Hepatitis B virus infects the liver of hominoiae, including humans, and causes an inflammation called hepatitis. It is a DNA virus and one of many unrelated viruses that cause viral hepatitis. The disease was originally known as "serum hepatitis"and has caused epidemics in parts of Asia and Africa. Hepatitis B is endemic in China and various other parts of Asia. The proportion of the world's population currently infected with the virus is estimated at 3 to 6%, but up to a third have been exposed. Symptoms of the acute illness caused by the virus include liver inflammation, vomiting, jaundice, and rarely, death. Chronic hepatitis B may eventually cause liver cirrhosis and liver cancer, a fatal disease with very poor response to current chemotherapy. The infection is preventable by vaccination.