Epidemiology of Hepatitis B Virus

Hepatitis B virus (HBV) is a double-stranded DNA hepadnavirus. It is an important cause of acute 5and chronic hepatitis and hepatocellular carcinoma. Worldwide about 2 billion people show serological evidence of exposure and about 400 million have active infection. High prevalence areas include sub-Saharan Africa, China, and southeast Asia. HBV was known at onset as the etiology of what is called “serum hepatitis”, this is the most common form of viral hepatitis transmitted parenterally. It is also a cause of both acute and chronic hepatitis of great significance. Hepatitis B virus has an incubation period that varies between 1 and 6 months. The clinical features of acute infection resemble those of the other viral hepatitides. Death from fulminant hepatitis occurs in about 1%. Following acute infection, there is either complete recovery (with long-term immunity) or persistent infection. The latter occurs in 5–10% infected adults, 30% infected children and 90% infants infected at birth; it is more common in the immunocompromised