Occult hepatitis B infection among blood donors from Yaoundé, Cameroon

Abstract

Background. In Cameroon, the prevention of hepatitis B virus (HBV) transmission by blood transfusion is still only based on hepatitis B surface antigen (HBsAg) screening. However, occult HBV infection (OBI) characterised by the absence of detectable HBsAg and low level of viral DNA remains a potential threat for blood safety. The prevalence of OBI was investigated in blood donors from Yaoundé to provide evidence-based recommendations to improve HBV blood safety.
Material and methods. Blood donations from August 1^st, 2016 to March 31^st, 2017 were routinely screened for HBV, human immunodeficiency virus (HIV), and hepatitis C virus (HCV) infections (Murex HBsAg Version 3, Murex HIV Ag/Ab Combination, and Murex HCV Ag/Ab Combination [DiaSorin]). Additional HBV investigations were performed, including hepatitis B core antibody ([HBc] Monolisa Anti-HBc PLUS; BIO-RAD) and HBV DNA tested in minipools of two samples using the quantitative Cobas Taqman HBV assay (Roche; LoQ: 6 IU/mL) and HBV DNA genotyping by sequencing.
Results. Of 1,162 donations analysed, 91 (7.8%) were reactive for HBsAg. All of them were also anti-HBc positive. Among the 1,071 HBsAg negative samples, 522 (48.7%) were reactive for anti-HBc. Six (0.56% of all donations) samples fulfilled the consensus definition of OBI and showed low HBV DNA loads (all <6 IU/mL). Following nested polymerase chain reaction amplifications, HBV DNA sequences were obtained for 4 of these samples (1 nearly whole genome [3123 nt], 2 Pre-S/S regions [1,356 nt], and 1 S region [445 nt]). Phylogenetic analysis identified genotype E in all samples.
Discussion. Around 1 in 100 Cameroonian blood donors screened who resulted HBsAg negative and anti-HBc positive carried occult HBV infection. HBsAg alone for screening prospective donors is not sufficient to eliminate the risk of HBV transfusion transmission in Cameroon, and because anti-HBc screening does not seem to be feasible without compromising blood supply, implementation of HBV nucleic acid testing could be considered when possible.