Mad Cow: The Science and the Story
Amy Foulkes, CBC News Online | Updated: May 20, 2003

Should Canada Worry?

Canada has been virtually free of BSE, bovine spongiform encephalopathy, also known as Mad Cow Disease. But in May 2003, veterinary officials in Alberta confirmed that a sick cow sent to a slaughterhouse in January was inspected, found to be substandard, and removed so that it would not end up as food for humans or other animals. The carcass was, however, sent to a processing plant for rendering into oils. Its head was kept for testing. Samples were sent to the world testing laboratories in the U.K., which confirmed the case.

"What is important is that the system worked," says Alberta's agriculture minister, Shirley McLellan. "We have a very thorough and respected inspection system." She was insistent to remind the public that the disease is not contagious within a herd.

Previously, Canada had only one case of a cow infected with BSE. The animal, reported on a farm near Red Deer, Alta., in December of 1993, was imported from Britain. Agriculture Canada opted to destroy the animal and its five herd mates.

QUICK FACTS

Canada has close to 13.5 million cows and calves. About 5.7 million (or 42 per cent) are in Alberta. Canada's total beef exports amount to $2.2 billion annually, and have risen sharply in recent years. Since 1991, beef exports have risen from 100,000 tonnes to about 500,000 tonnes. Growth in exports has been greatest to Japan, South Korea and Mexico. Alberta's share of total beef exports is 39 per cent (worth about $860 million a year).

Mexico, one of the largest importers of Canadian beef at the time, temporarily banned imports of Canadian cattle after the incident. The United States, another major consumer of Canadian beef, sent observers to Canada to see how the incident was handled.

As a result, and because of the rumours of possible human health implications circulating in Britain, the Ministry of Agriculture decided to destroy any animal imported from Britain between 1982 and 1990, the year a ban was placed on British beef imports to Canada. This slaughter also included the offspring of any of those animals.

All told, 363 animals were destroyed and their owners compensated. Some said the destruction was unnecessary, especially the farmers whose cattle were killed, but the ministry said it was better to err on the side of caution after seeing what was happening in Britain.

During the summer of 1995, the disease surfaced again. The Canadian Red Cross Society revealed two of its donors had died of Creutzfeldt-Jakob disease, CJD. Two years later, concern over blood was raised again after a man was found to be a carrier of a gene linked to a hereditary form of CJD.

In August 2002, doctors confirmed a man in Saskatchewan died from new variant CJD – the human counterpart to mad cow disease. He had spent some time in the United Kingdom and it appeared he acquired the disease while he was there, doctors said.

The man had an endoscopic examination before he died and that equipment was then used on other patients. However, because of disinfection and cleaning procedures, the risk of cross contamination is minute. Public health officials phoned patients who had received examinations with the endoscope to inform them.

It's still not known if the disease can be transmitted through blood products.

In 1996, the Canadian government suspended imports of British beef embryos and semen. Agriculture Canada also began a review of the practice of using meat meal and bone meal as a protein source in beef cattle feed. In 1997, changes designed to keep animal parts out of animal feeds were implemented.

Canada also doesn't import meat or bone meal from nations where cows have been found to have BSE.

In spite of Canadian officials' confidence, a European Commission report released in 2000 placed Canada in the second rank of risk for mad cow disease. A top rank designates almost no risk.

The report cited the fact that, before 1992, mammalian meat and bone meal were routinely fed to cattle. It also noted that material containing nerve endings was rendered at temperatures too low to kill off the agent of mad cow disease, and was still used for feed.

For these reasons, the report concluded a small element of risk is still present for Canada's cattle. The Canadian Food Inspection Agency says it will make an appeal to the EC's scientific steering committee, asking for a better designation.

http://www.cbc.ca/news/indepth/background/madcow.html