Human herpesvirus 6 encephalitis

Abstract

Human herpesvirus (HHV) 6, the etiologic agent of roseola, is nearly universally acquired during childhood. The virus establishes lifelong infection, including within the central nervous system (CNS), and replicates within several CNS cell types. HHV-6 has been linked to CNS disease during primary infection, including febrile seizures and possibly hippocampal injury. HHV-6 may also be associated with neurologic disease later in life, particularly in transplant patients. Recent reports offer evidence that HHV-6 reactivation may underlie a characteristic limbic encephalitis syndrome following hematopoietic cell transplant; the cardinal features of this syndrome include memory loss, insomnia, electroencephalographic evidence of temporal lobe seizure activity, MRI signal intensity abnormalities of the mesial temporal lobe, and the syndrome of inappropriate release of antidiuretic hormone. HHV-6 DNA is frequently detectable by nucleic acid amplification tests in the cerebrospinal fluid and peripheral blood upon symptom onset, which may provide a screening strategy in high-risk patients. Possible associations of HHV-6 with meningoencephalitis, mesial temporal lobe epilepsy, and multiple sclerosis in apparently immunocompetent hosts are under investigation.

Rapid and simultaneous detection of 6 types of human herpes virus (herpes simplex virus, varicella-zoster virus, Epstein-Barr virus, cytomegalovirus, human herpes virus 6A/B, and human herpes virus 7) by multiplex PCR assay

“…Several anti-viral drugs that are effective for treating herpes virus infections have been developed and are now routinely used in treatment (1,2,18,19,21). However, because different human herpes viruses often elicit similar clinical symptoms, there is an increasing need for the accurate and timely diagnosis of herpes infections in order for these powerful antiviral drugs to be used effectively (5,7,14,15,22,26). Recently, a polymerase chain reaction (PCR) method has been developed that is specific for each virus and serves as a rapid diagnostic method.…”

Limbic encephalitis caused by Epstein–Barr virus: A case report

“…Limbic encephalitis syndrome following hematopoietic stem cell transplantation has also been linked to the reactivation of an underlying HHV-6 infection. There may also be a link between HHV-6 and mesial temporal lobe epilepsy in immunocompetent hosts which is under investigation [11]. Thus, our case is a very rare and unique case of limbic encephalitis caused by EBV without any history of malignancy or allogeneic hematopoietic stem cell transplantation.…”

A 16-year-old transplant patient with amnesia, insomnia, and visual hallucinations

“…1 Most patients are asymptomatic, but others develop roseola infantum or exanthem subitum or aseptic/ viral meningitis.…”

“…1,2 HHV-6 encephalitis is an early consequence of transplant, and may be more common with unrelated cord blood transplants (;16% vs ;3% of bone marrow or peripheral blood transplants) and higher at subsequent unrelated cord blood transplants (;30%).…”