STUDIES ON INTRA-FAMILIAL TRANSMISSION OF HEPATITIS-C VIRUS - AN EVIDENCE FOR TRANSPLACENTAL VERTICAL TRANSMISSION FROM MOTHER TO BABY

In order to clarify the mode of transmission of hepatitis C virus (HCV) within the same family, HCV markers and HCV genotypes in family members of 44 patients with chronic HCV-related liver diseases and in four neonates borne by HCV marker-positive mothers, were studied. The detection rate of HCV markers in the same family was very high compared to non-familial blood donor controls, indicating intra-familial accumulation of HCV infection. The coincidence rate of the HCV genotypes was 75% in four couples, and 33.3% in three pairs of mothers and children. HCV markers were not always positive in children from the same mother. Within 2 days of delivery, HCV-RNA was positive in two neonates from the four HCV-RNA-positive mothers. HCV genotypes in two neonates were the same as that of their respective mothers. In one neonate, HCV-Ab disappeared from blood during a 1-year observation period; however, HCV-RNA was persistently positive. These results suggest that vertical transmission of HCV from mothers to neonates occurs transplacentally. However, the coincidence rate of HCV genotypes between mothers and their children was low, suggesting that vertical transmission of HCV may occur only in a limited number of families. The low coincidence rate of HCV genotypes between mothers and their children suggests that shared family life, including medical treatment by the same doctor, may be more important than direct transmission for intra-familial accumulation of HCV infection.