[Human herpesvirus 6. The etiological agent in exanthema subitum]

Human Herpesvirus 6 (HHV-6) is the sixth human pathogenic Herpesvirus. It was isolated for the first time in 1986. The virus is isolated from blood and saliva and it is probable that it is latent in salivary glands and possibly also in blood. The most probable route of infection is droplet infection via saliva and thereafter possibly by blood. Sero-epidemiological investigations demonstrate that newly born infants are practically all passively immunised via maternal antibodies. At about the age of six months, HHV-6 antibody can be demonstrated in a minority of children. From the age of two years and until 50 years, HHV-6 antibody is present in 90-100% of the population. This is in agreement with the extensive HHV-6 infection in the age group from six months to two years. It is demonstrated that HHV-6 is the cause of exanthema subitum. It is uncertain whether HHV-6 is of pathogenetic significance for other diseases.