Unfortunately even once you are hired it can become a sticky situation if you need accomodations down the line. Of course no one is going to say you weren't hired or were fired because of MS but imvho it still happens. The other thing is that as someone pointed out we aren't disabled unless we are disabled so to the best of my knowledge just having MS doesn't equal disability.

I only disclosed during my employment physical, after getting the job offer in writing because I was going on their health insurance plan. If they followed HIPAA no one other than HR and the employee health office should know. I have no plans to tell anyone else on my job unless it becomes an issue.