Does Divine Health prevent the rotting disease that you contract from a wyrm’s fetid breath?
IANAA, but I’d say yes.
Paladins “are completely immune to the ravages of disease, including magical diseases. …[including] foes such as mummies or werewolves…”
Fetid Gas is “a noxious rotting disease” ended by Cure Disease.
Seems pretty clear cut to me.
In general, I assume ACKS is written in a more common-sense and conversational tone than the legalistic one of 3.5 and 4e D&D. So, disease = disease. I wouldn’t get twisted up trying to find reasons to construe it otherwise.
Yes, it prevents all disease.
Personally I was always annoyed by the fact that in earlier editions of D&D, paladins were immune to all disease…except every disease they’d actually encounter in actual play.