Ghoul fever

Ghoul fever was a rotting disease that could kill and transform an infected individual into a ghoul.

Acquisition
Ghoul fever was contracted from the bites of ghouls, including ghasts and lacedons.

Effects
After an incubation period of about one day, an afflicted individual began showing symptoms of ghoul fever, notably in the form of a steady day-by-day decline in their stamina and dexterity as the body began to rot. If allowed to progress to its end stages, ghoul fever was not only fatal, but any creature who died from it would rise as a murderous ghoul that same night at midnight. More powerful individuals were know to rise as ghasts.

Treatment
With luck, a healthy individual could fight off ghoul fever, with the caveat that more powerful ghouls were said to inflict significantly more aggressive forms of the fever. Unlike mundane diseases, overcoming ghoul fever required a strong sense of self.