"The three cases in Canada and the one case in the US from an imported animal are isolated incidents," said FAO animal production expert Andrew Speedy. "These cases were detected because of the testing procedures that are now in place."

In the last 10 years 148 people have died of the human version of Bovine Spongiform Encephalopathy (BSE), variant Creutzfeldt-Jakob Disease (vCJD), almost all in Britain.

Last week, Japan announced its first vCJD death and suggested that the man, who died in December, had contracted the disease during a month-long stay in Britain in 1989.

The confirmation at the end of January that a goat slaughtered in 2002 had BSE was the first time the disease had been found in a species other than cows.

Before then, scientists believed goats and sheep were only affected by scrapie, a disease indistinguishable from BSE but one that can not be passed on to humans.

The FAO said the BSE-infected goat was "one example in millions" and pointed out that it was born before Europe imposed a total ban on feeding of meat and bonemeal to livestock in January 2001.

As BSE cannot be detected in young cattle, testing all meat at the slaughterhouse is not an option in combating the disease, and the FAO urged all countries to step up controls on animal feed that can spread the infection.

All countries to eliminate so-called specified risk materials -- such as brains and spinal cords -- from the food chain and ensure that if meat and bonemeal is used in feed for pigs or poultry that it be handled separately from cattle feed lines, it said.