I believe my son is O neg. What is CMV, and how do you know if you've had it? I know he's a sought after donor.
CMV is any of several viruses in the herpes family. It rarely causes serious illness in healthy adults; however, it can lead to serious consequences, incl. blindness, in those with depressed immune systems. In newborns CMV is the most common infection and a major cause of congenital deafness; it may also induce retardation and blindness.
Since the symptoms of CMV infection resemble mononucleosis, I would suggest that you check with your son's physician.