Great article!

A details: it's absolutely not clear that "Mad Cow Disease" is a different prion disease from kuru.

The two have very much the same symptoms and mechanism of spread. More, kuru did not exist in North America until some time after the Nobel Prize-winning doctor Daniel Gajdusek brought an extract from the brains of people who'd died of kuru and injected it into monkeys that were allowed to roam free in a nature preserve.

It's impossible to prove cause and effect, of course, but the circumstantial evidence is fairly robust. See the fascinating book "Brain Trust" by Colin Kelleher.