Congenital infections with human herpesvirus 6 (HHV6) and human herpesvirus 7 (HHV7).
OBJECTIVE
To examine whether: (1) congenital human herpesvirus 6 (HHV6) and human herpesvirus 7 (HHV7) infections occur; whether (2) their manifestations differ from postnatal infections; and whether (3) HHV6 and HHV7 infections differ despite their close relatedness.


METHODS
HHV6 and HHV7 infections acquired congenitally and postnatally in normal children were compared using viral isolation, serology, reverse-transcription polymerase chain reaction (RT-PCR) and nested DNA-PCR for HHV6 variant A (HHV6A), HHV6 variant B (HHV6B), and HHV7.


RESULTS
HHV6 DNA was detected in 57 (1%) of 5638 cord bloods. HHV7 DNA, however, was not detected in 2129 cord bloods. Congenital HHV6 infections differed from postnatal infections, which were acute febrile illnesses. Congenital infections were asymptomatic, 10% demonstrated reactivation at birth, and HHV6 DNA persistence in follow-up blood samples was significantly more frequent. One-third of congenital infections were HHV6A, whereas all postnatal infections were HHV6B.


CONCLUSIONS
Congenital HHV6 infections occurred in 1% of births, similar to the rate for cytomegalovirus infection. Congenital infections were clinically and virologically distinct from postnatal infections. Congenital HHV7 infections, however, were not detected, suggesting considerable differences in transmission and pathogenesis in these closely related beta-herpesviruses.
Department of Pediatrics, Cancer Center at the University of Rochester School of Medicine and Dentistry, Rochester, NY, USA. Caroline_Hall@urmc.rochester.edu <Caroline_Hall@urmc.rochester.edu>
Caroline Breese
CB
Hall
Mary T
MT
Caserta
Kenneth C
KC
Schnabel
Christian
C
Boettrich
Michael P
MP
McDermott
Geraldine K
GK
Lofthus
Jennifer A
JA
Carnahan
Stephen
S
Dewhurst
D000914:Antibodies, Viral / Q000097:blood; D002675:Child, Preschool; D018562:Disease Transmission, Infectious; D005260:Female; D005312:Fetal Blood / Q000821:virology; D005500:Follow-Up Studies; D015654:Herpesvirus 6, Human / Q000302:isolation & purification; D016199:Herpesvirus 7, Human / Q000302:isolation & purification; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D018445:Infectious Disease Transmission, Vertical; D008297:Male; D011446:Prospective Studies; D019349:Roseolovirus Infections / Q000151:congenital* / Q000635:transmission* / Q000821:virology
D000914:Antibodies, Viral