Human Herpesvirus 6

Excerpt

Human herpesvirus 6 (HHV-6) was first identified in the blood lymphocytes of adults with lymphoproliferative diseases or AIDS and was initially called human B-lymphotropic virus. The virus was later found in CD4+ lymphocytes and classified as a member of the herpesvirus family. As the sixth herpesvirus to be isolated, the organism was renamed human herpesvirus 6. Like other herpesviruses, HHV-6 establishes acute, persistent, and lifelong infections.

HHV-6 encompasses 2 genetically distinct double-stranded DNA viruses—HHV-6A and HHV-6B. These viruses are now considered separate species within the herpesvirus family. HHV-6A remains less understood but is more commonly detected in immunocompromised patients. In contrast, HHV-6B is the known cause of exanthema subitum (roseola infantum), a common childhood illness. HHV-6B infection is highly prevalent, with over 90% of individuals acquiring it by age 3, making it a frequent encounter in pediatric and emergency care settings.