[Human herpesvirus 7]

Human herpesvirus 7 known since 1990 is closely related to herpesvirus 6B. It replicates in human cells only after binding CD4 receptor. It establishes lifelong latency in infected cells, and its frequent reactivations result in asymptomatic virus shedding through saliva. Most children acquire infection by age 3 and 4, but in any later age group seronegative individuals are at risk of infection. Rarely, exanthema subitum or convulsions with fever in children, pityriasis rosea in young adults, lethal complications in immunocompromised persons with concomitant herpesvirus 6B and cytomegalovirus reactivation occur. The most important pathogenic changes are due to the altered cytokine and growth factor secretion from infected lymphocytes with subsequent chain reaction on immune and other cells. Antiviral antibodies are detected by commercial kits (immunofluorescence, ELISA, immunoblot), nucleic acid by nested polymerase chain reaction. The majority of conditions due to infection do not require antiviral medication, but the severe complications are treated with ganciclovir and its derivates or foscarnet and cidofovir.