The Disease

Hepatitis B is a disease that affects the liver. It is one of several hepatitis diseases (for example, hepatitis A and hepatitis C). These are caused by different germs, but are similar in that they all affect the liver ("hepatitis" comes from the Greek words for "liver" and "inflammation").

Hepatitis B is caused by a virus. Some people who are infected with the hepatitis B virus never feel sick. Others have symptoms that might last for several weeks. Those symptoms can include:

• loss of appetite and tiredness,
  
• pains in muscles, joints or stomach,
  
• diarrhea or vomiting,
  
• yellow skin or eyes (jaundice).
  

This is called "acute" hepatitis B.

Some people never recover from hepatitis B. They develop what is called "chronic" (long-term) hepatitis B virus infection. They might not look or feel sick, but they will probably carry the hepatitis B virus in their blood for the rest of their lives, and they can infect other people.

Many of these chronically infected people will suffer from serious health problems, such as cirrhosis (scarring of the liver) or liver cancer. In fact, the hepatitis B virus causes most of the liver cancer in the world. In the United States alone, there are more than 1 million people chronically infected with the hepatitis B virus. In 1996, an estimated 200,000 people became infected with hepatitis B virus, and about 4,000 to 5,000 people a year die from hepatitis B.

Hepatitis B virus is spread through contact with the blood, or other body fluids, of an infected person. People can get hepatitis B by having unprotected sex, by sharing drug needles, or by sharing personal items like razors or toothbrushes with someone who is infected. Doctors, nurses, and other health care workers can get hepatitis B through exposure to blood from infected patients. Police, fire fighters, and paramedics who are exposed to blood are also at risk.

Why, then, do we immunize children against hepatitis B when they don't have sex, don't take drugs, and are not nurses or police officers? One important reason is that babies can get infected too. If a mother is chronically infected with hepatitis B, her baby could become infected during birth. If these babies are not immunized immediately, most of them will become chronically infected too. One out of 4 of these babies will eventually die from cirrhosis or liver cancer. Also, children can be infected through exposure to blood, saliva, or other fluids from infected children or adults. While this is not common, vaccination is a reasonable precaution, particularly since the vaccine is a very safe one.

U.S. DEPARTMENT OF HEALTH & HUMAN SERVICES
Centers for Disease Control and Prevention
National Center for Immunization and Respiratory Diseases