The scariest part for me is: it can just form randomly in one's body, and there's no way to tell until it's too late.

The really scary part is that there's no real testing in our food supply. Wild animals can also spread it over crops and it can stay present in soil for years. If it makes the jump to humans, were screwed. That or dental tools (they may not get sterilized to the point of destroying prions) will be what gets us.