Towards elimination of chronic viral hepatitis in French Polynesia: results from a national population-based survey

Abstract

Background: In French Polynesia, hepatitis B virus (HBV) infection appears as a major risk factor for hepatocellular carcinoma (HCC), which detection rate in the Austral archipelago is among the highest in the world. Through a nationally representative cross-sectional survey of the adult population, this study aimed at assessing the prevalence of HBV, but also hepatitis C virus (HCV), and hepatitis delta virus (HDV).

Methods: A total of 1942 blood samples from participants aged 18-69 years were tested for anti-HBc, anti-HBs, HBsAg, anti-HCV IgG, and HDV RNA. Complete genome sequencing of detected HBV strains was performed.

Findings: Among participants, 315/1834, 582/1834, 33/1834, 0/1857, and 0/33 tested positive for anti-HBc, anti-HBs, HBsAg, anti-HCV IgG, and HDV RNA, respectively. The population prevalence of HBsAg was estimated at 1.0% (95% CI: 0.6-1.7). All HBsAg carriers were born in French Polynesia before vaccination at birth became mandatory. In multivariate analyses, identified factors associated with HBsAg carriage included: the archipelago of residence (p < 0.0001), age (p < 0.0001), and education level (p = 0.0077). HBV genotypes B, C, and F were detected.

Interpretation: French Polynesia has a low endemicity level of HBV and its population may be considered at low risk for HCV and HDV infection. However, prevalence of HBsAg was found concerning in Austral (3.8%; 95% CI: 1.9-7.5) and Marquesas (6.5%; 95% CI: 3.8-11) archipelagoes. In the Austral archipelago, the presence of genotype C may account for the elevated rate of HCC. Our findings warrant more efforts to improve access to detection, prevention and care to people born before the systematic vaccination policy application, and residing in higher-risk areas, to achieve HBV elimination in French Polynesia.

Funding: Research Delegation of French Polynesia.

Keywords: Cross-sectional survey; French Polynesia; Hepatitis B; Hepatitis C; Hepatitis delta.

Fig. 1

Map showing the geographical distribution of the five archipelagoes of French Polynesia (Society, Tuamotu, Gambier, Marquesas and Austral). The 18 islands selected for the serosurvey are represented in red. N indicates the number of participants recruited in each island. Inset map at upper left shows location of French Polynesia (red circle) in the Pacific Ocean.

Fig. 2

Phylogenetic analysis of HBV strains isolated from the study participants. The phylogenetic tree was constructed using nucleotide sequences of the complete genome of HBV (3215 bp) obtained from the study participants (N = 18) and retrieved from GenBank (N = 20). The evolutionary history was inferred by using the Maximum Likelihood method based on the Kimura 2-parameter model. The percentage of trees in which the associated taxa clustered together is shown for values over 90 next to the branches (1000 replicates). Evolutionary analyses were conducted in MEGA 11.0.9. Sequences are labeled by country_ year of collection/GenBank accession number. Sequences obtained from inhabitants of the Marquesas, Austral, and Society archipelagoes are marked with green, red, and blue circles, respectively. HBV strains belonging to the same genotype (A–H) are delimited by brackets. Scale bar indicates nucleotide substitutions per site.