HHV-6B and HHV-7 in Exanthema Subitum and Related Skin Diseases

Primary human herpesvirus (HHV)-6B and HHV-7 infections can cause exanthem subitum, which is a common febrile exanthematous disease in childhood. Additionally, reactivation of the viruses has been implicated in skin manifestations. There are different incidence rates of exanthem subitum among patients with primary HHV-6B or HHV-7 infection in Japan and the United States. This disease is generally a benign, self-limiting disease, and it rarely causes complications such as febrile seizures and encephalitis. HHV-6B and HHV-7 reactivate in patients with drug-induced hypersensitivity syndrome (DIHS)/drug reaction with eosinophilia and systemic symptom (DRES), which has the clinical triad of fever, rash, and internal organ involvement due to drug exposure. Additionally, HHV-6B reactivation was associated with fever and skin rash or acute graft-versus-host disease in hematopoietic stem cell transplantation.