Markers of hepatitis B infection in Tari District, Southern Highlands Province, Papua New Guinea

Abstract

Serum samples collected from two groups in the Tari District of Southern Highlands Province were assayed for markers of hepatitis B virus (HBV) infection. 85% of women of childbearing age were found to have markers of HBV infection; 37% were positive for HBV surface antigen (HBsAg), indicative of the chronic carrier state, and 6.6% were positive for HBV e antigen (HBeAg), indicating the presence of actively replicating virus. 75% of women negative for HBsAg were positive for antibody to HBV core antigen (HBcAb), a marker of past infection. A group of children aged 6 to 18 years showed a significantly lower prevalence of markers of infection (66%) but higher rates of HBsAg positivity (46%) and HBeAg positivity (30%). Only 37% of the HBsAg-negative children in this group were positive for HBcAb. The results from this serosurvey suggest that the major route of HBV transmission in this population is horizontal, between older children, though significant transmission also occurs during the neonatal period.

PIP: The study was undertaken to obtain baseline information on the prevalence of markers for hepatitis B virus (HBV) infection among women of childbearing age and among children 6-18 years old residing in Tari District, Southern Highlands Province, Papua New Guinea. Blood samples were collected from females of child-bearing age attending maternal and child health clinics within the surveillance area of the Tari Research Unit during September 1990. Serum samples were assayed for the presence of hepatitis B surface antigen (HBsAg) using the Abbott Auszyme monoclonal enzyme immunoassay. All HBsAg-positive samples were tested for hepatitis Be antigen (HBeAg). Selected HBsAg-negative samples were assayed for antibody to HBV core antigen (HBcAb, a marker of past infection). Selected HBcAb-positive samples were screened for antibody to HBeAg (HBeAb, a marker of very recent, resolving infection). A total of 106 samples were screened for the presence of HBsAg. 39 (36.8%) were found to be positive. Of these, 7 (17.9%) were HBeAg-positive. 65 of the 67 HBsAg-negative serum samples were screened for presence of HBcAb, and 49 (75.4%) were positive. 56 samples collected in the Benaria area were screened for the presence of HBsAg. 26 (46%) were positive. Of the 26 HBsAg positive samples, 17 (65%) were HBeAg positive. Sera from the 30 HBsAg-negative children were tested for the presence of HBcAb. 11 (37%) of these samples were positive for HBcAb. 7 (64%) of the 11 were positive for HBeAb. The percentage of the sample showing markers for resolved infection (i.e. HBsAg-ve/HBcAb + ve) was only 20%, of these, 64% (7/11) showed evidence for very recently resolved infection (i.e., were HBeAb-positive). Of the children negative for HBsAg, 37% (11/30) were positive for HBcAb. The age distribution data for this series suggest that the peak age for transmission is between 9 and 11 years; in this age group 50% of children studied were HBsAg-positive, and 31% were HBeAg-positive.