title: Primary human herpesvirus 6 infection in young children.
abstract: BACKGROUND
  Human herpesvirus 6 (HHV-6) is a recently discovered virus that, on the basis of serologic evidence, appears to infect most children by the age of three years. However, the clinical manifestations of primary HHV-6 infection have not been well defined.
  
  
  METHODS
  We studied consecutive children two years old or younger who presented to an emergency ward with febrile illnesses. Our evaluation included the isolation of HHV-6 from peripheral-blood mononuclear cells, an immunofluorescent-antibody assay, the detection of HHV-6 by the polymerase chain reaction (PCR), and restriction-endonuclease-fragment profiles of HHV-6 isolates.
  
  
  RESULTS
  HHV-6 was isolated from 34 of 243 acutely ill children (14 percent). The children with viremia had irritability, high temperatures (mean, 39.7 degrees C), and inflammation of tympanic membranes (in 21), but few other localizing signs. Two children were hospitalized, but all 34 recovered after an average of four days of fever. The rash characteristic of roseola, which has been associated with HHV-6 infection, was noted in only three children. In 29 children (85 percent), serum samples obtained during convalescence had at least a fourfold increase in IgG antibody titers; 4 infants less than three months old who presumably had maternal antibody did not have this increase. HHV-6 was isolated from blood obtained during convalescence in only one child, but in two thirds of the children the virus could be detected by PCR. The isolates had genomic heterogeneity, indicating the presence of multiple strains.
  
  
  CONCLUSIONS
  Primary infection with HHV-6 is a major cause of acute febrile illness in young children. Such infection is associated with varied clinical manifestations, viremia, and the frequent persistence of the viral genome in mononuclear cells.
authors.affiliation: Department of Pediatrics, University of Rochester School of Medicine, N.Y. 14642-8689.
authors.forename: P
authors.initials: P
authors.lastname: Pruksananonda
authors.forename: C B
authors.initials: CB
authors.lastname: Hall
authors.forename: R A
authors.initials: RA
authors.lastname: Insel
authors.forename: K
authors.initials: K
authors.lastname: McIntyre
authors.forename: P E
authors.initials: PE
authors.lastname: Pellett
authors.forename: C E
authors.initials: CE
authors.lastname: Long
authors.forename: K C
authors.initials: KC
authors.lastname: Schnabel
authors.forename: P H
authors.initials: PH
authors.lastname: Pincus
authors.forename: F R
authors.initials: FR
authors.lastname: Stamey
authors.forename: T R
authors.initials: TR
authors.lastname: Dambaugh
mesh_terms: D000914:Antibodies, Viral / Q000032:analysis; D001483:Base Sequence; D003289:Convalescence; D005334:Fever / Q000209:etiology; D005455:Fluorescent Antibody Technique; D006566:Herpesviridae Infections / Q000175:diagnosis / Q000503:physiopathology; D015654:Herpesvirus 6, Human / Q000302:isolation & purification; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D007223:Infant; D007963:Leukocytes, Mononuclear / Q000382:microbiology; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000032:analysis; D016133:Polymerase Chain Reaction; D014766:Viremia
chemical_list: D000914:Antibodies, Viral; D007074:Immunoglobulin G; D010446:Peptide Fragments