Seroprevalence and factors associated with hepatitis B infection among the hill tribe adult population in Thailand: a cross-sectional study.

Background: Hepatitis B virus (HBV) infection is one of the greatest public health burdens, particularly for people living with several barriers to access to health care services, such as the hill tribe adult population in Thailand. People aged 25 years and over who are out of the target population for HBV immunization under the national Expanded Program on Immunization (EPI) are at risk of HBV infection. The study aimed to estimate the prevalence and determine the factors associated with HBV infection among hill tribe adults aged 25 years and over living in Chiang Rai Province, Thailand.

Methods: A cross-sectional study design was used to collect information on hill tribe adults aged 25 years and over living in 36 selected hill tribe villages in Chiang Rai Province. All people living in the selected villages who met the criteria were invited to participate in the study. A validated questionnaire and a 5-mL blood specimen were used as research instruments. Hepatitis B surface antigen (HBsAg), antibody to hepatitis B surface (anti-HBs), and antibody to hepatitis B core (anti-HBc) were detected by using the Wondfo Test Kit, which has high sensitivity and specificity. Logistic regression was used to detect the associations between variables at the significance level of α = 0.05.

Results: A total of 1491 individuals were recruited into the analysis; 60.8% were females, 81.3% were aged between 30 and 60 years, and 86.0% were married. The majority were illiterate (54.9%), were Buddhist (55.7%), worked in agricultural sectors (87.3%), and had an annual income of less than 50,000 baht per year (72.9%). The overall prevalence of hepatitis B infection was 26.6%; 7.6% were positive for HBsAg, 19.2% were positive for anti-HBs, and 18.9% were positive for anti-HBc. In the multivariate analysis, three variables were found to be associated with hepatitis B infection: those who were in the Yao and Lisu tribes had a 1.64-fold (95% CI = 1.08-2.49) and a 1.93-fold (95% CI = 1.10-3.31) greater chance, respectively, of HBV infection than did those in the Karen tribe; those who were Christian had a 1.41-fold (95% CI = 1.06-1.87) greater chance of HBV infection than did those who were Buddhist; and those who did not use alcohol had a 1.29-fold (95% CI = 1.01-1.65) greater chance of HBV infection than did those who used alcohol.

Conclusions: It is necessary to develop and implement effective public health interventions among hill tribe adult populations who are not part of the EPI-targeted population, particularly Christians, those in the Lisu and Yao tribes, and those who do not use alcohol, to reduce the HBV infection rate, save lives and reduce medical expenses.