Encounter Hepatitis B

The hepatitis B virus is a DNA virus belonging to the Hepadnaviridae family of viruses. Hepatitis B virus is not related to the hepatitis A virus or the hepatitis C virus.
Some people with hepatitis B never clear the virus and are chronically infected. Approximately 2 billion individuals in the world have evidence of past or present hepatitis B, and 2.2 million people in the U.S. are chronically infected with hepatitis B. Many of these people appear healthy but can spread the virus to others.
Hepatitis B infection is transmitted through sexual contact, contact with contaminated blood (for example, through shared needles used for illicit, intravenous drugs), and from mother to child. Hepatitis B is not spread through food, water, or casual contact.
Serologic (blood) markers specifically for hepatitis B virus are used to diagnose hepatitis B viral infection. The blood tests can also identify the stage of the infection (past or present) and people who are at highest risk for complications.
Injury to the liver by hepatitis B virus is caused by the body's immune response as the body attempts to eliminate the virus.
In the United States, 95% of adults who get hepatitis B are able to clear the virus and cure themselves of infection. The remaining 5% of adults with acute hepatitis B go on to develop chronic hepatitis B. Those who acquire the infection in childhood are much more likely to have chronic infection. Chronic hepatitis B may lead to cirrhosis or liver failure. Approximately 15% to 25% of people with chronic infection will die prematurely as a result of the infection.
Progression of chronic hepatitis B viral infection occurs insidiously (subtly and gradually), usually over several decades. The course is determined primarily by the age at which the hepatitis B viral infection is acquired and the interaction between the virus and the body's immune system.
Treatment with current antiviral drugs suppresses viral reproduction in about 40% to 90% of patients with chronic hepatitis B. The medications are also effective in reducing inflammation and improving blood tests. This can delay or reduce complications such as cirrhosis. However, only about 50% of people achieve a sustained viral suppression, and relapse is common. The medications do not cure the infection.
Liver transplantation should be considered for patients with impending liver failure due to acute (initial) infection or advanced cirrhosis.
Hepatitis B is preventable through vaccination. All children should receive the vaccine. In addition, adults at high risk for hepatitis B should be vaccinated. Unvaccinated people who are exposed to hepatitis B should be evaluated by a physician to determine if they need specific immune globulin (HBIG

http://www.medicinenet.com/hepatitis_b/article.htm