Severe Infectious Mononucleosis-like Syndrome and Primary Human Herpesvirus 6 Infection in an Adult

Human herpesvirus 6 (HHV-6) was first isolated from patients with the acquired immunodeficiency syndrome or lymphoproliferative diseases and was named human B-lymphotropic virus1. However, later studies revealed that the virus is T-lymphotropic in vitro2 and in vivo3. Recently, two genotypes of HHV-6 (type A and type B) have been distinguished on the basis of their restriction polymorphism4–6. HHV-6 has been identified as the etiologic agent of exanthem subitum in infants,7 and an acute febrile illness in young children8. Most people are seropositive for HHV-6 by the age of three years9,10. HHV-6 also produces . . .