Prion disease has long been a favorite amongst the community. Unfortunately, in it's current state, the negative effects of the disease itself (loss of food and water values) happens far too quickly and doesn't permit players to live long enough produce a fearful effect on those they come into contact with (laughing, twitching, etc.) for a significant duration.
Balancing this out to where the effects do take a toll on food and water, but not at such a rapid rate, perhaps where a player who has obtained the disease can sustain a life for a few hours as opposed to it's current state being anywhere from 30-60 minutes max.
That way we can plague other survivors with the fear of giggles and cannabalism once again without dying off prior to those highly desired effects of laughter and twitching ever take effect.
Thanks