title: Natural history of chronic HBV infection in West Africa: a longitudinal population-based study from The Gambia.
abstract: The natural history of chronic HBV infection in sub-Saharan Africa is unknown. Data are required to inform WHO guidelines that are currently based on studies in Europe and Asia.
  
  
  
  Between 1974 and 2008, serosurveys were repeated in two Gambian villages, and an open cohort of treatment-naive chronic HBV carriers was recruited. Participants were followed to estimate the rates of hepatitis B e (HBeAg) and surface antigen (HBsAg) clearance and incidence of hepatocellular carcinoma (HCC). In 2012-2013, a comprehensive liver assessment was conducted to estimate the prevalence of severe liver disease.
  
  
  
  405 chronic carriers (95% genotype E), recruited at a median age of 10.8 years, were followed for a median length of 28.4 years. Annually, 7.4% (95% CI 6.3% to 8.8%) cleared HBeAg and 1.0% (0.8% to 1.2%) cleared HBsAg. The incidence of HCC was 55.5/100 000 carrier-years (95% CI 24.9 to 123.5). In the 2012-2013 survey (n=301), 5.5% (95% CI 3.4% to 9.0%) had significant liver fibrosis. HBV genotype A (versus E), chronic aflatoxin B1 exposure and an HBsAg-positive mother, a proxy for mother-to-infant transmission, were risk factors for liver fibrosis. A small proportion (16.0%) of chronic carriers were infected via mother-to-infant transmission; however, this population represented a large proportion (63.0%) of the cases requiring antiviral therapy.
  
  
  
  The incidence of HCC among chronic HBV carriers in West Africa was higher than that in Europe but lower than rates in East Asia. High risk of severe liver disease among the few who are infected by their mothers underlines the importance of interrupting perinatal transmission in sub-Saharan Africa.
authors.affiliation: Medical Research Council (MRC) Unit, Banjul, The Gambia.|Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK.|Unité d'Épidémiologie des Maladies Émergentes, Institut Pasteur, Paris, France.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Shimakawa
authors.affiliation: Medical Research Council (MRC) Unit, Banjul, The Gambia.|Department of Hepatology, Imperial College London, London, UK.
authors.forename: Maud
authors.initials: M
authors.lastname: Lemoine
authors.affiliation: Medical Research Council (MRC) Unit, Banjul, The Gambia.
authors.forename: Harr Freeya
authors.initials: HF
authors.lastname: Njai
authors.affiliation: Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: Christian
authors.initials: C
authors.lastname: Bottomley
authors.affiliation: Medical Research Council (MRC) Unit, Banjul, The Gambia.|The Gambia Hepatitis Intervention Study, IARC, c/o MRC Unit, Banjul, The Gambia.
authors.forename: Gibril
authors.initials: G
authors.lastname: Ndow
authors.affiliation: Department of Hepatology, Imperial College London, London, UK.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Goldin
authors.affiliation: Medical Research Council (MRC) Unit, Banjul, The Gambia.
authors.forename: Abdoulie
authors.initials: A
authors.lastname: Jatta
authors.affiliation: Medical Research Council (MRC) Unit, Banjul, The Gambia.
authors.forename: Adam
authors.initials: A
authors.lastname: Jeng-Barry
authors.affiliation: MRC International Nutrition Group, MRC Keneba, West Kiang, The Gambia.
authors.forename: Rita
authors.initials: R
authors.lastname: Wegmuller
authors.affiliation: Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK.|MRC International Nutrition Group, MRC Keneba, West Kiang, The Gambia.
authors.forename: Sophie E
authors.initials: SE
authors.lastname: Moore
authors.affiliation: Ministry of Health and Social Welfare, Banjul, The Gambia.
authors.forename: Ignatius
authors.initials: I
authors.lastname: Baldeh
authors.affiliation: Ministry of Health and Social Welfare, Banjul, The Gambia.
authors.forename: Makie
authors.initials: M
authors.lastname: Taal
authors.affiliation: Medical Research Council (MRC) Unit, Banjul, The Gambia.|Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: Umberto
authors.initials: U
authors.lastname: D'Alessandro
authors.affiliation: Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: Hilton
authors.initials: H
authors.lastname: Whittle
authors.affiliation: Medical Research Council (MRC) Unit, Banjul, The Gambia.|The Gambia Hepatitis Intervention Study, IARC, c/o MRC Unit, Banjul, The Gambia.
authors.forename: Ramou
authors.initials: R
authors.lastname: Njie
authors.affiliation: Department of Hepatology, Imperial College London, London, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Thursz
authors.affiliation: International Agency for Research on Cancer (IARC), Lyon, France.
authors.forename: Maimuna
authors.initials: M
authors.lastname: Mendy
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D006528:Carcinoma, Hepatocellular / Q000453:epidemiology; D002353:Carrier State / Q000453:epidemiology*; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D005714:Gambia / Q000453:epidemiology; D006514:Hepatitis B Surface Antigens / Q000097:blood*; D006513:Hepatitis B e Antigens / Q000097:blood*; D019694:Hepatitis B, Chronic / Q000097:blood* / Q000453:epidemiology* / Q000635:transmission; D006801:Humans; D015994:Incidence; D007223:Infant; D018445:Infectious Disease Transmission, Vertical / Q000706:statistics & numerical data*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D015995:Prevalence; D012307:Risk Factors; D011795:Surveys and Questionnaires
chemical_list: D015415:Biomarkers; D006514:Hepatitis B Surface Antigens; D006513:Hepatitis B e Antigens
keywords: EPIDEMIOLOGY; HEPATITIS B; HEPATOCELLULAR CARCINOMA