Occult Hepatitis B Infection among Blood Donors in Pointe Noire, Republic of the Congo

Background: Occult hepatitis B infection (OBI) is one of the most important transfusion safety issues and is considered a potential risk for hepatitis B virus (HBV) transmission. The aim of this study was to evaluate the prevalence and characteristics of OBI among blood donors in Pointe Noire. Methods: A cross-sectional study conducted among blood donors at Pointe Noire between October 2019 and May 2020. Blood samples from blood donors negative for hepatitis B surface antigen (HBsAg) were included. HBsAg and hepatitis B core antibodies (HBcAb) were done by ELISA. HBV DNA was detected by nucleic acid testing (NAT) and sequencing of preS1 region was done to determine HBV genotypes. Results: Out of 350 samples tested, 283 (80.9%) were males and 67 (19.1%) females. The mean age was 32.4 ± 12.3 years (range 18–60 years). The rate of anti-HBc was 33.43% (117/350) and the OBI prevalence was 2.3% (8/350). All samples were identified HBV genotype E and multiple mutations in preS1 region were observed in 75% of samples. Majority substitutions were: sA35E in 5 cases, sH44L and T52R in 4 cases, sR38G in 3 cases, S89T and Q92V in 2 cases, sN97R and I108L in 1 case. OBI rate and mutations were unrelated to gender, age, donor group and genotypes. Conclusions: This study highlights the significant prevalence of occult HBV in blood donors, indicating that HBsAg screening of blood donors is not sufficient and should be improved by anti-HBc and HBV DNA screening.