Hepatitis D infection in Nigeria

Abstract

Hepatitis D virus (HDV) is a defective RNA virus that requires the hepatitis B envelope for its replication. Infection with HDVoccurs as co-infection or superinfection in persons infected with hepatitis B virus (HBV). Chronic HDVinfection usually follows superinfection of chronic HBV infection with HDV. Unlike some other infections, persistent HDV infection is associated with presence of HDV RNA, viral antigen (HDAg), and IgM and IgG antibodies to HDV [1]. HDV has a worldwide distribution with nearly 15 million people infected, especially in the Mediterranean Basin, the Middle East, Central Asia, West Africa, the Amazon Basin of South America and certain South Pacific islands [2]. In Nigeria, HBV infection is a major cause of liver disease [3]. In a previous report, HDVantigen was detected in 6.5% of patients with chronic HBV liver disease in Ife, South West Nigeria [4]. With measures for preventing HBV infection (including vaccination and safe blood transfusion), HDV infection may be on the decline [5]. However recent reports, including one from our locality, have tended to indicate otherwise [6, 7]. We set out to investigate the current status of HDV infection. After ethical approval, consecutive consenting patients attending the Gastroenterology Unit of Lagos State University Hospital, Lagos between September 2009 to November 2010 were recruited if they were positive for HBsAg for more than 6 months and had not received any antiviral therapy. A questionnaire was used to collect information on demographics, clinical features, liver biochemical tests and imaging results. Blood (10 mL) was collected in EDTA, and plasma was separated and stored at −20 C. IgG anti-HDV antibodies were assayed using an Elisa method (HDVAb kit; DIA PRO Diagnostic, Milan, Italy) according to the manufacturer’s protocol. The sensitivity and specificity of this assay kit are over 98%. A total of 245 patients (191 male) with age range 13–76 (mean [SD]034.6 [10.6]) years were studied. Of these, 178 were asymptomatic HBV carriers, whereas 67 had features of chronic liver disease (chronic hepatitis 22, cirrhosis 37 and liver cancer 8). Five (2.0%; 2 male) of these 245 patients tested positive to anti-HDV. These included 3 of 178 asymptomatic carriers and 2 of 67 patients with liver disease. Alanine aminotransferase (ALT) levels were mildly elevated in two anti-HDV positive persons and were normal in three. Our study patients with chronic HBV infection had a lower prevalence of anti-HDV antibody as compared to previous reports [4, 7] from our locality with prevalence rates of 6.5% for HDAg and 12.5% for HDV antibody, respectively. Possible explanations for this difference may relate to the characteristics of the study subjects, the assay or an actual reduction in disease burden. Among the previous studies, one by Ojo et al. [4] had smaller sample size, consisted of patients symptomatic for liver disease and the assay was for HDV antigen. The other study [7] included both symptomatic and asymptomatic persons, but had a larger sample size. Our study, as well as both the previous studies, were limited by the fact that testing for HDV RNA, a better marker of HDV infection, was not done. A true reduction in HDV prevalence rates over time is also possible; this could have resulted from measures to prevent HBV infection embarked during the last two decades. A recent study showing HBsAg prevalence of about 8% Part of this work was presented as a poster during the EASL Monothematic Conference in Istanbul, Turkey in September 2010. C. A. Onyekwere (*) : F. Duro-Emmanuel Department of Medicine, Lagos State University Teaching Hospital, Lagos, Nigeria e-mail: ifymobi@yahoo.com