A portmanteau word is similar to a contraction, but contractions are formed from words that would otherwise appear together in sequence, such as do and not to make don't, whereas a portmanteau is formed by combining two or more existing words that all relate to a single concept.
https://en.wikipedia.org/wiki/Portmanteau
"Motel" and "fog" are portmanteaus, because you wouldn't put "motor hotel" or "smoke fog" in sentences that accept the accretions, whereas you could swap "prion" for "protein infection".
"Motel" and "fog" are portmanteaus, because you
wouldn't put "motor hotel" or "smoke fog"
"Motel" and "smog" are portmanteaus, because you
wouldn't put "motor hotel" or "smoke fog"(Aside from actual domain experts in this thread saying it is an infection, that is).
Is the difference between an infection and poisoning replication?
Whether they self-replicate or not is sort of a semantic issue. They replicate in the same way "fallen-down dominos" replicate.
Prior to being a prion, they are an already complex protein, but by folding a particular way, they become a prion, which causes other proteins of the same type to fold similarly.
Infectious disease is also called transmissible diseases. Infectious microorganism or agent can be a virus, bacterium, protozoan, prion, viroid, or fungus.
https://en.wikipedia.org/wiki/Prion#Prion_replication
There is a complex dependence on forming fibres that makes them slow (long lead time to symptoms) and then fast (dead soon after getting sick).