[An epidemiological study on prevalence and risk factors of hepatitis B virus (HBV) infection in preschool children].

A seroepidemiological survey was carried out in 5 kindergartens in Shanghai to determine the prevalence and risk factors of HBV infection in 520 preschool children, aged 2-6. Blood specimens were taken from all children and tested for HBsAg, anti-HBs and anti-HBc. The parents were inquired about exposure of the children to 24 possible risk factors, the data were analysed by Mantel-Haenzel's chi-square and Mantel extension chi-square. The prevalence of HBV markers was 21.73% (8.08% positive for HBsAg). It increased with age. There was no relationship between the presence of HBV markers and sex. HBsAg, especially HBeAg positive rate, in mothers was an important risk factor for children. The HBV prevalence was significantly higher for the children who had family members with a history of clinical Hepatitis. A two-fold R. R for premastication of food fed to the children had been demonstrated. This habit seemed to be a possible important risk factor in the family transmission of HBV.