It is not surprising that the U.S. has mad cow disease given our flaunting of World Health Organization recommendations.<1> What is surprising, however, is that we actually found a case given the inadequacy of our surveillance program...
First, American do eat bovine central nervous system tissue...
Except for Islamic halal and Jewish kosher slaughter (which involve slitting the cow's throat while the animal is still conscious), cattle slaughtered in the United States are first stunned unconscious with an impact to the head before being bled to death. Medical science has known for over 60 years that people suffering head trauma can end up with bits of brain embolized into their bloodstream; so Texas A&M researchers wondered if fragments of brain could be found within the bodies of cattle stunned for slaughter. They checked and reportedly exclaimed, "Oh, boy did we find it."<24> They even found a 14 cm piece of brain in one cow's lung....
http://organicconsumers.org/madcow/Greger122403.cfm