Epidemiology of the hepatitis delta virus (HDV) in West Africa: a systematic review

Background Hepatitis delta virus (HDV) represents the most severe form of chronic viral hepatitis yet remains neglected in resource-limited settings. West Africa, with high hepatitis B virus (HBV) endemicity and unique sociocultural risk factors, represents a critical region for understanding HDV epidemiology. This systematic review synthesizes evidence on HDV seroprevalence and genotype distribution across West African countries. Methods Following PRISMA 2020 guidelines, we searched PubMed/MEDLINE, Embase, Web of Science, Google Scholar, and African Journals Online (1984–2025) for studies reporting HDV seroprevalence, RNA positivity, or genotype distribution in West African populations. Two independent reviewers performed study selection and data extraction. Results From 2027 records, 40 studies (32,949 participants from 11 countries) met inclusion criteria. HDV prevalence among HBsAg-positive individuals ranged from 1.5% (Burkina Faso) to 46.2% (Benin), with descriptive regional average of 17.65%. Highest burden occurred in Benin (46.2%), Niger (33.6%), Mauritania (25.7%), and Guinea-Bissau (25.5%). Among 649 samples tested, 28.01% demonstrated active HDV RNA viremia, with highest rates in Senegal (61.5%) and Mauritania (59.9%). One Nigerian study reported HDV seropositivity among HBsAg-negative individuals (2.1% of participants). However, because occult hepatitis B infection was not investigated, this finding is not classified as HDV mono-infection in this review, as there could be the possibility of occult HBV infection, transient HBsAg negativity, or limitations in diagnostic sensitivity. Genotype analysis of 159 sequences revealed HDV-1 predominance (136 isolates), followed by African-specific genotypes: HDV-5 (19 isolates), HDV-6 (1 isolate) and HDV-7 (1 isolate). Only 10 of the 40 included studies performed molecular testing, representing a critical surveillance gap. Conclusions HDV remains highly endemic across West Africa, with one in six HBsAg-positive individuals showing HDV exposure and over one-quarter demonstrating active viremia among those tested. Significant circulation of African-specific genotypes reflects long-standing endemic transmission sustained by environmental and community-level factors. Urgent priorities include routine HDV screening among HBsAg-positive individuals, expanded molecular surveillance, with broader geographic coverage, and integrated prevention strategies addressing environmental risk factors in this high-burden region.