Acute encephalopathy and status epilepticus associated with human herpes virus 6 infection.

A previously healthy 22-month-old boy presented in status epilepticus with high fever. He was comatose, with upper respiratory-tract infection. The seizures responded to anticonvulsant therapy. The boy's temperature returned to normal within 24 hours and he recovered slowly from his encephalopathy. On the third hospital day, he exhibited the characteristic rash of reseola infantum. Acute infection with human herpes virus 6 (HHV-6) was established serologically by enzyme immunoassay. HHV-6 DNA was not detected by polymerase chain reaction in CSF or serum at the onset of illness, but was found three months later in the child's saliva. The pathogenesis of the patient's encephalopathy is discussed. It is concluded that HHV-6 infection should be considered in infants and young children with febrile status epilepticus.