Predictive risk factors for Hepatitis B virus infection among children in Mongolia: A nationwide survey

Background: Although Mongolia is endemic country of HBV infection, information regarding risk factors for this infection is insufficient. The aim of this study was to determine the risk factors for HBV infection among children. Methods: A nationwide cross-sectional survey was conducted in 2010. Sampling was multistage, random cluster with probability to population size. Serum samples were tested for HBsAg using a rapid test from Abbott© Japan. A standardized questionnaire regarding the socio-demographic characteristics and potential risk factors for HBV transmission was administered. Multivariate logistic regression analysis was used to identify predictors of HBV infection. Results: A total of 5894 children (51.8% boys) aged 4-6 years (mean ± SD: 5.0±0.8 years) was enrolled in this survey from 3 largest cities, 11 rural provinces and 50 villages. In a multivariate logistic regression analysis, adjusted for age, sex and residence the history of surgery (OR=3.26, 95% CI: 1.12-9.55; p=0.031), blood test (OR=2.93, 95% CI: 1.40-6.15; p=0.004), ear piercing for girls (OR=3.58, 95% CI: 1.06-12.1; p=0.04) were significant predictors for HBsAg positivity. All the mothers of HBsAg-positive children were positive for HBsAg whereas none of the mothers of HBsAg-negative children were positive for this antigen. In addition, history of blood transfusion, injection at the hospitals, and cohabitating with patients of chronic hepatitis have increased the risk but without statistical significance. Conclusions: The results suggest that vertical transmission of HBV is still occurring despite the mass infant vaccination in Mongolia. Parenteral transmission at the health care centers also play significant role in the HBV infection among children.