Mother-to-infant transmission of GB virus C/hepatitis G virus: the role of high-titered maternal viremia and mode of delivery.

To study mother-to-infant transmission of GB virus C/hepatitis G virus (GBV-C/HGV), blood samples of infants born to carrier mothers were collected beginning 3 months after birth and were tested for GBV-C/HGV RNA until 1 year of age. Of 2046 mothers, 2.1% were positive for GBV-C/HGV RNA, and 25 of their infants were followed for a median of 12 months. Thirteen infants (52%) were viremic, and infection became persistent in all. Maternal GBV-C/HGV RNA levels of this group were >10(7) copies/mL. Nucleotide sequence comparison in 5 viremic mother-infant pairs revealed a homology of 93%-98.2%, and none delivered by elective cesarean section. In comparison, of the 12 uninfected infants' mothers, 10 had lower GBV-C/HGV RNA levels (mean, 5 x 10(4) copies/mL), and the remaining 2 high-titered mothers had elective cesarean section. Thus, high-titered maternal viremia and mode of delivery are closely associated with the mother-to-infant transmission of GBV-C/HGV to infants, and the infection usually becomes persistent.