Aims: To determine, from data obtained in a school-based hepatitis B vaccination programme, the prevalence of hepatitis B virus (HBV) infection in household contacts of children found to be hepatitis B surface antigen (HBsAg) positive.
Methods: Children who were HBsAg positive were visited in their homes 6 months or more after their initial blood test. Blood was drawn to confirm HBsAg status, and to ascertain HBeAg status. Their household contacts were tested for HBV seromarkers.
Results: Visits were made to homes of 931 children initially found to be HBsAg positive. Nine hundred and seven of these children (97.4%) were still HBsAg positive and thus confirmed to be chronic HBsAg carriers. The testing of 2957 household contacts of HBsAg positive schoolchildren revealed that 719 (24.3%) were HBsAg positive, a rate many times higher than that in the schoolchildren initially tested. Total HBV seromarker rates were highest in Asian households, and lowest in Europeans where 57% had been infected and 12% were HBsAg positive. Ethnic differences were largely accounted for by variation in maternal HBsAg status, reflecting different rates of perinatal infection.
Conclusions: All family and household contacts of individuals identified as presumptive HBsAg carriers should be tested for HBV seromarkers as a routine. It is particularly important to ensure full prophylaxis against perinatal infection.