Canada confirmed on Tuesday its sixth case of mad cow disease and said it would investigate where the cow was born and what other animals may have eaten the same feed.
The Canadian Food Inspection Agency says test results confirmed what was suspected last week. The animal was at least 15 years of age, and was born before Canada implemented restrictions on potentially dangerous feed in 1997.
The agency said it was launching an investigation.
Mad cow disease is believed to spread through feed, when cows eat the contaminated tissue of other cattle. Humans can get a related disease, variant Creutzfeldt-Jakob Disease, in similar fashion — by eating meat contaminated with mad cow. There have been more than 150 human deaths worldwide linked to the variant.
Two of the six confirmed mad cow cases in Canada have involved animals that were infected after 1997, when a ban was instituted on the use of cattle parts in feed destined for cattle, or other ruminants such as sheep and goats.
The agency says Canada’s food supply is safe, and the level of mad cow disease in the national cattle herd is very low. Canada has an estimated national herd of 17 million cattle.
Shipments of live cattle to the United States were halted in 2003 after the first reported mad cow case in Canada. Trade in young animals resumed last year, but there has been no word on when the border may be reopened to older animals.
U.S. Agriculture Department spokesman Ed Loyd said last week trade was resumed with Canada with the assumption that more cases of BSE would be found. Loyd said U.S. officials have “a high level of confidence in the safeguards and mitigating measures in place in the U.S. and Canada.”