Human Herpesvirus 6 and Febrile Convulsions.

Human herpesvirus 6 (HHV-6) is a ubiquitous virus that causes the childhood febrile illness exanthem subitum. Primary infection usually occurs in the first few years of life and the virus is considered to be one of the most common causes of acute febrile illness in childhood. HHV-6 can infect the central nervous system, causing meningitis or encephalitis after an acute attack of exanthem subitum. Febrile convulsions are common in early childhood, affecting 2--3% of children between 6 months and 5 years of age. Primary HHV-6 infection has been reported to be complicated by febrile convulsions in 8--50% of cases. An association between HHV-6 and febrile convulsions was established on the basis of: the similarity between the age groups in which febrile convulsions and HHV-6 infection occur, the high incidence of febrile convulsions after HHV-6 infection and the neurotropic properties of the virus. The exact role of HHV-6 in the pathogenesis of febrile convulsions remains unclear.