Vertical transmission of HCV infection: prospective study in infants born to HIV-1 seronegative women.

Objective: We performed a long-term prospective trial in infants born to HCV positive but HIV-1 negative women, with the aim of evaluating vertical transmission of HCV and correlated risks factors.

Methods: From April 1996 to May 2002, 50 women in the 3rd trimester of pregnancy or close to delivery we enrolled in the study. Anti-HCV antibodies were detected by 2nd and 3rd generation ELISA tests (ABBOTT HCV 2nd EIA generation and MEIA Abbot Labs, IL) . Reactivity was confirmed by a commercial immunoblot (Abbott Matrix HCV 2.0) ad HCV-RNA was detected by a nested-PCR technique. Infants were prospectively followed by clinical and laboratory tests (ALT levels, anti HCV Ab and HCV RNA) every 3 or 6 months for 16 to-80 months (average: 28.5 months).

Results: Twenty-eight of 50 women (56%) were found positive for HCV-RNA at delivery, and in 17/50 no risk factors for HCV infection were identified. Vertical transmission of HCV was detected in 3/28 infants born to viremic mothers (10.7%), while none of the 22 non-viremic mothers transmitted the infection to their children. Prolonged HCV seronegativity was documented in one of the three infected infants. During follow-up three other infants presented a single positive PCR value; one infant resulted HCV positive at 51 months of age. All infants were anti-HCV positive at delivery due to passive acquisition of antibodies, and in the 44 uninfected infants the antibody titres decreased progressively and became negative at various intervals (3-18 months).

Conclusion: The overall vertical transmission rate was 6% but the risk of transmission of HCV infection is limited to women that are HCV RNA positive at delivery. This study shows that vertical transmission of HCV infection possibly occurs in immunocompetent infants with no HCV antibodies detected in the serum. Furthermore, we emphasise that a prolonged follow-up is absolutely mandatory in order ot establish the occurrence of active infection.