The distribution of hepatitis B virus (HBV) in the populations of island Southeast Asia is of medical and anthropological interest and is associated with an unusually high genetic diversity. This study examined the association of this HBV genetic diversity with the ethnogeography of the populations of the Indonesian archipelago. Whole genome analysis of 21 HBV isolates from East Nusa Tenggara and Papua revealed two recently reported HBV/B subgenotypes unique to the former, B7 (7 isolates) and B8 (5 isolates), and uncovered a further novel subgenotype designated B9 (4 isolates). Further isolates were collected from 419 individuals with defined ethnic backgrounds representing 40 populations. HBV/B was predominant in Austronesian-language-speaking populations, whereas HBV/C was the major genotype in Papua and Papua-influenced populations of Moluccas; HBV/B3 was the predominant subgenotype in the western half of the archipelago (speakers of the Western Malayo-Polynesian [WMP] branch of Austronesian languages), whereas B7, B8 and B9 were specific to Nusa Tenggara (Central Malayo-Polynesian (CMP)). The result provides the first direct evidence that the distribution of HBV genotypes/subgenotypes in the Indonesian archipelago is related to the ethnic origin of its populations and suggests that the HBV distribution is associated with the ancient migratory events in the peopling of the archipelago.

Hepatitis B virus (HBV) and hepatitis C virus (HCV) infections pose serious problems in terms of public health and clinical intervention in a country with approximately 250 million people, who live in more than 17,000 islands. Efforts to combat HBV and HCV have been made through the implementation of universal infant hepatitis B immunization, blood screening, and other health promotion actions, and building epidemiological data to develop intervention strategies. A nationwide study in 2013 revealed hepatitis B surface antigen (HBsAg) prevalence of 7.1%, which indicates that Indonesia has moved from high to moderate endemicity of hepatitis B, leaving the prevalence of 9.4% in 2007. The occurrences of new hepatitis B cases still continue in early childhood period, which may root from low coverage of birth-dose hepatitis B immunization in remote islands, and the potential mother-to-child transmission of HBV from HBsAg-positive pregnant mothers. Other problems still exist including the high HBV infection rates among young adults in remote islands, the presence of occult hepatitis B, as well as the substantial prevalence of HCV infection in general population, who do not have access to diagnosis and treatment. Effective preventive and control strategies are being developed tailored to the local capacity, infrastructures, socioeconomics, and culture, as well as geographical aspects of the country.