Frequent seizures with elevated interleukin-6 at the eruptive stage of exanthema subitum.

A 15-month-old girl developed frequent seizures at the eruptive stage of exanthema subitum. The eruption persisted for 2 weeks. Serum immunoglobulin G antibody to human herpes virus type 6 (HHV-6) increased markedly. Interleukin-6 was elevated whereas HHV-6 deoxyribonucleic acid was not detected in cerebrospinal fluid. These findings suggest that immune-mediated reactions after HHV-6 infection rather than direct action of active HHV-6 are responsible for frequent seizures in this case.