HBV is a small circular partially double-stranded DNA virus of approximately 3200 base pairs. The virus can cause lifelong infection ,cirrhosis (scarring) of the liver ,liver cancer ,liver failure and death. The prevalence of HBV infection and the method of transmission vary greatly around the world.

The most common route of infection is from mother –to-child at birth or from child-to-child during early childhood. In areas of low prevalence, infection is usually acquired during adulthood through intravenous drug use or high risk sexual activity. The risk of developing chronic HBV infection from acute exposure ranges from 90% in newborns of HBV infected mothers to 25-30% for children under 5 and less than 10% in adults. Immunization is the most effective way to prevent HBV infection and can offer greater than 95% protection against the development of chronic infection.

Quantitation of HBV DNA is important in the evaluation and management of patient with chronic HBV infection. Current guidelines recommend HBV DNA viral load to determine which chronic HBV patients should be treated and to monitor their response to therapy. A low baseline viral load has been shown to be predictive of response to the therapy. Conversely, a high baseline viral load is predictive of resistance to therapy as well as relapse following therapy and has also been found to be an independent risk factor for hepatocellular carcinoma. Current treatment options include interferon, peginterferon and antiviral drugs such as lamivudine, adefovir and tenofovir.