DH was in college from 96-2000, I have been in college since 99 (at grad level now). Between the two of us and all these years, we have only known TWO people who have gotten it: my DH's roommate. But he got it from getting drunk, doing who knows what, and sleeping in Golden Gate Park (SF, CA); and another friend who contracted it at army boot camp.
Yes, it is a scary disease but I would do my research and be wary of over-imunizing. I didn't get it as it was not required, nor did my DH... and neither of us have gotten it even though exposed to it by two people at two different times.