Ham off the bone is the same risk as any other deli meat.

I wouldn't eat it (unless it was hot, say on pizza).

The risk of listeria is pretty small but it does still happen. Remember that you usually don't get any symptoms (and if you do they are usually cold like, not gastro like) so you probably wouldn't know if you had it. It can stay in your body a long time (I think 70 days) so it can create a problem for you well after you ingested it.

My baby spent 5 days in special care due to an unknown infection that set in soon after birth. Probably would've been something he was exposed to during the birth. I cannot tell you how stressful those 5 days were. You can never be too careful as far as I'm concerned.