The Spectrum of Clinical and Laboratory Findings Resulting From Human herpesvirus-6 (HHV-6) in Patients With Mononucleosis-Like Illnesses Not Resulting From Epstein-Barr Virus or Cytomegalovirus

Am J Clin Pathol. 1990 Jun;93(6):776-83. doi: 10.1093/ajcp/93.6.776.


Recently, the morphologic, immunologic, and molecular makeup of a new virus designated human herpesvirus-6 (HHV-6) has been described. Because cell cultures of HHV-6-infected mononuclear cells showed prominent lymphocytic changes, it could be anticipated that mononucleosis-like illnesses or lymphoproliferative disorders would turn out to be manifestations of active HHV-6 infection. In the present study, blood samples from 27 patients previously categorized as having non-Epstein-Barr virus (non-EBV)/noncytomegalovirus (non-CMV) heterophil-negative mononucleosis-like illnesses were tested for IgM and IgG antibodies to HHV-6. Eight of these patients (30%) had serologic evidence of active HHV-6 infection. The clinical spectrum includes a short-lived febrile illness, mild cervical lymphadenopathy, laboratory data suggestive of active viral hepatitis in two patients, and a prolonged febrile illness in a single patient with previously documented positive anti-HIV serology. The viral studies revealed the presence of fourfold HHV-6-specific IgG titer increases by immunofluorescent assay (IFA) in seven serially studied cases and positive IgM serology on one or more samples tested by IFA or enzyme-linked immunosorbent assay (ELISA) in all eight cases. The authors could not determine whether the illnesses represented primary HHV-6 infections in susceptible individuals or reactivation of latent virus. HHV-6 serologic studies may be indicated in patients with mononucleosis-like illnesses with atypical lymphocytosis when EBV and CMV test results are nondiagnostic.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Antibodies, Anti-Idiotypic / analysis
  • Antibodies, Viral / analysis*
  • Child
  • Child, Preschool
  • Cytomegalovirus / immunology
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Follow-Up Studies
  • Herpesviridae Infections / blood
  • Herpesviridae Infections / immunology*
  • Herpesvirus 4, Human / immunology
  • Herpesvirus 6, Human / immunology*
  • Humans
  • Immunoglobulin G / analysis
  • Immunoglobulin M / analysis
  • Infectious Mononucleosis / immunology*
  • Male


  • Antibodies, Anti-Idiotypic
  • Antibodies, Viral
  • Immunoglobulin G
  • Immunoglobulin M