Sex-related differences in transmission of hepatitis B infection in a Melanesian population.

Abstract

Factors involved in the spread of hepatitis B virus (HBV) in the largely Melanesian population (N = 909) of Graciosa Bay, Ndeni, are examined. Based upon cultural information from Ndeni and ways in which HBV is spread in other populations, certain practices and interactions, predicted as effective routes of HBV infection, are analyzed. Most significant are father-to-son transmission and older-brother-to-younger-sibling transmission, indicating that males are instrumental in the transmission of HBV on Ndeni. Other possible routes of HBV transmission that are not shown to be significant on Ndeni are significant modes of disease spread in other cultures. Cross-cultural differences are discussed with regard to behavior, age of infection, and persistence of HBeAg (an antigen linked to HBV infection). Particularly with regard to maternal transmission, it is clear that the average age of infection combined with the degree of HBeAg persistence limits the number of infective mothers in this population. Cultural practices, however, may explain the disproportion of male carriers over 30 implicating a largely extinct set of culturally sanctioned practices involving very early exposure to HBV in boys and their age-related inability to make antibody to the virus.