Validation Of Hepatitis B Surface Antigen (Hbsag) Rapid Test To Screen Hbv Infection In Rural Gambia

Background: Sub-Saharan Africa (SSA) is highly endemic for HBV infection; yet rapid tests for HBs Antigen (HBsAg) detection have been poorly validated. Here, using the field experience of the PROLIFICA programme, we assessed the performances of two HBsAg point-of-care tests (POC) at the community level, in the Gambia, West Africa Methods & Materials: The PROLIFICA programme aims at screening and treating the population for HBV infection in West-Africa. In Gambian rural communities, we evaluated in parallel two POCs (Determine®(TM) and VIKIA®,) for HBsAg detection. Dried Blood Spots were also systematically collected during the screening and were used for Axsym HBsAg enzyme-linked immunosorbent assay (ELISA) for confirmation and comparison. Tests performances were based on Sensitivity (Se), specificity (Sp), positive and negative predictive values (PPV, NPV). Results: 242 persons were screened in the field, 30 (12.4%) patients tested positive with both POCs. Only one participant had discordant rapid test results. Using Asyxm ELISA, 34(14%) were HBsAg-positive giving the following Se and Sp for Determine 88.2% and 99.0% respectively; and 91.2% and 99.0% for Vikia®. The negative predictive values for both tests exceeded 98%. Conclusion: In this African rural setting, Determine and Vikia tests showed slightly lower performances than expected. However, both tests seem to be sensitive enough to screen easily and quickly the population for HBV infection in high endemic African settings. These cheap tests may pave the way for better access to care and treatment in highly endemic African poor settings.