Prevalence and molecular characterization of occult hepatitis B virus in pregnant women from Gondar, Ethiopia

Molecular epidemiology of hepatitis B virus (HBV) in Ethiopia: A review article

Hepatitis B virus (HBV) belongs to the family Hepadnaviridae and is the smallest human DNA virus, with a genome that is only 3200 nucleotides long. The absence of proofreading function in HBV reverse transcriptase provides a wide range of genetic variants for targeted outgrowth at different stages of infection. A number of sub genotypes and ten HBV genotypes (A through J) have been identified through analyses of the divergence of HBV genomic sequences. Numerous clinical outcomes, including the emergence of chronicity, the course of the disease, the effectiveness of treatment, and the response to vaccination, have been related to differences in genotype between HBV isolates. There are just seven studies that have been done in Ethiopia that examine the molecular epidemiology of HBV. Moreover, these studies haven't been compiled and reviewed yet. In this review, we looked at the genetic diversity and molecular epidemiology of HBV, the relationship between HBV genotypes and clinical outcomes, the immunopathogenesis of HBV, and finally the molecular epidemiology of HBV in Ethiopia. PubMed, Embase, and Google Scholar search engines were used to find relevant articles for the review. By using HBV genotyping, clinicians can better tailor vaccination decisions and antiviral therapy for patients with chronic hepatitis B who are more likely to experience the disease's progression.

Genetic diversity and occult hepatitis B infection in Africa: A comprehensive review

BACKGROUND

Occult hepatitis B infection (OBI) is a globally prevalent infection, with its frequency being influenced by the prevalence of hepatitis B virus (HBV) infection in a particular geographic region, including Africa. OBI can be transmitted through blood transfusions and organ transplants and has been linked to the development of hepatocellular carcinoma (HCC). The associated HBV genotype influences the infection.

AIM

To highlight the genetic diversity and prevalence of OBI in Africa.

METHODS

This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and involved a comprehensive search on PubMed, Google Scholar, Science Direct, and African Journals Online for published studies on the prevalence and genetic diversity of OBI in Africa.

RESULTS

The synthesis included 83 articles, revealing that the prevalence of OBI varied between countries and population groups, with the highest prevalence being 90.9% in patients with hepatitis C virus infection and 38% in blood donors, indicating an increased risk of HBV transmission through blood transfusions. Cases of OBI reactivation have been reported following chemotherapy. Genotype D is the predominant, followed by genotypes A and E.

CONCLUSION

This review highlights the prevalence of OBI in Africa, which varies across countries and population groups. The study also demonstrates that genotype D is the most prevalent.

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.

Occult Hepatitis B Virus Infection and Its Risks of Cryptic Transmission in Southern Ethiopia

BACKGROUND

The detection of hepatitis B virus surface antigen (HBsAg) in serum remains the mainstay in diagnosing and screening of hepatitis B virus (HBV) in most developing countries. The absence of HBsAg in the blood may not indicate the absence of circulating HBV and might be infectious. Thus, this study aimed to estimate the burden and its cryptic transmission risks of occult hepatitis B infection (OBI) among HBsAg negative healthy individuals in Southern Ethiopia.

METHODS

A community-based cross-sectional study was conducted from September 2020 to January 2021. Serum samples were collected and assayed for HBsAg and HBV core antibody (anti-HBc) seromarkers using enzyme-linked immunosorbent assay (ELISA). In anti-HBc positive samples, HBV DNA was detected using real-time polymerase chain reaction (RT-PCR). Data were entered into Epi-Data version 3.1, cleaned, and analyzed using SPSS version 21.0. Descriptive and logistic regression analyses were employed. Statistical significance was decided at p < 0.05.

RESULTS

A total of 346 were individuals included in this study; 34 (9.8%) were tested positive for HBsAg. The rest 312 (90.2%) negatively tested were further assayed for anti-HBc, and 115 (36.7%) were found positive implying previous exposure to HBV, and 21 (18.3%) out of 115 anti-HBc positives had HBV DNA signifying OBI. The HBV DNA concentration below 200 IU/mL was 85.7%. A high rate of OBI was observed among individuals who had multiple sexual contacts, a family history of hepatitis, and tattooing.

CONCLUSION

In this study, the prevalence of OBI is high. This indicates the burden of HBV is considerable since screening is exclusively dependent on HBsAg which will not eliminate the possibility of residual cryptic transmission through blood donation, organ transplantation, perinatal transmission, and other contacts. Our results demonstrate that nucleic acid-based testing (NAT) should be an essential part of screening to prevent missing OBI.