Hepatitis B infection is caused by hepatitis B virus (HBV). It is contracted from person to person through blood or bodily fluids contaminated with the virus. To become infected with hepatitis B, infected blood, semen, vaginal secretions or saliva must enter your body. You cannot become infected with hepatitis B through casual contact, like hugging, dancing, or shaking hands with someone who has hepatitis B. You also cannot be infected by:
Coming into contact with the sweat or tears of someone with hepatitis B
Sharing a swimming pool, telephone or toilet seat with someone who has the virus
Most damage from hepatitis B virus is caused by the body's response to the infection. The body's immune response against the infected liver cells damages them, causing liver inflammation, also known as hepatitis. As a result, liver enzymes leak out of the liver into the blood, causing transaminase blood levels to be elevated. The virus impairs the liver's ability to produce the clotting factor prothrombin, increasing the time required for blood clot formation. Liver damage also impairs the body's ability to rid itself of a breakdown product of old red blood cells called bilirubin.