How prevalent is the mono in the us?

Very common. 2 out of every 1, 000 teens have had mono or been exposed to mono. By the time we hit our forties, about 95% of americans have been exposed to mono.
Mononucleosis. Over 95% of adults world wide are infected with the virus.. Overall incidence in the us is 500 cases per 100, 000, persons per year, with greatest incidence in 15 to 24 year old.