Hepatitis B: Cause

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Cause

Hepatitis B is a liver disease caused by infection with the hepatitis B virus (HBV). Hepatitis B is one of the most common forms of viral hepatitis, which includes hepatitis A, B, C, D, and E. But hepatitis has many other causes, including some medicines, long-term alcohol use, fatty deposits in the liver, and exposure to certain industrial chemicals.

How HBV is spread

HBV is spread when blood, semen, or vaginal fluids (including menstrual blood) from an infected person enter another person's body, usually in one of the following ways:

• Sexual contact. The hepatitis B virus can enter the body through a break in the lining of the rectum, vagina, urethra, or mouth. Sexual contact is the most important risk factor for the spread of HBV in North America.
• Sharing needles. People who share needles and other equipment (such as cotton, spoons, and water) used for injecting illegal drugs may inject HBV-infected blood into their veins.
• Work-related exposure. People who handle blood or instruments used to draw blood may become infected with the virus. Health care workers are at risk of becoming infected with the virus if they are accidentally stuck with a used needle or other sharp instrument contaminated with an infected person's blood. Infection also can occur if blood splashes onto an exposed surface, such as the eyes, mouth, or a cut in the skin.
• Childbirth. A newborn baby can get the virus from his or her mother during delivery when the baby comes in contact with the mother's body fluids in the birth canal (perinatal transmission). But breast-feeding does not transmit the virus from a woman with HBV to her child.
• Body piercings and tattoos. HBV may be spread when needles used for body piercing or tattooing are not properly cleaned (sterilized) and HBV-infected blood enters a person's skin.
• Toiletries. Grooming items such as razors and toothbrushes can spread HBV if they carry blood from a person who is infected with the virus.

In the past, blood transfusions were a common means of spreading HBV. Organ transplants could also spread the disease. Today, all donated blood and organs in the United States are screened for the virus, so it is extremely unlikely that you could become infected with the virus from a blood transfusion or organ transplant.

Contagious and incubation periods

Symptoms appear an average of 60 to 90 days (although they can appear 45 to 180 days) after you have contact with the hepatitis B virus (incubation period). Blood, semen, and vaginal fluids (including menstrual blood), whether fresh or dried, are highly contagious (HBV can be easily spread) during this period and for several weeks after the onset of symptoms.

• Blood contains the highest quantities of the hepatitis B virus.
• Blood and other body fluids that contain the virus can remain contagious for at least a week and possibly much longer, even if they are dried.

If you have a short-term HBV (acute) infection, you usually cannot spread the virus after antibodies against the surface antigen of HBV appear. This generally takes several weeks. If you have a long-term (chronic) HBV infection, you are able to spread the virus as long as you have an active infection.

Last updated:	October 15, 2007
Author:	Maria G. Essig, MS, ELS
Reviewed By:	Kathleen Romito, MD - Family Medicine, W. Thomas London, MD - Hepatology
Editors:	Susan Van Houten, RN, BSN, MBA, Pat Truman, MATC