From meat to men: The dark green areas are countries with confirmed human cases of vCJD. Light green shows countries which have reported cases of only BSE Graphic: Zntrip/Wikipedia

A recent case of BSE in Canada has been officially linked to infected feed.

A six-year-old dairy cow from the province of Alberta, confirmed as the 12^th to be suffering from the disease, was identified in February 2008. A 13^th case has been discovered subsequently.

An investigation by the Canadian Food Inspection Agency (CFIA) found that it was "reasonable to presume that this animal was exposed to feed containing a low level of infectivity during its first year of life," it said in a statement. "The detection of this case does not change any of Canada's BSE risk parameters. The location and age of the animal are consistent with previous cases, and the BSE surveillance results to date, including this new case, reflect an extremely low level of BSE in Canada," the CFIA added.

Canada introduced a ban on animal proteins in 1997, but diagnosed its first case in 2003. The CFIA tightened up the feed rules still further in 2007 in a move to eliminate the disease in the country within ten years. However, it concedes that "a handful of new cases" will appear in future years.

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