Hepatitis B is an inflammation of the liver that is caused by a virus. The virus spreads through contact with infected body fluids. Most people who get hepatitis B recover within a few months, but some develop chronic infection. Chronic infection increases one's risk for liver failure and liver cancer. Persons with chronic infection often have viral-related protein substances in their blood (called hepatitis B surface antigens and e antigens) for many years. When e antigen is present, it usually means that the person has very active liver disease and a lot of virus present. Eventually, the body's natural defense system clears e antigen in most persons and surface antigen in a small percentage of persons. Exactly how often the body clears hepatitis B antigens on its own and how many people with chronic infection develop liver failure and liver cancer are not completely understood.