OCCULT HEPATITIS B VIRUS INFECTION IN BLOOD DONORS IN ILE-IFE, NIGERIA

Abstract

This study determined the prevalence of hepatitis B surface antigen (HBsAg) in blood donors. It measured the prevalence of total antibody to the hepatitis B core antigen (anti-HBc) in HBsAg negative blood donors, assessed the presence of HBV DNA in anti-HBc positive donors and investigated the risk factors for occult hepatitis B virus infection. It was with a view to assessing the burden of occult HBV in our environment and thereby forming a basis for instituting appropriate interventions.
The study protocol was approved by the Ethics and Research Committees of both Obafemi Awolowo University Teaching Hospitals Complex and Seventh Day Adventist Hospital. Relevant demographic information and risk factors were obtained from study participants with the aid of a structured, selfadministered, questionnaire. Ten millilitres of whole blood was collected from each of 507 blood donors who had already been screened using rapid test kits and declared fit for donation at the blood banks of both institutions. Plasma obtained was screened for HBsAg using ELISA and those negative were screened for anti-HBc also using ELISA. Those positive to anti-HBc were then tested for HBV DNA, using real-time PCR. Data on the number of blood donors screened for HBsAg during the period of the study and they were obtained from blood bank registers. Data were analysed using descriptive and inferential statistics.
One thousand and seventy three blood donors were bled during the study period. Of these 62 were positive for HBsAg using immunochromatographic rapid test kits, and when 507 of those HBsAg negative by rapid test kits were tested for HBsAg using ELISA, 5 (1%) were HBsAg positive. The total number found to be HBsAg positive including those missed by rapid test kits was 67 (6.2%). Of the 502 tested for anti-HBc, 354 (70.5%) were found positive implying exposure to HBV and 19 (5.4%) of these had HBV DNA signifying occult HBV infection. No specific risk factors were found to be associated with the presence of HBV DNA among those tested.
The study concluded that HBsAg prevalence is high and hepatitis B virus infection is still endemic with a large percentage of the population showing evidence of exposure to HBV in this environment. There is a relatively high burden of occult HBV infection in our environment and the use of HBsAg alone for screening either in blood transfusion services or stem cell transplantation does not eliminate the risk of HBV transmission.

OCCULT HEPATITIS B VIRUS INFECTION IN BLOOD DONORS IN ILE-IFE, NIGERIA