[A case of infectious mononucleosis due to Epstein-Barr virus with suspected reactivation of human herpesvirus 6].

A 24-year-old woman hospitalized with fever, general fatigue, and upper abdominal pain was found to have liver dysfunction and an increase in atypical lymphocytes in peripheral blood. Serum immunological studies showed positive Epstein-Barr virus (EBV) VCA IgM antibody and human herpesvirus 6 (HHV-6) IgM and IgG antibodies, and negative EBV VCA IgG and EBNA antibodies on admission. Liver function was back within normal limits 8 weeks after onset, EBV VCA IgM and IgG antibodies were positive, EBNA and HHV-6 IgM antibodies were negative, and the HHV-6 IgG antibody titer was 8 times higher than that on admission. This case was diagnosed as infectious mononucleosis due to EBV with suspected reactivation of HHV-6.