S. Retrieved from http://www.cbc.ca/news/background/madcow/timeline.html

World Health Organization. (2002). Understanding the BSE threat. Retrieved from http://www.who.int/csr/resources/publications/bse/en/BSEthreat.pdf