Why is talk of Mad Cow Disease avoided in America?

What about prion cross-contamination due to municipal sewage being used as fertilizers in factory farms? The Organic Consumers Association has relevant news/topics but mainstream media doesn't cover it.
The cattle industry is protected by corrupt people in high places.
When a mainstream reporter investigates this sort of thing, they run into a wall of officials who know how to lie, hide evidence and falsify documents.

And, of course, you also have media outlets such as FOX news who are actually willing to participate in covering up such things:
http://www.talkmydisease.com/