Poisonous Person

[Traab]

Being a walking plague carrier would mean not only would YOU be barred from entering any cities or towns, but likely your entire party just by association with you. Meaning it would be really hard to buy supplies, sell loot, get upgrades, etc. You may find yourself and your party chased by mobs of angry villagers who dont want to be poisoned by your presence. Then when you consider the combat aspects. Not only do you have to worry about your position around the mobs, but your allies as well. That sword sage cant get too close to the guy you are attacking or else he will start taking whatever damage the disease does as well.

All that being said, it sounds to me like an interesting, if complicated wrinkle to add to a game. It has some definite upsides and downsides to it, and depending on the strength of the poison, it could be balanced, though the exact specifics should be left to the DM. *EDIT* Another downside is stealth. If the plague you carry does harm to the environment as well, your party will suck at hiding due to the path of death following you wherever you go.