National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

HHV-6 encephalitis


Other Names:
Human Herpesvirus 6 encephalitis; Variant A or HHV-6A; Variant B or HHV-6B
HHV-6 encephalitis refers to inflammation of the brain due to an infection with human herpesvirus 6.  People who have undergone allogeneic hematopoietic cell transplantation are at an increased risk for developing HHV-6 encephalitis, particularly when umbilical cord blood stem cells are used.  People with immune system disorders may also be at an increased risk for developing this infection. Signs and symptoms vary, but often include confusion, anterograde amnesia (difficulty learning new information following the onset of amnesia), short-term memory loss, and seizures. Diagnosis often involves lumbar puncture, virus testing, and MRI. EEG's may also be recommended when seizures are suspected. HHV-6 encephalitis is treated with an antiviral agent with activity against HHV-6. Long term outlook (chance of full recovery) can vary considerably depending individual patient factors.[1]
Last updated: 9/30/2013

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • ClinicalTrials.gov lists trials that are related to HHV-6 encephalitis. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • The HHV-6 Foundation provides information on HHV-6 and associated conditions on their Web site. Click HHV-6 Foundation to view the information.

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss HHV-6 encephalitis. Click on the link to view a sample search on this topic.

Selected Full-Text Journal Articles

  • Caserta MT, Mock DJ, Dewhurst S. Human herpesvirus 6. Clin Infect Dis. 2001 Sep 15;33(6):829-33. Epub 2001 Aug 10.

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  1. Zerr D. Human herpesvirus 6 infection in hematopoietic cell transplant recipients. In: Basow DS. UpToDate. Waltham, MA: UpToDate; 2013;