I've been sending out the never-healing-wound guys into battle because I figured there wasn't much chance of that healing anyway, and they've been killed repeatedly without their affliction disappearing.
I've got more cripples that I'm not using to attack (AP=2 is lame). I thought they would have healed by now. Maybe my miasma is interfering: they could be auto-healing the disease they occasionally get first, and never get around to healing their legs. I wasn't really paying attention to their diseased status, but I think I saw it pop up occasionally.
Lch has disease healing first in his afflictions recovery summary:
http://forum.shrapnelgames.com/showpost.php?p=674202