Hepatitis A and B infections among expatriates in Papua New Guinea: A missed opportunity for immunization

Background: Hepatitis A (HAV) and hepatitis B (HBV) are hyperendemic among the indigenous population of Papua New Guinea (PNG), but little is known of the recent epidemiology of these diseases among the large number of expatriates living in PNG. Methods: The authors sought to determine the prevalence and rate of acquiring HAV and HBV antibody markers in expatriate missionaries, using a cross-sectional serosurvey method. Results: The authors entered 501 subjects into the study; the subjects had a mean time in-country of 100 months. Evidence for past infection with HAV was found in 47% of subjects (n=179) who had not received gamma globulin. Being a health care worker did not increase the probability of being HAV positive, but being a houseparent who cared for missionary children did (p=.06). Fifty percent of children <21 years old had positive HAV markers. Having a family member with a history of supposed "hepatitis" significantly increased the probability of being HAV positive (p=.0001). Evidence for past infection with HBV was found in 9.5% of subjects (n=46). Among those with evidence of past infection, 31% were <16 years old. Both infections are acquired more rapidly in children than in adults, and HAV is acquired more rapidly than HBV. Conclusions: Expatriates living in the hyperendemic setting of PNG have high seroprevalence rates for evidence of infection with HAV (47%) and HBV (9.5%). Children have rates of infection equal to, or greater than, adults in this setting. Expatriates living in countries with high endemic rates of HAV and HBV infection are at high risk of acquiring these infections and should be targeted to receive information about the risks of disease and the benefits of immunization.