There was quite a hype over Mad Cow disease a few years ago, and a great many people were afraid to eat beef. Was this justified? Here are some interesting stats:

Mad Cow (vCJD) and Creutzfeldt-Jakob (CJD) are both caused by misfolding an aggregation of the same protein -- in other words, they are basically the same disease. The difference is the CJD occurs when a protein in the body misfolds spontaneously, whereas Mad Cow occurs because an ingested misfolded protein from a sick cow induces a protein the body to midfold. On the surface, then, Mad Cow sounds pretty scary. But let's look at the numbers (these are from the UK which had the worst Mad Cow "outbreak"):

~1 in 1 million people will get spontaneous CJD
in Brittain, from 1990 - 2009, there were 15 times more spontaneous CJD cases than Mad Cow cases.
So the rate of Mad Cow was, in the end, ~1 in 15 million people. If odds of 1 in 15 million scares you, maybe you shouldn't leave your house?

Yes, we need to take precautions to keep Mad Cow beef out of the food supply -- at it's worst, in 2000, 28 Brits were diagnosed with Mad Cow disease, about half as many as got CJD that year -- but we shouldn't be crippling the beef industry and spending excessive amounts of money that could be better spent elsewhere.

Reference: http://www.cjd.ed.ac.uk/