Hepatitis B Antigen in Families of Blood Donors

The family members of 46 volunteer Red Cross blood donors positive for HB Ag were tested for HB Ag. The prevalence of positive relatives was 13%, compared with 0.15% in the donors. Seventeen of the 18 positive relatives were from families who originated in countries where the HB Ag carrier rate is high and only 1 was from countries where it is low. The prevalence of positive kindred from high-prevalence countries was 23%, and it seemed to be more related to ethnic origin than country of birth. Among the first-degree relatives the positive members were approximately equally distributed among siblings, parents, and offspring. None of 28 marital partners was positive. Whether the family clustering is owing to an epidemiologic or genetic relationship requires further study.