[Human herpes viruses type 6 and 7; causative agents of, among others, exanthema subitum].

A serendipitous discovery during early AIDS investigations was human herpes virus type 6 (HHV-6). Two years later (1988) it was shown that HHV-6 and later on also HHV-7 are the causes of exanthema subitum, a childhood disease with previously unknown causation. HHV-6 and HHV-7 are the main cause of febrile seizures. It is assumed that 90% of children are infected before they are three years old. The viruses are also found in adults; HHV-6 may cause mononucleosis and hepatitis. HHV-6 and HHV-7 infect CD4+ cells and may influence the course of HIV infection. In AIDS patients HHV-6 and cytomegalovirus are often isolated together from the lungs, possibly because they activate each other. Another possibility is that the circumstances in the lungs are favourable to both. HHV-6 and HHV-7 infection may be serologically diagnosed. There is little experience with antiviral treatment.