Recently 1 cow was found to have BSE.
The reaction of officialdom is the usual "move along, nothing to see, these are not the droids you are looking for". A nice everything is fine.
Here is another viewpoint:Why You Should Be Worried About the California Mad Cow Case
From the numbers we see less than 0.1% of the cows which die are tested (~40K). With this I would estimate that at least 1,000 cows with BSE and are entering the food system (chicken feed, pet food, and possibly human). Of course more testing would help with understanding the magnitude, but that is unlikely.
Food for thought....