Prevalence of hepatitis B infection among the primitive tribes of Andaman & Nicobar Islands

Background & Objectives : Andaman and Nicobar Islands, is the home of six p rimitive tribes. No information is available on the prevalence of hepatitis B virus (HBV) infection among them. Hence a study was undertaken with the objective of assessing the sere-prevalence of HBV infection among the four accessible tribes of these islands. Methods : A total of 1266 serum samples were collected from four tribes i.e ., Nicobarese, Shompens, Onges and Great Andamanese and tested for the pres ence of HBsAg and anti-HBs. Information about different risk factors associ ated with HBV infection was also collected from the Nicobarese tribe. Results : The overall seropositivity rate of HBsAg among the Nicobarese was 23.3 per cent (95% C.I. 21.0 - 25.9). Hepatitis B was also found to be an important health problem among the Shompens and Onges with HBsAg positivity of 37.8 and 31.0 per cent respectively. The ape-wise distribution of these serological markers among Nicobarese tribe indicate that the infection is very common in all the age groups. The sere-prevalence was also found to be very high among the children. Conclusions & Interpretation : The findings of the present study indicate t hat hepatitis B infection is hyper endemic among the primitive tribes of th ese islands. Though none of the risk factors studied in the Nicobarese was found to be significantly associated with HBV infection, the fact that almo st 20 per cent of the women in the reproductive ape group were positive for HBsAg indicates the possibility of vertical transmission among the Nicob a rese. Further studies are required to find out other modes of transmission.