Transmission

The virus enters the body through a vein, a cut, or other break in surface tissue. After a period of 3 - 6 months (the incubation period), the first signs of infection are felt. The virus produces acute inflammation of the liver, which causes it to swell. This blocks the ducts that drain waste products from the liver. It also interferes with all other functions of the liver.
Hepatitis B is a highly infectious disorder and is spread in a number of ways:

• Having sexual intercourse with an infected person without using a condom.
• Sharing drug needles among users of injected street drugs.
• Tattooing may be a source of the infection.
• Accidental needle injury in health workers.
• Mother-to-child transmission of HBV during birth.
• Blood transfusions may transmit the virus if the blood donors have not been adequately checked. This is unusual in developed countries.
• Personal contact with an infected person. HBV, is sometimes spread when household members unknowingly come in contact with virus-infected blood or body fluids--most probably through cuts and scrapes or by sharing personal items such as razors and toothbrushes. While it is possible to become infected by contact with saliva, blood and semen remain the major sources of infection.
• In a small percentage of individuals the source of the infection remains unknown.