In a review of 416 seizure patients <3 years of age, 24% had primary HHV-6 infections (Millichap 2006). Another study found that 43% of 35 febrile patients with seizures had HHV-6 infections . Another study of HHV-6 & 7 infections in hospital admissions in Britain and Ireland during the first two years of life (Ward et al, 2005) found that 17% of the encephalitis cases were associated with primary

infections of HHV-6 and 7, and that the two viruses were equally significant in these cases. One study in Japan found that of those patients with three or more seizures, 80% had evidence of HHV-6 in the spinal fluid compared with only 14% in patients with an isolated seizure (Kondo, 1993).

A recent study in Japan found that HHV-6 can result

in convulsions at the time of the rash outbreak following a primary infection with HHV-6. They propose calling this condition HEEC or “human herpesvirus-6 encephalopathy with cluster of convulsions in eruptive stage” (Nagasawa, 2006).