You can have mono and not know it.

I knew when I had mono, there was no ignoring it. Sickest I've ever been in my life.

I also had shingles around the same time as the mono. I've been wondering if the mono and the shingles conspired together to give me the MS. I do think there is a genetic component to it. One of my dad's 2nd cousins has MS. (she got it the same week her brother became a quadraplegic while diving into a lake. She was paralyzed for awhile same as her brother. At least she recovered from hers for the most part from what I've been told. Too bad her brother couldnt too)