Hepatitis Bs Antigen (HBsAg) was detected in sera from children whose living conditions varied (25 elementary school children, 74 children from an orphanage, 28 children whose siblings had hepatitis and 40 children from a rural area).

HBsAg was found in 8% of normal healthy school children by CF technique and in 5% of rural area controls by RIA technique. The frequency of HBsAg was high among the children from an orphanage (24.3%) and among siblings of children who had hepatitis (17.7%). All these children lived in the same building or house, and they were in close contact with one another. Also none of these children had history of parenteral exposure. This seems to indicate that household contact and close physical contact are the most important factors in increasing the risk of HBsAg transmission.