Just a thought but could plague be used as a work around? I'm not sure if it is dependant on the general, or if it is a trait held by soldiers in an infected army, but if the latter it could be considered as a desertion rate, rather than death by plague. Generals with doctors and the such heal from plague faster, but if such traits also effect the severity of plagues (i.e. the number of units lost per turn) then the plague effects could be used as a supply/morale indicator instead of illness. Lots of ifs in that situation thought.