title: Diagnosis of human herpesvirus-6 infection in two patients with central nervous system complications.
abstract: BACKGROUND
  Although exanthem subitum (ES) is generally a mild, self-limiting disease of early childhood, some cases of ES are complicated by seizures and encephalopathy. The presence of human herpesvirus-6 (HHV-6) DNA in cerebrospinal fluid (CSF) of these patients suggests that HHV-6 can infect the central nervous system (CNS) causing encephalitis.
  
  
  OBJECTIVE
  To demonstrate HHV-6 infection in two patients with serious CNS complications. The patients, a child and an adult, failed to develop the characteristic rash normally associated with ES.
  
  
  METHODS
  Peripheral blood mononuclear cells (PBMCs) and CSF were examined for the presence of HHV-6 or viral DNA, using virus isolation techniques and the polymerase chain reaction (PCR). Serum samples were tested by immunofluorescence (IF) and enzyme linked immuno-sorbent assay (ELISA) for the presence of anti-HHV-6 IgM and anti-HHV-6 IgG respectively.
  
  
  RESULTS
  HHV-6 was isolated from the PBMCs of the adult patient and the presence of virus in these cells was confirmed using electron microscopy. HHV-6 DNA was detected in CSF taken early during the infection in both patients, together with anti-HHV-6 IgM antibodies and increasing levels of anti-HHV-6 IgG.
  
  
  CONCLUSIONS
  The diagnosis of HHV-6 infection in these patients was confirmed either by virus isolation or by the detection of HHV-6 DNA in the CSF, and the results of serology. These cases show that HHV-6 infection may result in serious CNS complications, in children and adults.
authors.affiliation: Clinical Virology Research Unit, Sir Albert Sakzewski Virus Research Centre, Royal Children's Hospital, Herston Road, Herston, Brisbane, Queensland 4029, Australia.
authors.forename: T P
authors.initials: TP
authors.lastname: Sloots
authors.forename: I M
authors.initials: IM
authors.lastname: Mackay
authors.forename: J H
authors.initials: JH
authors.lastname: Pope