An Uncommon Case of Disseminated Human Herpesvirus 6 Infection in an Immunocompetent Adult.

Human herpesvirus 6 (HHV-6) is a common cause of infection in childhood, classically presenting as exanthema subitum. Viral reactivation causing severe disease in the setting of immunosuppression is well documented in the literature. However, HHV-6 infection in immunocompetent adults has been uncommonly reported. We describe the case of an immunocompetent man in his 50s who presented with fever, headache, confusion, and a truncal maculopapular exanthema with sparse vesicular lesions. Lumbar puncture results were compatible with viral meningoencephalitis. HHV-6 DNA was identified in cerebrospinal fluid, serum, and vesicular skin lesions by polymerase chain reaction testing, supporting a diagnosis of disseminated HHV-6 infection with central nervous system and cutaneous involvement. The patient received treatment with ganciclovir followed by oral valganciclovir, with complete recovery and no sequelae. This case highlights that HHV-6 may cause severe infection even in immunocompetent adults and underscores the need for evidence-based guidance to improve diagnosis and treatment of this condition.