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Original article
Natural history of chronic HBV infection in West Africa: a longitudinal population-based study from The Gambia
  1. Yusuke Shimakawa1,2,3,
  2. Maud Lemoine1,4,
  3. Harr Freeya Njai1,
  4. Christian Bottomley2,
  5. Gibril Ndow1,5,
  6. Robert D Goldin4,
  7. Abdoulie Jatta1,
  8. Adam Jeng-Barry1,
  9. Rita Wegmuller6,
  10. Sophie E Moore2,6,
  11. Ignatius Baldeh7,
  12. Makie Taal7,
  13. Umberto D'Alessandro1,2,
  14. Hilton Whittle8,
  15. Ramou Njie1,5,
  16. Mark Thursz4,
  17. Maimuna Mendy9
  1. 1Medical Research Council (MRC) Unit, Banjul, The Gambia
  2. 2Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK
  3. 3Unité d’Épidémiologie des Maladies Émergentes, Institut Pasteur, Paris, France
  4. 4Department of Hepatology, Imperial College London, London, UK
  5. 5The Gambia Hepatitis Intervention Study, IARC, c/o MRC Unit, Banjul, The Gambia
  6. 6MRC International Nutrition Group, MRC Keneba, West Kiang, The Gambia
  7. 7Ministry of Health and Social Welfare, Banjul, The Gambia
  8. 8Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
  9. 9International Agency for Research on Cancer (IARC), Lyon, France
  1. Correspondence to Professor Mark Thursz, Department of Hepatology, Imperial College London, Norfolk Place, London W2 1NY, UK; m.thursz{at}imperial.ac.uk.

Abstract

Background 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.

Methods 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.

Results 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.

Conclusions 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.

  • HEPATITIS B
  • EPIDEMIOLOGY
  • HEPATOCELLULAR CARCINOMA

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Footnotes

  • YS and ML contributed equally.

  • Contributors YS drafted the manuscript, and all the authors reviewed and approved it. HW initiated and MM maintained the cohort. YS, ML, RN and MTh were responsible for the design of the liver assessment 2012–2013; YS and AJ for fieldwork; ML, GN, and RN for clinical work; HFN and AJB for laboratory assays; RDG for histopathological analysis; YS and CB for statistical analysis. RW, SM, IB, MTa and UDA supported the conduct of the study.

  • Funding The Gambia government, MRC and European Commission's Seventh Framework Program (grant 265 994) supported the study.

  • Competing interests None declared.

  • Patient consent Obtained.

  • Ethics approval The study was approved by the Gambia Government/MRC Joint Ethics Committee and conducted according to the guidelines of the Declaration of Helsinki.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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