Canada's has confirmed it's third case of bovine spongiform encephalopathy (BSE), including the find that was traced back to Canada originally found in Washington state.
The Alberta dairy cow was born in 1996, prior to the introduction of the 1997 feed ban. It is suspected that the animal became infected by contaminated feed before the feed ban.
Efforts are now underway to identify any other animals of similar risk. Specifically, the Canadian Food Inspection Agency (CFIA) is focusing on two categories of animals: recently born offspring of the infected animal and cattle born on the same farm within a year of the infected animal. This work is proceeding as quickly as possible.
The (CFIA) has also launched a feed investigation to examine what the infected animal was fed early in its life, when infection was most likely to have occurred prior to the 1997 feed ban. Given the age of the animal, it may not be possible to definitively identify a particular feed source as the origin of infection. However, information gathered through investigations and analyses continues to suggest that the feed ban has limited the spread of BSE since its implementation.
In 1989, Canada banned further importation of cattle from the United Kingdom and traced all imported cattle to their Canadian farms of origin, where they were monitored and eventually destroyed. Before this time, when BSE had not emerged as a significant animal health threat, it is likely that some imported animals entered the North American feed system.
The USDA has said that the United States would not alter the implementation of its rule to resume trade with Canada.