Something I seemed to have missed. Lockjaw. We all get the vaccination, seems like a horrible way to go. Tetanus... must be common in the soils and dirt.
https://en.wikipedia.org/wiki/TetanusI might also include a wound infection system to disable players. Maybe even animal bites will make it take forever to recover from wounds. If we expand on this 'disease' it would give good grounds to expand on a 'healer' profession to focus on cleaning up wounds and aid recovery. Then we'll need someone to share their medical expertise.
I remember in the 90's a doctor refused to address my question about wound treatments. His hippocratic oath meant that he could not encourage a youth to play a 'killing game'. Thats what we pen paper rpgers are, sick twisted people obsessed with killing.