Canada has confirmed a case of mad cow disease in a 13-year-old beef cow from Alberta, but officials say no part of the infected cow entered either the human or animal food system.

It is Canada's 11th reported case of mad cow disease, or bovine spongiform encephalopathy, since 2003.

The Canadian Food Inspection Agency has seized the animal's carcass but provided no details about where in Alberta the animal was discovered.

The food agency said the discovery should not affect Canada's status as a country where mad cow is considered a controlled risk, a desirable status Canada earned this year through the World Organization for Animal Health.

The infected animal was identified by a national monitoring program that tests cattle at Canadian farms. About 190,000 animals have been tested since 2003, when the discovery of an infected cow in Alberta caused the United States, Japan and dozens of other countries to temporarily close their borders to Canadian beef.

The food agency is conducting an investigation into this most recent case to identify the animal's herdmates at the time of birth and the ways it might have become infected.

The Canadian Cattlemen’s Association, which represents Canada's nearly 90,000 beef producers, says the discovery proves that the testing and monitoring program works. Spokeswoman Theresa Keddy said Canada, as a controlled risk country, has surveillance programs in place that actually exceed international standards.

"We do a lot of testing and we are bound to find [infected animals] and gradually we will find them and eliminate them from the herd," she told CBC News.

Cow born before 1997 feed ban

In this recent case, the infected animal was born before 1997, when Canada imposed a ban on the use of certain animal parts in animal feeds, the Canadian food agency said.

Mad cow disease, which attacks the central nervous system, is thought to be spread mainly in contaminated feed, when animals consume the meat of infected animals. It attacks an animal through hard-to-destroy protein forms called prions, which can multiply in the brain, reducing it to a spongy wreck.

The risk of transmission to humans who consume meat from infected animals remains unclear, but BSE has been linked to more than 150 human deaths worldwide, most of them in Britain.