Hepatitis B virus infection and its transmission in preschool children.

In the present study, 2.5% of 367 preschool children has HBsAg positivity. Of 11 mothers who were HBsAg positive during the third trimester of pregnancy, 4 had babies (36.4%) who developed HBsAg positivity by 2.5-3 months of age (vertical transmission). Two babies born of HBsAg negative mothers, with history of jaundice during first trimester, were HBsAg negative. All the relatives of HBsAg positive cases screened were negative for HBsAg.