Not sure how much to be concerned about mad cow disease in the US. The article is a little scare mongery and doesn’t seem to have an entirely accurate grasp on prions. However, it does seem like the US isn’t investigating and regulating beef to sufficiently insure it is safe of contamination from mad cow. This is par the course for regulation in general for food from what I gather. However vCJD is a bit worse than most other things one has to worry about with food these days. I think if mad cow were to become a real problem regulators would be able to control it, but it isn’t clear they’d be able to before-hand. Regardless it seems like it is another point in favor of grass-fed, non-factory farmed beef.