Statements from the Taormina expert meeting on occult hepatitis B virus infection.

Occult hepatitis B virus (HBV) infection is one of the most challenging topics in the field of viral hepatitis with its virological and clinical relevance being debated for more than 30 years. Initially described in the late 1970s, this form of hepatitis B infection has now been further characterised. In particular, in the last 10 years the application of highly sensitive molecular biology techniques has resulted in the elucidation of its virological features and possible clinical implications. It is noteworthy that there has been a steady and continuous increase in the number of publications on occult HBV infection, with many reviews, editorials and commentaries recently being published by journals covering different areas of bio-medical interest [1–32]. However, several aspects of occult HBV infection are still not resolved, even including the definition itself as well as a standardised approach for laboratory- based detection. An EASL endorsed international workshop on occult HBV infection was held in Taormina (Italy) on March 7–8, 2008. Invited presentations by experts and subsequent extensive discussions reviewed the virology and immunology of occultHBVinfection as well as its diagnosis and epidemiology, risk of transmission by blood transfusion or liver transplantation, risk of reactivation in conditions of immune suppression, its potential significance in promoting the progression of chronic hepatitis and thereby possible intervention strategies, and finally its possible role in the development of hepatocellular carcinoma (HCC). The final session of the meeting focused on discussion among the members of the faculty that produced a number of statements and recommendations that are the subject of this report.