Hepatitis B is a serious infection of the liver. It's caused by the hepatitis B virus. It can be mild and short-term. Or it may be long-term and lead to chronic liver disease and liver failure in infants and young children.

The hepatitis B virus is spread from person to person through blood and body fluids, such as blood, semen, vaginal secretions, or saliva. Infants may also get the disease if they are born to someone who has the virus. Infected children often spread the virus to other children if there is frequent contact. People who are likely to be exposed to hepatitis B are:

• Babies born to those who have hepatitis B
• Babies born to those who have come from a country where hepatitis B is widespread, such as Southeast Asia and China
• People in long-term care
• People who live with someone with the virus
• People who need kidney dialysis
• People who use I.V. drugs, have many sex partners, or have unprotected sex

About one-third of people with hepatitis B in the U.S. have an unknown source.

The younger the person, the greater the likelihood of staying infected with hepatitis B and having lifelong liver problems. These can include scarring of the liver and liver cancer.

Children with hepatitis B may not have symptoms. Symptoms of acute infection include:

• Yellowing of the skin and eyes (jaundice)
• Fatigue
• Loss of appetite
• Nausea, vomiting, or abdominal (belly) pain
• Low-grade fever
• Rash and diffuse itching
• Joint pain

Your child's doctor will take a history and perform a physical exam. Tests that may be needed include:

• Blood tests. These will evaluate the liver function and test for infections that cause hepatitis.
• Ultrasound. This test uses sound waves to look at the liver and surrounding tissues.
• Liver biopsy. In cases of chronic infection, a liver biopsy may be necessary.

Hepatitis B symptoms can usually be treated with medicine. Patients with uncomplicated cases can expect to recover completely. Patients with chronic hepatitis B are treated with medicine to reduce the activity of the virus and prevent liver failure.

Chronic hepatitis B patients should stay away from anything that can further injure the liver, such as alcohol, certain medicines, dietary supplements, and herbs. Discuss these substances with your child's doctor.

In rare cases where the liver damage caused by hepatitis B is life-threatening, a liver transplant may be needed.

The hepatitis B vaccine is widely used for routine childhood immunization. The vaccine prevents hepatitis B infection. It's given as 3 or 4 shots. Follow the vaccine schedule advised by your child's doctor. A baby born to someone who has hepatitis B is also given a shot of immune globulin. This contains antibodies to lower the chance that the baby will get hepatitis B.