1 INTRODUCTION
Blood components are used by health services around the world for the treatment of numerous clinical conditions. Therefore, the safety of blood products remains a major concern for blood collection centers, mainly due to transfusion-transmitted viruses (TTVs), such as hepatitis B virus (HBV). HBV is prevalent in blood donors worldwide and constitutes a serious global public health problem, especially in low- and middle-income countries (LMICs). Globally, more than 2 billion people, equivalent to about a third of the world population, have already been infected with HBV, of which 350 million people have developed chronic hepatitis infection. Geographic regions are classified as highly endemic (8%), intermediate (2 to 7%), and low endemic (<2%). The African continent is an area of high HBV endemicity compared to the other geographical regions.
Due to improvements in the criteria for selecting eligible donors for blood donation, the risk of transmitting viruses such as HBV has decreased significantly in recent years, even so, surveillance to estimate the risk of HBV transfusion in blood donors remains essential to monitor the safety of the blood supply as well as the impact of new screening tests, especially in areas of high HBV endemicity. HBV surface antigen (HBsAg) along with HCV, HIV, and syphilis screening remains the keys biological marker used for screening blood donors for sexual transmission infections. However, studies have shown that HBV mutations associated with structural changes in HBsAg and circulating immune complexes could negatively affect the performance of HBsAg detection, suggesting the inclusion of other biomarkers along with HBsAg although the cost and equipment requirements of these assays might limit their use in LMICs.
The biological markers aspartate transaminase (AST) and alanine aminotransferase (ALT) as well as the ratio of the AST/ALT have always been used in clinical practice to reflect liver injury and have been associated with some human diseases, including chronic diseases and mortality. Previous studies showed that serum determination of AST and ALT enzymes as well as their proportion is a clinically valuable procedure for differentiating viral hepatitis from other icteric diseases along with markers of infection, antibodies, and antigens. Despite the high endemicity of HBV in Angola, few studies have been carried out, for the screening of HBV infection in the asymptomatic or healthy population. To the best of our knowledge, there is no study published assessing the determinants of HBV infections along with the clinical profile of liver function in HBV-infected individuals in Angola. In this study, we combine sociodemographic and clinical features related to HBV infection as well as the clinical progression to chronic liver disease among HBV-positive blood donors rejected for blood donation in Luanda, the capital city of Angola, in order to (i) avoid the TTVs, (ii) improve the safe blood products, and (iii) control the spread of HBV infection in Angola. Furthermore, this study presents the epidemiological picture of HBV and could serve to reflect the status of HBV prevention and vaccination programs in Angola.