Either we are, and the effects are too slow-moving to be statistically noticeable, or prions just aren’t that good at spreading themselves, or both. In any case, the empirical evidence is that they’re not actually very good at plaguing.
Which makes sense, when you think of the enormous amount of R&D that viruses have put into this, and prions come along and expect to become a plague with no armor, no capacity to evolve, and no mass replication strategy. It’s actually quite disrespectful.
