And it makes them incredibly hard to fight. We basically have two ways of dealing with them:

• Use vaccination to train the host's immune system deal with it, should it ever encounter the full version.

• Use special drugs to slow down their replication to let the host's immune system deal with the rest.

Prions have no special, prion-only replication strategy we can target, and I'm not sure whether the immune system can be trained to attack only prions and not their regular protein equivalents.