INDEPTH: MAD COW
Testing for mad cow
John Bowman, CBC News Online | December 29, 2003 Updated Jan. 8, 2004
The recent cases of BSE in Canada and the U.S. have brought the testing procedures for the disease in those countries into the spotlight, with some people saying the countries aren't doing enough to screen for it.
Bovine spongiform encephalopathy, commonly known as mad cow disease, is caused by the abnormal form of a protein called a prion, so tests for the disease are really tests for the presence of this infectious agent.
The test for mad cow disease must be done on samples of brain and spinal cord tissue of dead animals, where the prions are most highly concentrated. There is no approved test for live animals.
After a single case of BSE was found in an Alberta cow in May 2003, the province, which produces 70 per cent of Canada's beef, said it would spend $15 million to test up to 25,000 animals. Alberta had tested 849 cows in 2002.
QUICK FACTS
An American company, Bio-Rad, is the leading seller of test kits for mad cow disease to Europe and Japan, but the test is not approved for sale in the U.S. The company's shares reached record highs after the first U.S. case of mad cow was found.
Alberta's agriculture minister, Shirley McClellan, said Alberta would work with Ottawa to meet a national goal of testing 65,000 head of cattle every year.
Officials from the U.S. Department of Agriculture defended that country's record of testing for BSE after its first case was confirmed in late December 2003.
Ron DeHaven, the USDA's chief veterinarian, said more than 20,000 animals have been tested for BSE in the U.S. in each of the last two years. The testing is targeted to cows that exhibit symptoms of a disorder of the central nervous system. DeHaven said their testing used a large enough sample that even if mad cow were in one in a million cows, they would find it.
As well, DeHaven said USDA veterinarians always inspect "downers," cows that can't walk, for signs of nervous system disorders. Inspectors found 130 "downers" with such disorders last year and all were tested for mad cow, DeHaven said.
QUICK FACTS
Although no test for BSE that can be done on live animals has been approved, several labs around the world are competing to develop one. American, French and German labs are leading the research into a test sensitive enough to detect minute amounts of the mad cow prion in blood.
But testing 20,000 animals in a country with nearly 100 million head of cattle, 35 million of which are killed every year, pales in comparison to Japan. That country tests every one of the 1.3 million cows it slaughters each year.
The wide-scale testing came as a result of a government panel investigating the country's first case of mad cow in September 2001, which found that government officials ignored a World Health Organization warning to ban animal feed made from animal byproducts. After the investigation, Japan banned the feed and mandated BSE screening for every cow destined for human consumption.
But testing 100 per cent of the herd came at a high price for Japan. In the first two years, the country spent $65 million US on equipping 120 inspection centres with testing equipment and increasing the number of inspectors. Recalling suspected meat and destroying cattle cost millions more on top of that.
Testing all the cows slaughtered in the U.S. would be prohibitively expensive and, U.S. officials say, unnecessary.
DeHaven says BSE is a disease of old cows. It has an incubation period of between three and eight years, meaning an infected cow won't exhibit symptoms for at least three years after infection.
For this reason, the European Union tests all cattle older than 30 months for BSE. But even that doesn't guarantee that all infected cows will be found. The most recent confirmed infection in Japan, in November 2003, involved a bull that was just 21 months old.
^TOP
|
|
 |
 MENU |
|
|
| RELATED: |
|
|
| EXTERNAL LINKS: |
|
|
| MORE: |
|
|
|
CBC does not endorse and is not responsible for the content of external sites. Links will open in new window.
