Hepatitis B (HB) is an infectious disease caused by the hepatitis B virus (HBV) that affects the liver.
It can cause both acute and chronic infection. Many people have no symptoms during the initial infection. In acute infection, some may develop a rapid onset of sickness with vomiting, yellowish skin, tiredness, dark urine and abdominal pain.
Most of those with chronic disease have no symptoms; however, cirrhosis and liver cancer may eventually develop.
The virus is transmitted by exposure to infectious blood or body fluids. Infection around the time of birth or from contact with other people’s blood during childhood is the most frequent method by which hepatitis B is acquired in areas where the disease is common. About a third of the world population has been infected at one point in their lives. In Europe rates are 1.6% and in the Americas they are 0.7%. The disease is most common in the Western Pacific (6.2%) and African (6.1%) regions.