Increasing Incidence of Recent Hepatitis D Virus Infection in HIV-Infected Patients in an Area Hyperendemic for Hepatitis B Virus Infection

Hepatitis D virus (HDV) is a defective RNA virus that requires the presence of the hepatitis B virus (HBV) surface antigen (HBsAg) to infect the hepatocytes [1]. The prevalence of HDV infection varies widely with different geographic regions studied [2, 3], depending on the prevalence of HBV infection in the general population and the risk factors for HBV transmission. It has been estimated that approximately 5% of HBV carriers are coinfected with HDV, leading to an estimate of 15 million persons infected with HDV worldwide [2, 3]. The majority of HDV infections are acquired through parenteral and sexual routes [2, 3], both of which are also important routes for human immunodeficiency virus (HIV) transmission. Compared with patients who are at risk for sexually transmitted infections, patients who are injection drug users (IDUs) have a significantly higher prevalence of HDV infection, suggesting that HDV is more efficiently transmitted by injections of contaminated blood or diluent than by sexual intercourse [4]. HDV infection has been considered to be the most severe form of viral hepatitis [2, 5, 6], and treatment options for HDV infection are limited [2, 7]. HDV coinfection increases the risk for hepatitis flares and chronic hepatic complications [2]; furthermore, patients with HBV/HDV coinfection have a significantly increased risk for hepatocellular carcinoma compared with patients with HBV monoinfection and the general population [8]. HDV infection can occur simultaneously with acute HBV infection in patients without preexisting HBV infection (coinfection), or HDV infection may occur in those patients with chronic HBV infection (superinfection) [2, 5, 6]. Superinfection with HDV in patients with chronic HBV infection is more likely to cause chronic HDV infection, which may lead to episodes of hepatitis exacerbations, rapid progression of chronic liver disease, hepatic failure, and deaths. With the advent of combination antiretroviral therapy (cART) in 1996, the survival of HIV-infected patients has significantly improved, and many HIV/HBV-coinfected patients now live on to develop the late complications (including death) related to chronic hepatotropic virus infections [9]. Notably, among such hepatotropic viruses is hepatitis C virus (HCV), which is increasingly reported among men who have sex with men (MSM) in many developed countries because of the shared routes of transmission for HIV and HCV [10, 11]. However whether the same is true for HDV remains largely unknown, as HDV is less well studied. In this study, we aimed to investigate the incidence of and factors associated with recent HDV infection among HIV/HBV-coinfected patients in Taiwan, where the prevalence of chronic HBV infection is estimated to be 18%–20% among adults who were born before implementation of the nationwide HBV vaccination program in 1984 [12].