Definition of Hepatitis B:

Hepatitis B is irritation and swelling (inflammation) of the liver due to infection with the hepatitis B virus (HBV).

Other types of viral hepatitis include:

• Hepatitis A
• Hepatitis C
• Hepatitis D

See also:

• Autoimmune hepatitis
• Chronic persistent hepatitis
• Drug-induced hepatitis

Causes, incidence, and risk factors:

Hepatitis B infection can be spread through having contact with the blood, semen, vaginal fluids, and other body fluids of someone who already has a hepatitis B infection.

Infection can be spread through:

• Blood transfusions (not common in the United States)
• Direct contact with blood in health care settings
• Sexual contact with an infected person
• Tattoo or acupuncture with unclean needles or instruments
• Shared needles during drug use
• Shared personal items (such as toothbrushes, razors, and nail clippers) with an infected person

The hepatitis B virus can be passed to an infant during childbirth if the mother is infected.

Risk factors for hepatitis B infection include:

• Being born, or having parents who were born in regions with high infection rates (including Asia, Africa, and the Caribbean)
• Being infected with HIV
• Being on hemodialysis
• Having multiple sex partners
• Men having sex with men

Most of the damage from the hepatitis B virus occurs because of the way the body responds to the infection. When the body's immune system detects the infection, it sends out special cells to fight it off. However, these disease-fighting cells can lead to liver inflammation.