If just one infected cow entered the US it could potentially infect 45,000 other cows, according to a Consumers Union biologist.

"This latest case of mad cow disease in Canada points to a significant North American mad cow problem," says Michael Hansen, a biologist with Consumers Union specializing in food safety. This latest positive cow, reported to be six years old, was born after FDA's and Canada's current feed restrictions went into effect, indicating that the restrictions are not strong enough to prevent the spread of this brain-wasting disease.

Extreme Vigilance Is Called For

Consumers Union, in comments submitted to FDA in December, noted that new research conducted in the United Kingdom shows that miniscule amounts of infected cattle material can, if fed to other cattle, transmit mad cow disease.

"Based on this new research, if just one infected cow entered the US feed supply and the brain and spinal cord of that animal were maximally dispersed in feed, it could potentially infect 45,000 other cows," Hansen says. "That's why we have to be extremely vigilant about keeping any infected animal material out of feed and food."

FDA recently proposed prohibiting brains and spinal cords of cattle over 30 months in animal feed. Consumers Union recommends keeping all mammalian material out of animal feed, as has been done in the UK, but urges that at least brains and spinal cords, and other risky materials such as intestines known as "specified risk material" from cattle over 12 months, be prohibited.

In addition, it urges FDA to close three loopholes -- for cattle blood, restaurant wastes, and chicken coop floor wastes -- as it promised to do two years ago.

'We Must Increase Surveillance'

The US Department of Agriculture (USDA) opened the border between the United States and Canada last summer, after a two-year closure, for all cattle under 30 months. Animals under 30 months seldom exhibit symptoms of mad cow disease, but can still incubate it.

Mad cow disease is believed to be transmitted through eating infected material. When Canadian cattle are slaughtered in the United States, they are processed like US cows into meat for human consumption, as well as into pig, chicken and pet food.

"We must also increase the USDA surveillance program, which is testing just one percent of all animals slaughtered in the United States," Hansen said. "We think USDA should be testing all animals over 20 months at slaughter. But at a minimum, USDA should test all high-risk cattle, and all cattle from Western Canada, from the Pacific Northwest and from Texas, where cases have been identified."