Introduction to HHV-6
Human Herpesvirus 6 (HHV-6) is a set of two closely related herpes viruses known as HHV-6A and HHV-6B that infect nearly all human beings, typically before the age of two. The acquisition of HHV-6 in infancy is usually symptomatic, commonly resulting in childhood fever, diarrhea, and exanthem subitum rash (commonly known as roseola). Rarely, this initial infection will cause febrile seizures, encephalitis or intractable seizures.
Like the other herpesviruses—Epstein Barr virus, varicella virus, etc—HHV-6 establishes life-long latency and can become reactivated later in life. This reactivation has been associated with many clinical manifestations that can be seen in the “Associated Conditions” section of this site. Reactivation can occur in locations throughout the body, including the brain, lungs, heart, kidney and gastrointestinal tract. Although rare, HHV-6 reactivation in the brain tissue can cause of cognitive dysfunction, permanent disability and death.
A growing number of studies suggest that HHV-6 may play a role in subset of patients with several chronic neurological conditions including multiple sclerosis, mesial temporal lobe epilepsy, status epilepticus and chronic fatigue syndrome. There is an urgent need for more studies that can prove or disprove the important disease associations that have been suggested.
