Hepatitis B is a liver disease caused by infection with the hepatitis B virus.
How hepatitis B is spread
The virus is spread when blood, semen, or vaginal fluids (including menstrual blood) from an infected person enter another person's body. This usually happens through:
- Sexual contact. The hepatitis B virus can enter the body through a break in the lining of the rectum, vagina, urethra (the tube that carries urine out of the body), or mouth.
- Sharing needles and other equipment (such as cotton, spoons, and water) used for injecting illegal drugs.
- Work tasks. People who handle blood or instruments used to draw blood may become infected. Health care workers are at risk of infection if they are accidentally stuck with a used needle or other sharp instrument that has an infected person's blood on it. Infection also can occur if blood splashes onto an exposed surface, such as the eyes, the mouth, or a cut in the skin.
- Childbirth. A newborn baby can get the virus from his or her mother. This can happen during delivery when the baby comes in contact with the mother's body fluids in the birth canal. But breast-feeding doesn't spread the virus from a woman to her child.
- Body piercings and tattoos. The virus may be spread when needles used for body piercing or tattooing aren't sterilized and infected blood enters a person's skin.
- Toiletries. Grooming items such as razors and toothbrushes can spread the virus if they carry blood from a person who is infected.
In the past, blood transfusions were a common way of spreading hepatitis B. 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 from a blood transfusion or an organ transplant.
Contagious and incubation periods
Symptoms appear about 3 months after you have contact with the virus (incubation period). But they can appear as soon as 2 months to as late as 5 months after contact. Blood, semen, and vaginal fluids, whether fresh or dried, are highly contagious during this period and for several weeks after the start of symptoms.
If you have a short-term (acute) infection, in most cases you can't spread the virus after your body starts making a certain type of hepatitis B antibody. This generally takes several weeks. If you have a long-term (chronic) infection, you are able to spread the virus as long as you have an active infection.