The most common cause is infection with one of 5 viruses, hepatitis A, B, C, D, and E viruses. Hepatitis B is the most serious type of viral hepatitis. Some individuals may have an acute infection with no symptoms. Although most persons with acute hepatitis B infection recover completely, severe infection occurs in a small number, resulting in a high risk of death from the acute infection. Usually an infected person recovers and develops lifelong immunity.
Some people continue to carry the virus for life and become 'chronic carriers'.
Chronic carriers often appear and feel well and may not be aware that they are infected, yet they are capable of infecting others. Hepatitis B is transmitted by blood, by close personal or sexual contact and from pregnant mothers to their babies. The most effective strategy to control hepatitis B infection is through hepatitis B immunisation of infants and young children as early in life as possible to prevent infection. The hepatitis B vaccine, which is the first vaccine against liver cancer, is safe and effective. A direct reduction in liver cancer in immunised groups of children has already been demonstrated in Taiwan.