Global Distribution of Hepatitis D Virus Genotypes: A Systematic Review

Context: Hepatitis D virus (HDV) infection, as the main coinfection in patients with chronic hepatitis B, leads to progressive liver disease. Elucidating the global distribution of HDV genotypes may be beneficial for the development of HDV vaccines and antiviral agents. Objectives: Through this systematic review, we aimed to present a clear picture of HDV genotype dispersal at the global and regional levels. Methods: A systematic search was performed in Scopus, PubMed, and Web of Science using the relevant keywords of hepatitis D and HDV genotype. The old HDV genotype classification (HDV I, II, and III) and African HDV genotypes (HDV-5, -6, -7, and -8) were used for showing the HDV genetic dispersion. The data of the country-level distribution of HDV genotypes were translated to the regional and global distributions of HDV genotypes. Results: Among all 1,318 unique titles, 71 studies were screened in the qualitative synthesis consisting of 77 records from 33 countries (sampling locations). In Africa, the most common genotype was HDV I, followed by African HDV genotypes. In Asia, the most frequent genotype was HDV II, followed by HDV I. In Europe and Oceania, the most common HDV genotype was HDV I, followed by HDV II and African genotypes. In the Middle East and North America, the most frequent HDV genotype was HDV I. In South America, the most common HDV genotype was HDV III, followed by HDV I and African genotypes. Conclusions: We found HDV I is distributed globally. Other HDV genotypes are observed regionally: HDV II mainly in East Asia, HDV III exclusively in South America, and African genotypes mainly in West Africa. PROSPERO #: CRD42018097296.