TRANSMISSION OF HEPATITIS-C VIRUS FROM MOTHERS TO INFANTS

Background. Although there are case reports of vertical transmission o f hepatitis C virus (HCV), it remains uncertain to what extent infecte d mothers transmit this virus to their infants. Methods. We investigat ed the transmission of HCV from infected mothers to their babies by an alyzing HCV RNA in the blood. Three independent studies were performed . First, 7698 parturient women were tested for anti-HCV antibodies; 53 were positive. Their 54 infants (including one set of twins) were fol lowed prospectively for at least six months and tested for HCV infecti on. Second, the babies of six women with known HCV disease were prospe ctively studied. Third, the families of three HCV-infected infants wer e examined retrospectively. Results. Of the 53 antibody-positive mothe rs, 31 were also positive for serum HCV RNA, Three of the 54 babies bo rn to these mothers (5.6 percent) became positive for HCV RNA during t he follow-up period. None of the babies of the 22 women who were antib ody-positive but HCV RNA-negative became positive for HCV RNA. In the second study, HCV RNA was detected in one of the six infants of infect ed mothers. In the third study, HCV RNA was detected in the mothers of the three HCV-infected infants. In each of the seven infected infants we studied, the genomic sequence of HCV was almost identical to that from the mother. These seven mothers had significantly higher titers o f HCV RNA than did the mothers of infants with no evidence of infectio n (mean [+/-SD], 10(6.4+/-0.5) VS. 10(4.4+/-1.5) per milliliter; P<0.0 01). Conclusions. HCV is vertically transmitted from mother to infant, and the risk of transmission is correlated with the titer of HCV RNA in the mother.