2 years ago wasn't mad cow disease in Europe... it was hoof and mouth disease, a disease that spreads and kills much more quickly...
Also, the incubation period for mad cow disease is 7 to 8 years...
The majority of cattle are slaughtered well before that... Thus, the odds of seeing symptomatic cattle in the U.S. is relatively low.
The last time I checked (a couple of years ago), the United States tested as many cattle in a year as Europe tests in a week. I don't know if the tests are independently performed or not. If not, then I have serious doubts as to whether anyone would be very forthright, considering the economic ramifications. According to the article, 20,526 cattle were tested last year... Out of how many?
The cattle lobby is very strong in some states... Last year (or was it the year before), they forced an entire herd of sheep in Vermont to be destroyed due to a risk of "mad cow disease". Nonetheless, that breed of sheep had never been known anywhere to even be a carrier for any variants of the disease. But, that breed of sheep was well known as a milk producer and posed a slight risk to the dairy industry as an alternate source of milk. Just ONE cow ever found in Canada with mad cow disease and all imports of beef from Canada are stopped - does that sound like reasonable risk assessment to anyone? Or over-reaction that benefits only the beef industry?
And, lastly for your consideration, the hamburger you're eating at many of the fast food chains (at least McD's) did not come from just one cow... In order to keep as consistent of a product as possible (ever notice any variation in taste between burgers?) the meat of numerous cattle is mixed together, and flavorings added to keep the taste the same. Thus, by eating one of those burgers, you have a far higher chance of getting something that was contaminated. Or, look at it this way... when there's a salmonella problem, etc., ever notice that the impact is far more than what would be produced by one or two or ten cows?
Just some food for thought... I still eat McD's burgers from time to time, but would rather eat stuff from the local butcher shop.