The investigation into the recent finding of the first U.S. dairy cow infected with �mad cow disease�, unearthed the fact that the cow came from Canada two years ago.  

The U.S. Agriculture Department's chief veterinarian, Ron DeHaven, said that according to records provided by Canadian officials the infected cow was among a herd of 74 that was imported into the U.S. from Alberta, Canada, in 2001.

There was a case of mad cow reported in Alberta back in May. The U.S. agriculture department said that meat linked to the infected cow was sold in four western U.S. states - California, Nevada, Oregon, and Washington. 

As a result of the discovery of the infected cow, more than a dozen countries have banned American beef. These include Argentina, Australia, Brazil, Cambodia, Canada, Chile, China, Colombia, Costa Rica, Egypt, Hong Kong, Indonesia, Jamaica, Japan, Kuwait, Malaysia, Mexico, Nicaragua, Peru, Russia, Singapore, South Africa, South Korea, Taiwan, Thailand, Uruguay, Venezuela, and Vietnam.

The scare comes from the fact that the human variant of the disease has been linked to beef from infected cattle. The illness that affects humans, Creutzfeldt-Jakob disease, has killed more than 100 people worldwide since 1986 when it was discovered in the U.K. Scientist have determined that humans contract the disease by eating beef that contains brain and spinal cord tissue from infected cows.

The U.S. beef ranchers are already feeling the sting from the discovery of the infected cow. According to some reports the U.S. beef industry has already lost 90 % of its export market in the three days since it was confirmed that the infected cow discovered in Washington did indeed have mad cow disease. 

At home, beef prices are expected to drop as a result of the scare. 

The herd and offspring of the infected cow have been quarantined by U.S. health officials.