Prolonged atypical illness associated with serological evidence of persistent Epstein-Barr virus infection.

Seven patients with prolonged atypical illness were followed up for more than a year. Sera taken during that period showed significantly increased titres of IgM antibodies against the viral capsid antigen (VCA) of Epstein-Barr virus (EBV). In four of the patients antibodies to the R component of the early antigen (EA) complex of EBV were clearly detectable. Only one of these seven patients had presented with symptoms of classic infectious mononucleosis. Serological and clinical observations in these patients suggest that the prolonged atypical illness was probably the result of persistent EBV infection.