The condition of a district impacted by actions of the player. Each district is monitored by a percentage gauge can be viewed in the player's inventory menu. Each district's score is based on the condition of the populace and how the player interacts with them.
If the civilians are sick or killed the score decreases and eventually the district becomes "lost" and is considered abandoned or a dead zone. Reid has the option of feeding off of citizens or not, and in that same manner, Reid can create or craft medicine to help citizens to maintain the balance.