Hepatitis B virus infections in families in which the mothers are negative but the fathers are positive for HBsAg.

We studied a total of 37 families, in which HBsAg was positive in either or both of father and mother, to assess intra-familial transmission of hepatitis B virus (HBV). The HBsAg positive rate for children with HBsAg-negative mothers was significantly lower than that with positive mothers (4 of 31, 12.9% versus 18 of 32, 56.3%, p<0.01) of course. However, there were three families in which the infection source for children was thought to be fathers, not mothers, i.e., of eight children in these three families with HBsAg +/- father/mother pairs, 4 (50%) were positive for both HBsAg and HBV DNA of genotypes identical to those of their fathers, and another child was positive for HBcAb despite being negative for HBsAg. Interestingly, moreover, all the mothers in these three families were HBcAb-positive even though HBsAg-negative, suggesting that not only father-to-child but also inter-spouse HBV transmission might have occurred. With these findings we would suggest that all the family members with HBsAg-positive fathers should receive HBV vaccine, let alone for those with HBsAg-positive mothers.