IT sounds as if you were originally infected with the Epstein-Barr virus (EBV).

Is that correct?

Once you're infected with EBV, you carry the virus — usually in a dormant state — for the rest of your life. Periodically, however, the virus may reactivate. When this happens, the virus can be detected in your saliva — but you're not likely to become ill. Rarely, reactivated EBV may cause illness in people who have weak immune systems. (From the Mayo Clinic)