ABSTRACT
A cross-sectional study of 540 married Akha and Lisaw women of reproductive age was conducted in Chiang Rai Province, Thailand, between June 1st and August 31st, 1999, in order to determine the seroprevalence of HBsAg and identify the risk factors for chronic HBsAg carriage. HBsAg was detected by the reverse passive hemagglutination technique (RPHA). Data were obtained by questionnaires and serological testing. There were 164 Lisaws and 376 Akhas: most were illiterate (88.71%) and the annual family income was < or = 9,999 baht (50.93%). The seroprevalence of HBsAg was 8.15%. Logistic regression analysis, controlling for possible confounding factors, revealed that one to five injections in the year prior to the study increased the risk of HBsAg carriage by a factor of 4.84 (95% CI = 1.42-16.49); more than six injections increased the risk by a factor of 5.84 (95% CI = 1.47-23.18).