HHV-6, 7 and their related diseases.

Human herpesvirus 6 (HHV-6) and human herpesvirus 7 (HHV-7) are relatively recently discovered beta-herpesvirus. They are prevalent in the human population. Primary infection of HHV-6 has been associated with exanthem subitum and febrile illness. Little information is known about the clinical characteristics of primary infection with HHV-7, although some cases of exanthem subitum have been linked to it. HHV-6 has been recently recognized as an opportunistic pathogen in patients with HIV infection and in transplant recipients. The techniques now available to detect these two viruses remain limited, though putative roles for HHV-6 and HHV-7 in several diseases linked to viral infection have been reported. This report reviews the current knowledge of HHV-6 and HHV-7 biology and their pathogenesis.