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Primary human herpesvirus 6 infection in young children
P Pruksananonda1, C B Hall, R A Insel
1Department of Pediatrics, University of Rochester School of Medicine, N.Y. 14642-8689.
Insights
Primary human herpesvirus 6 (HHV-6) infection causes acute febrile illness in young children, often with viremia and varied symptoms. This study clarifies its clinical impact and viral persistence in mononuclear cells.
Area of Science:
- Virology
- Pediatrics
- Infectious Diseases
Background:
- Human herpesvirus 6 (HHV-6) infects most children by age three, but primary infection's clinical picture remains unclear.
- Early childhood febrile illnesses require better understanding of causative agents and their manifestations.
Purpose of the Study:
- To define the clinical manifestations of primary human herpesvirus 6 (HHV-6) infection in young children.
- To investigate the presence and characteristics of HHV-6 during acute febrile illness in pediatric patients.
Main Methods:
- Studied children aged two years or younger with febrile illnesses presenting to an emergency ward.
- Employed HHV-6 isolation from peripheral-blood mononuclear cells, immunofluorescent-antibody assay, PCR detection, and restriction-endonuclease-fragment profiling.
Main Results:
- HHV-6 was isolated from 14% of acutely ill children, who presented with irritability, high fever, and tympanic membrane inflammation.
- Viremia was common, with genomic heterogeneity observed among isolates; viral DNA was frequently detected by PCR during convalescence.
- Roseola-associated rash was infrequent, and most children recovered within four days, though viral genome persisted in mononuclear cells.
Conclusions:
- Primary HHV-6 infection is a significant cause of acute febrile illness in young children.
- Clinical presentations are diverse, often involving viremia and leading to frequent persistence of the viral genome in mononuclear cells.
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.