The seroepidemiology of hepatitis in Papua New Guinea. I. A long-term study of hepatitis A.

Sera from 988 subjects in four ecologic zones of the Sepik district and 219 subjects from four widely spaced altitudes of the bismarck range in Papua New Guinea were tested for antibody to the hepatitis A virus (anti-HAV) by radioimmunoassay. The Sepik district subjects, mostly children between three months and six years of age when first sampled in 1963, were re-bled on four occasions over the ensuing nine years. The Bismarck range population was sampled only in 1964. In the Sepik district, anti-HAV was detected infrequently before the age of three years and showed maximum increase in prevalence rates between 7-10 years, with little increase thereafter. Antibody acquisition rates also indicated peak transmission in this age group, with fewer conversions between three months and six years of age and in adulthood. There was a consistent, though unexplained tendency for HAV infections to occur more frequently in proximity to the Sepik river than in areas farther away, and in the lower altitudes of the Bismarck range. As determined by serial samples, anti-HAV detected in 1963-1964 was still present in 1972 in 118 out of 119 subjects.