Review of occult hepatitis b virus infection among nigerians: implications for blood transfusion medicine

Occult hepatitis B virus infection (OBI) has been recognized for over 30 years as a culprit in the transmission of hepatitis B virus to blood transfusion recipients. It is usually not detected using routine screening methods involving simple chromatographic antibody testing. In hepatitis B virus endemic regions such as Nigeria where blood for transfusion is still screened by chromatographic detection of HBsAg, the chance of transmitting the disease among Nigerians may remain high. This review aims to determine the prevalence of OBI among Nigerians and its implication on blood transfusion. A search of various databases including PubMed, African Journals Online (AJOL), Google Scholar, and Research Gate was undertaken for all articles on occult hepatitis B virus infections among Nigerians. Each article was screened for content to ensure that it addressed the subject under consideration. Articles that were considered fit for inclusion were those that employed the acceptable diagnostic criteria for OBI. The use of nucleic acid testing to detect HBV DNA in subjects who tested negative for HBsAg was a compulsory criterion for inclusion of an article. Articles that used recommendations from the Taormina committee were also considered and included in the review. Eight articles met our inclusion criteria. Seven out of eight studies were carried out among blood donors in Nigeria. There were four articles from the South-West region and three were from South-East. One of the studies from the South-East included data from the Federal Capital Territory (FCT), Abuja. The rate of OBI among blood donors in Nigeria ranged from 5.4% to 36% with a pooled prevalence of 18.5%.One article reported the prevalence of OBI to be 11.2% among HIV positive patients in Nigeria. Hepatitis B virus genotype E was the most predominant as reported by three articles. Other genotypes were A, non-A and mixed HBV genotype A/non A by two studies. Anti-HBs prevalence among OBI patients was reported as 9.5% to 64.3% with a pooled prevalence of 33.7% (95% Confidence interval 4.16-63.23). We concluded that there is significant risk of transfusion of HBV among Nigerians and this risk may remain high if more sensitive screening methods such as HBV DNA detection are not employed.