Occult HBV infection

The review focuses on terminology, causes, epidemiology, clinical significance of occult hepatitis B virus (HBV) infection (OBI). Attention is paid to the differences in the defi­nitions of OBI given by the European, American and Asian-Pacific associations for the study of the liver diseases. Current data are presented on various types of mutations that can lead to the development of OBI. The question is discussed about the presence of specific mutations that distinguish OBI from other forms of HBV infection, in which HBsAg may not be detected. The significance of OBI patients as sources of infection in transplantology and transfusiology is considered. Great attention is paid to the risk of OBI reactivation in patients with immunosuppression, as well as in co-infection of hepatitis C and human immunodeficiency viruses. Data are presented on the possible role of OBI in the occurrence of liver cirrhosis and hepatocellular carcinoma