What I did with Applied Combustinetics was make it so that players who used the abilities more frequently became increasingly (by a long duration stacking debuff) vulnerable to fire and blasting damage(Fire Hazard). The same could be done here. The more the plague victim abilities are used, the stronger the plague's hold on the player is and the more vulnerable they are to fire. It forces players to choose between a staple ability, or not being murdered by a trap/fire damage source.
I would love to dive into making this, but right now DoD has taken a backseat in my gaming allotment, so it isn't likely to happen soon if it does happen. I appreciate the input and feedback on the idea though!