Many if not most folks dont' even realize they get it because they catch EBV as a child. In children, it generally causes no symptoms or symptoms so mild that they are dismissed as a normal childhood virus. You know, the sort you miss 2 days of school for and then go on. This is the reason most folks don't know they've had it.

When we get older - teens and adults -, we are more likely to have it develop into mono or other things that realistically make your life difficult for a while.