Occult hepatitis B virus infection among patients with chronic liver disease of unidentified cause, Addis Ababa Ethiopia

Occult hepatitis B virus infection (OBI) characterized by the absence of detectable HBsAg in the presence of HBV DNA in the serum and/or liver tissue remains a potential risk of transmission and diseases progression among different population groups. It could be associated with asymptomatic case up to chronic liver disease (CLD) and hepatocellular carcinoma (HCC). The objective of this study was to assess the magnitude and characteristics of OBI among patients with CLD of unidentified cause in Addis Ababa, Ethiopia. The study was conducted at the gastroenterology & hepatology referral clinic of three government and two private hospitals in Addis Ababa. Known CLD patients as evidenced by clinical and imaging criteria and/or with HBV surface antigen (HBsAg) negative results using rapid test kit were included. ELISA serological test to anti-HBc Ab, anti HBsAg Ab, and HBsAg were determined using BIORAD kits [https://www.bio-rad.com]. HBV-DNA was amplified, and viral loads were determined by quantitative real-time PCR using Abbott m2000rt platform following the manufacturer's instructions. Data analysis was done using SPSS version 20.A total of 48 CLD patients with no identified cause for their liver disease were identified during the study period. All the patients had evidence of CLD by clinical and imaging criteria and nine were excluded. Three (7.69%) of the 39 patients tested positive for HBsAg test done by ELISA making the negative predictive value of the rapid test kits 92.3% compared to ELISA. The remaining 36 patients had serology test for HBV and 16 (44.4%) had positive anti-HBV core antibody. Two (5.56%) of the 36 patients with HBV viral load determination had detectable HBV DNA suggesting presence of an occult hepatitis B infection. Occult hepatitis B infection is found to be an aetiology among CLD patients labelled as having no identified cause by the current standard of care using rapid HBsAg kits in a subset of patients in Ethiopia. This study signifies the high rate of OBI and past evidence of HBV infection among CLD patients and thus nucleic acid testing and/or anti-HBc shall be integrated to the routine health care system to minimize HBV infection risk of transmission and to enhance patient care.