Hepatitis B is a potentially serious form of liver inflammation due to infection by the hepatitis B virus. It occurs in both rapidly developing (acute) and long-lasting (chronic) forms, and is one of the commonest chronic infectious diseases worldwide (the others are the hepatitis A virus and the hepatitis C virus)
A person who is chronically infected with the hepatitis B virus is called a “carrier” of the virus. The risk is maximum for infants born to mothers who are hepatitis B carriers: without immediate vaccinations, approximately 90% of these babies will develop chronic hepatitis B infection. Hepatitis B carriers have not developed immunity as a result of infection and may have traces of the hepatitis B virus in their blood and body fluids for the rest of their lives. At times, there may be ongoing liver damage and at other times, infection may be inactive. Most carriers do not appear sick and remain symptom-free but some will develop cirrhosis and/or liver cancer years after becoming infected with the hepatitis B virus.