A sometimes-fatal form of viral hepatitis caused by a double stranded DNA virus with genus Orthohepadnavirus of the family Hepadnaviridae. Hepatitis tends to persist in the blood serum. It can be transmitted through contact with infected blood products, sexual intercourse, and from mother to infant. The infection from Hepatitis B is much more severe than that of Hepatitis A and can occur as an asymptomatic carrier state, a chronic infection, or as cirrhosis of the liver. This virus can persist for extended periods of time, especially in asymptomatic carriers. The association of this integrated virus with hepatocellular carcinoma is now well established.