Occult hepatitis B virus infection of hemodialysis patients: a cross-sectional study in a hepatitis B virus-endemic region.

Occult hepatitis B virus (HBV) infection is defined as the presence of HBV DNA in the liver tissue and/or serum of subjects seronegative for hepatitis B surface antigen (HBsAg). Occult HBV infection of hemodialysis (HD) patients is informative in terms of virus transmission, reactivation after kidney transplantation, and the progression of liver disease. However, there is little detailed information about occult HBV infection in the context of virus endemicity. We tried to investigate the seroprevalence and clinical features of occult HBV infection in HD patients in HBV-endemic regions. We enrolled a total of 159 HD patients and 121 apparently healthy subjects at Dankook University Hospital and Jeju National University Hospital in Korea. HBsAg, anti-HBs, anti-HBc, and anti-hepatitis C virus (HCV) antibody levels were measured by radioimmunoassay. Serum levels of HBV DNA were measured by real-time polymerase chain reaction. The seroprevalence of occult HBV infection was 1.3% in HD patients and 2.5% in the healthy controls. This difference was not significant. The HBV load in all subjects with occult infection was <116 copies/mL, and all were positive for IgG anti-HBc, regardless of the presence of anti-HBs. None of the occult HBV-infected subjects were co-infected with HCV. One of the 2 HD patients with occult HBV infection had no history of blood transfusion. In this HBV-endemic region, the seroprevalence of occult HBV infection in HD patients with a very low viral load was not significantly different from that in apparently healthy subjects.