Intrafamilial transmission of hepatitis C virus in Japan.

To clarify the intrafamilial transmission of hepatitis C virus (HCV), the prevalence of antibody to HCV (anti-HCV) in 107 index patients with type C chronic liver disease was studied and compared with the prevalence of anti-HCV antibody in their 296 family members. Of the 85 index patients who were positive for anti-HCV, 15 (8%) of 196 of their family members were also HCV antibody positive, whereas of the 22 index patients who were anti-HCV antibody negative, none of the family members of the 100 evaluated was positive for anti-HCV antibody, a statistically significant difference between groups (P less than 0.02). No specific relative (spouse, child, parent, and sibling) was linked to HCV positivity in the index cases making it difficult to identify the route of infection that is believed to occur via the parenteral route in the home or community.