Human herpesvirus 6 infection in febrile infants ninety days of age and younger

Background. The importance of human herpesvirus 6 (HVV-6) as a pathogen in febrile infants less than or equal to90 days of age is unknown. Objective. To determine whether febrile infants 90 days of age and younger evaluated for sepsis have evidence of HHV-6 DNA in plasma or cerebrospinal fluid (CSF). Methods. Febrile infants :590 days of age were tested for HHV-6 DNA using a real time quantitative fluorescent probe polymerase chain reaction assay. Results. Eighty samples from 47 infants were tested for HHV-6 DNA, 5 of 47 infants (10.6%) had EMV-6 DNA in plasma. In 2 of the 5 infants with HHV-6 DNA in plasma, HHV-6 DNA was also detected in the CSF. Both infants with evidence of HHV-6 DNA in plasma and CSF had HHV-6 Variant A infection. The quantity of HHV-6 DNA detected ranged from 70 to 169 000 DNA copies/ml. One infant with HHV-6 variant B infection had concomitant Escherichia coli bacteremia and urinary tract infection. Conclusions. Approximately 10% of febrile infants less than or equal to90 days of age evaluated for sepsis had evidence of HHV-6 infection. HHV-6 Variant A and B infections were seen in these young infants. HHV-6 DNA was found in infants with and without another explanation for fever. Quantification of viral DNA may be important in determining the relevance of HHV-6 DNA in clinical specimens.