Hepatitis B
• The Hepatitis B virus (HBV) is a small (3200 base pair) DNA virus
with a viral envelope. HBV replicates in the liver cells of humans and
other higher primates, and produces an excess of the viral envelope
protein (Hepatitis B surface antigen, HBsAg) that circulates in the
blood. HBV is transmitted by percutaneous and permucosal
exposure to infected blood or other body fluids, including semen
and vaginal fluids. In highly endemic areas, HBV is most commonly
spread from mother to child at birth, or from person to person in
early childhood. It has a worldwide distribution and currently more
than 2 billion persons have been infected, with approximately 360
million chronically infected. The outcomes of HBV infection are agedependent and persons with chronic HBV infection have a 15-25%
risk of dying prematurely from HBV-related causes include hepatitis,
liver cirrhosis, and hepatocellular cancer.