(CIT): Hepatitis B is a major cause of liver disease worldwide, ranking as a substantial cause of cirrhosis and liver cancer. In the United States, about 1.25 million people are chronically infected with the virus, resulting in 3,000 to 5,000 deaths each year. However, this condition occurs more frequently in high risk groups, including Asian Americans, emigrants from areas of the world where hepatitis B is common (China, Korea, Southeast Asia, the Indian Subcontinent, Africa, and Micronesia), men who have sex with men, injection drug users, and recipients of blood and blood products before screening procedures were implemented in 1986. Since routine hepatitis B vaccination of U.S. children began in 1991, new cases of acute hepatitis B among children and adolescents have dropped by more than 95%--and by 75% across all age groups. In non-protected individuals, transmission can result from exposure to infectious blood or body fluids containing blood. A major impediment to diagnosis is that many infected individuals are either asymptomatic or experience only non-specific symptoms of disease, such as fatigue or muscle ache. For approximately 90% of adults, acute infection with the hepatitis B virus is resolved by the body"s immune system and does not cause long-term problems. The transition from acute to chronic infection appears to occur when the immune system does not effectively destroy and clear virus-infected cells. This leads to high blood levels of both hepatitis B DNA and antigens, as well as antibodies produced by the body in an attempt to combat the infection. The natural history of the disease is not well understood, however, which makes management of this complex disease challenging. Many factors can influence treatment decisions for an individual patient, including age, ALT (alanine aminotransferase, a liver enzyme) level, viral load, liver biopsy results, and the presence of a co-infecting virus (i.e., HIV). Treatment decisions require in-depth analysis of multiple blood tests results, which are typically repeated at regular intervals to monitor the disease course. There are currently six approved therapeutic agents: interferon-alpha (Intron A), lamivudine (Epivir-HBV, Zeffix, and Heptodin), adefovir dipivoxil (Hepsera), entecavir (Baraclude), pegylated interferon (Pegasys), and telbivudine (Tyzeka and Sebivo), which are often used in combination. Generally, these drugs act to decrease the risk of liver damage from hepatitis B by slowing or stopping the replication of the virus. Questions remain as to which groups of patients benefit from therapy and at which point in the course of their disease. Specific recommendations for hepatitis B therapy are limited by a lack of reliable long-term safety and efficacy information. This is a difficult decision for physicians and patients, as treatments are expensive and may have bothersome, if not harmful, effects on patients; left untreated, however, chronic hepatitis B can lead to liver failure and other serious liver problems.