High Prevalence of Isolated Hepatitis B Core Antibody among Adults in Oyo State, Nigeria: The Need for Review of Diagnostic and Vaccination Guidelines

Background: Ten years of neonatal immunization with hepatitis B vaccine has not had any significant effect on the prevalence of the disease in Nigeria.

Aim: To investigate hepatitis B virus (HBV) markers as potential risk factors for viral transmission.

Study Design: A pilot prevalence study.

Place and Duration of Study: Community centers in Ibadan and Ogbomosho, between July 2014 and September 2014.

Methodology: One hundred and ninety-two apparently healthy volunteers (61 men, 131 women: age range 11-88 years) were investigated for HBV serological/immunological markers using enzyme linked immunoassays with 99 - 99.7% and 98.4 - 100% for specificity and sensitivity respectively (Diagnostic Automation/Cortez Diagnostics, Inc., Calabasas, CA, USA). Also data were processed with the statistical package for the social sciences version 20.0 (SPSS Inc., USA).

Results: A prevalence of 22.9%, 14.6%, 19.3%, 90%, 53.6%, 6.8% and 22.9% was obtained for HBsAg, HBsAb, HBcAb-IgM, HBcAb-Total, isolated HBcAb, HBeAg, and HBeAb, respectively. Analysis of the lifetime exposure of 90% among participants showed that 44 and 103 have markers for present (HBsAg) and past (isolated HBcAb) infections respectively, while 26 recovered with evidence of surface antigen neutralizing antibodies (HBsAb) in their serum. Seropositivity for HBsAg was highest among males and the 21-30 years old, while the female gender and persons aged between 30 and 40 years accounted for the largest percentage of isolated HBcAb carriers. Although history of exposure to risk factors like scarification, tattooing, injection from quacks, surgery, blood transfusion, sharing of sharp instrument/tools and injection drug use was common among participants, only 15.6% took hepatitis B immunization. On the overall, the risk of HBV infection was significantly associated with scarification and sharing of sharp instruments and tools.

Conclusion: The study highlights potential risk associated with the current diagnostic guideline for hepatitis B status and advocates the need for immunization among susceptible unvaccinated population.