Weil Medical College of Cornell University, New York, New York 10021, USA. mystoeckle@bigfoot.com
Human herpesvirus 6 is the causative agent of roseola infantum, a generally benign rash illness of infants. Most persons acquire HHV-6 infection by age 2 years, and HHV-6 infection is a common cause of fever and febrile seizures in infants. In adults, primary infection with HHV-6 can produce a mononucleosis-like illness and, more rarely, severe disease, including encephalitis. In addition to primary infections, HHV-6 can cause clinical illness during reactivation, particularly in immunocompromised persons.