KOWSAR Jazayeri 3* A R T I C L E I N F O Article type: Review Article Article history: Received: 20 May 2012 Revised: 20 Jun 2012 Accepted: 8 Jul 2012 Keywords: Hepatitis B Hepatitis B Surface Antigens Coinfection Hepat Mon.2012;12(8):e6126. DOI: 10.5812/hepatmon.6126 www.HepatMon.com Occult Hepatitis B (OBH) in Clinical Settings Seyed Moayed Alavian 1, Seyed Mohammad Miri 1, F. Blaine Hollinger 2, Seyed Mohammad 1 Baqiyatallah Research Center for Gastroenterology and Liver Disease, Baqiyatallah University of Medical Sciences, Tehran, IR Iran 2 Baylor College of Medicine, One Baylor Plaza, Houston, TX, USA 3 Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, IR Iran A B S T R A C T Context: Occult hepatitis B (OHB), or persistent HBV DNA in patients who are hepatitis B surface antigen (HBsAg) negative, is a recently recognized entity. In an attempt to sum- marize the issues, this review presents an overview of the current proposed hypothesis on the clinical relevance and also updates the knowledge on the classification of OHB in different clinical settings. Evidence Acquisition: OHB could be found in different population and clinical back- grounds including: viral co-infections (with either human immunodeficiency or hepa- titis C viruses), HBV chronic carriers, dialysis patients, transplantation settings and certain clinical situations (named in here: special clinical settings) with no apparent distinguishable clinical parameters. Results: The exact magnitude, pathogenesis, and clinical relevance of OHB are unclear. Even the possible role exerted by this cryptic infection on liver disease outcome, and he- patocellular carcinoma development remains unknown. Conclusions: monitoring of Individuals with positive anti-HBc, mass immunization programs and improvement in diagnostic tools seem to be important to control the probability of transmission of HBV through cryptic HBV infection. Published by Kowsar Corp, 2012. cc 3.0. Implication for health policy/practice/research/medical education: Occult HBV infection has received increasing attention in recent years. Although the impact of occult HB in patients has not been determined, it appears to accelerate the progression of liver fibrosis and cirrhosis, ultimately leading to HCC. Occult HBV infection is unexpectedly frequent, in particular in hepatitis C virus (HCV) and in human immunodeficiency virus (HIV) infected individuals. This phenomenon has also been reported in blood transfusion settings. Therefore, OBH has a great impact on public health issues regarding blood safety, HBV diagnosis, etc. Please cite this paper as: Alavian SM, Miri SM, Hollinger FB, Jazayeri SM. Occult Hepatitis B (OBH) in Clinical Settings. Hepat Mon. 2012;12(8): e6126. DOI: 10.5812/ hepatmon.6126 1. Context 1.1. Occult Hepatitis B in Clinical Settings Occult hepatitis BHBV infection has been documented in a variety of clinical situations, especially among pa- tients who are positive for anti-HBc (Table 1). Occult HBV infection is also commonly present in HCC, chronic hepa- titis C virus (HCV) infection (1, 2), human immunodefi- ciency virus (HIV) infection (3), liver-transplant recipients of a liver from a donor who was antibody to the hepatitis B core antigen (anti-HBc) from core-antibody-positive * Corresponding author: Seyed Mohammad Jazayeri, Department of Virology, School of Public Health, Tehran University of Medical Sciences, P.O. Box: 15155-6446, Tehran, IR Iran. Tel: +98-2188992660, Fax: +98-2188992660, E-mail: jazayerism@tums.ac.ir DOI: 10.5812/hepatmon.6126 © 2012 Baqiyatallah Research Center for Gastroentrology and liver diseases; Published by Kowsar Corp. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which per- mits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.