Hepatitis B Infection

 Hepatitis B virus currently infects more than 400 million people worldwide. Despite the availability of hepatitis B vaccine, the overall prevalence of hepatitis B virus infection has declined little in recent years. Hepatitis B virus causes liver injury by an immune response against the virus-infected liver cells and is not directly cytopathic, although immunosuppression appears to enhance replication and lead to direct cytotoxicity. The interplay of the host immune response and the virus’s ability to replicate is a prime determinant of the likelihood of liver injury, its intensity, and progression to cirrhosis. A series of stages evolve in the life cycle of each patient’s infection, with associated decreases in viral load at each successive stage