Fatal Encephalitis Due to Variant B Human Herpesvirus-6 Infection in a Bone Marrow-Transplant Recipient

Human herpesvirus-6 (HHV-6) is the causative agent of exanthem subitum1 and febrile illnesses2 in children. More recently, HHV-6 has been shown to infect the recipients of bone marrow transplants and has been implicated in interstitial pneumonitis3,4 and bone marrow suppression5 after transplantation. The pathogenicity of HHV-6, however, has yet to be fully delineated in either immunocompetent or immunocompromised hosts. In some children with exanthem subitum, seizures, encephalopathy, and the detection of HHV-6 DNA in cerebrospinal fluid have provided circumstantial evidence that HHV-6 can infect the central nervous system6,7. Nevertheless, these studies have failed to document the direct . . .