Questions & Answers

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What causes hepatitis B?
Hepatitis B is a liver disease caused by the hepatitis B virus (HBV).

How does HBV spread?
The spread of HBV occurs when blood from an HBV-infected person enters the body of a person who is not infected. This can occur through having sex with an HBV-infected person without using a condom (the efficacy of latex condoms in preventing infection with HBV is unknown, but their proper use may reduce spread of HBV).

Sex contact is the most common reason for the spread of HBV infection in the United States. The spread of HBV from male to female or female to male accounts for about 1 out of 3 acute (recently acquired) HBV infections in adults. The risk of spreading HBV increases if the male or female has multiple sex partners, a history of a sexually transmitted disease, or has sex with an HBV-infected person. About 1 out of 4 acute HBV infections occur among men who have sex with men.

HBV is also easily spread by sharing drugs, needles, or "works" when "shooting" drugs. The risk of HBV infection from HBV-contaminated needlesticks is much greater than the risk of spreading HIV by this method. In the United States, illegal drug use injection accounts for about 16 out of 100 acute HBV infections. Other types of percutaneous (through the skin) exposures, including tattooing and body piercing, have also been reported to result in the spread of HBV when good infection control practices have not been used. Unsafe injections in medical settings are a major source of HBV spread in many developing countries and might be a risk for United States residents traveling abroad, if medical care is required in settings that have poor infection control practices.

HBV is also spread through needlesticks or sharps exposures on the job and from an infected mother to her baby during birth. Breastfeeding has not been associated with the spread of HBV.

HBV can also be spread during childhood. Most early childhood spread occurs in households of people with chronic (life-long) HBV infection, but the spread of HBV has also been seen in daycare centers and schools. The most likely way that the spread of HBV occurs during early childhood involves contact between an infected person's body fluids (e.g., their blood or drainage from their wounds or skin lesions) and breaks in the child's skin. HBV can be spread also when an HBV-infected person bites another person who is not infected. HBV can be spread also by an infected person pre-chewing food for babies, and through contact with HBV from sharing personal-care items, such as razors or toothbrushes. The virus remains infectious and capable of spreading infection for at least seven days outside the body. Virus can be found on objects, even in the absence of visible blood.

HBV is not spread through food or water, sharing eating utensils, hugging, kissing, coughing, and sneezing or by casual contact, such as in an office or factory setting. People with chronic HBV infection should not be excluded from work, school, play, childcare, or other settings.

How long does it take to show signs of illness after coming in close contact with a person who has HBV infection?
The incubation period ranges from 45 to 160 days (average 120).

What are the signs and symptoms of hepatitis B?
About 7 out of 10 adults with acute hepatitis B have signs or symptoms when infected with HBV. Children under age 5 years who become infected rarely show any symptoms. Signs and symptoms of hepatitis B might include nausea, lack of appetite, tiredness, muscle, joint, or stomach pain, fever, diarrhea or vomiting, headache, dark urine, light-colored stools, and yellowing of the skin and whites of the eyes (jaundice). People who have such signs or symptoms generally feel quite ill and might need to be hospitalized. In 2006, 4,713 cases of hepatitis B were reported to the CDC and 8% of these cases died from their infection.

How serious is hepatitis B?
Hepatitis B is very serious. About 9 out of 10 infants (who do not receive appropriate prophylaxis at birth), 30 out of 100 children younger than age 5, and about 2 of 100 adults who are infected with HBV are unable to clear HBV from their bodies and become chronically infected. This serious condition is discussed below. Even though people might eventually recover from their acute infection, a feeling of tiredness and poor health might last for months.

What does it mean to have chronic HBV infection?
People with chronic HBV infection are infectious and can transmit HBV to others. Usually, chronically infected people do not feel sick and do not realize they are infected. They generally have HBV infection for their entire lives. They are also at high risk of developing chronic liver disease, including cirrhosis (scarring of the liver), liver failure, and liver cancer.

What are the complications of chronic HBV infection?
An estimated 15-25 people out of 100 with chronic HBV infection eventually develop serious liver disease. Chronic HBV infection is responsible for most HBV-related sickness and death, including cirrhosis, liver failure, and liver cancer. When people are infected at a very young age, these forms of liver disease do not appear usually until young adulthood or middle age.

Is HBV infection a serious problem in the world?
In the United States, an estimated 3,000-4,000 people die each year of HBV-related cirrhosis, and another 1,000-1,500 die each year of HBV-related liver cancer. Worldwide, the medical consequences of chronic HBV infections are a huge problem. Approximately 350 million people around the world are chronically infected with HBV and approximately 1 million of these people die each year from cirrhosis leading to liver failure or liver cancer. The medical literature states that hepatitis B is the 10^th leading cause of death worldwide.

What is the risk of getting HBV infection while traveling in other countries?
Short-term travelers to regions (Asia, Sub-Saharan Africa, Amazon Basin, Eastern Europe, and the Middle East) in which there are moderate to high rates of HBV infection are typically at risk for infection only through exposure to blood in medical, healthcare or disaster-relief activities; receipt of medical care that involves blood exposures; or sexual activity or drug use. The Centers for Disease Control and Prevention recommends hepatitis B vaccination for travel to any of these places, regardless of the length of stay.

How common is hepatitis B in the United States?
About 5 out of 100 people in the United States will contract HBV infection sometime in their lifetime, if not vaccinated. Approximately 0.8 to 1 million people have chronic HBV infection at the present time. Most of these people do not know they are infected.

During 1990-2005, the overall occurrence of reported cases of acute hepatitis B declined to a great extent. In 2006, the estimated number of new HBV infections was about 46,000--a decrease from an estimated 232,000 new infections in 1990. Racial and ethnic disparities for acute HBV infection were nearly eliminated for Asian/Pacific Islanders, American Indians/Alaska Natives, and Hispanics. However, racial disparities for acute (recently acquired) hepatitis B still remain among blacks. The highest occurrence of acute hepatitis B occurred among people ages 25-44 despite their race or ethnicity.

The overall decrease in the occurrence of acute hepatitis B in the United States is most likely due to the increased use of hepatitis B vaccine and changes in risk-reduction behaviors among at-risk populations in response to the HIV/AIDS epidemic. During 1990-2006, the greatest decline in cases was among children and adolescents, the group with the largest increase in hepatitis B vaccination coverage. Reporting of hepatitis B still remains a problem as many people do not exhibit symptoms recognized as hepatitis B and many cases/infections are missed and therefore not reported to health authorities.

Despite the dramatic decrease in the number of new HBV infections in the United States, chronic HBV infection remains a major problem. As stated above, about 1 million people have chronic HBV infection currently and most of these people do not know they are infected because they haven’t been tested. Most cases of chronic HBV infection in the U.S. are found in immigrants or refugees from areas of the world with moderate or high rates of hepatitis B. Some of these areas of the world include Asia, Africa, the Pacific Islands, and Eastern Europe. People from these areas of the world should be tested to find out if they are chronically infected.

How does a person know if s/he has HBV infection?
A blood test called IgM anti-HBc is needed to diagnose acute hepatitis B. There are additional blood tests for hepatitis B that determine other aspects of HBV infection. These other blood tests can tell whether or not a person is currently infected and whether or not a person has been infected in the past. If the tests indicate a person has been infected in the past, testing will also determine whether the person has developed protective antibodies to the virus (i.e., they have gotten over the infection and will not get infected with HBV again [this is called immunity]) or whether they still have virus in their blood, indicating they might have chronic HBV infection.

Is there a medication to treat hepatitis B?
There are several Food and Drug Administration (FDA)-approved medications that might help a person who has chronic HBV infection. These medications don't usually get rid of the virus, but they might decrease the chance of the infected person developing severe liver disease. Not everyone is a candidate for these medications. Researchers continue to seek additional cures for hepatitis B. There is no treatment (other than supportive care) for people with acute hepatitis B.

How long can a person with HBV infection spread HBV?
A person with acute or chronic HBV infection is contagious as long as they have the virus in their blood, which can only be determined by blood testing. In general, a person with acute hepatitis B gets rid of the virus in their blood in six months. If this does not happen, it is likely the person will become chronically infected with HBV for life.

What are some important Do's and Don'ts for people with chronic HBV infection?

DO's

• Cover all cuts and open sores with a bandage.
• Discard used items such as bandages and menstrual pads carefully so no one is accidentally exposed to your blood.
• Wash hands well after touching your blood or infectious body fluids.
• Clean up blood spills; then clean the area again with a bleach solution (one part household chlorine bleach to 10 parts of water).
• Tell your sex partner(s) you have hepatitis B so they can be tested and vaccinated (if not already infected or vaccinated). Partners should have their blood tested 1-2 months after three doses of vaccine are completed to be sure the vaccine worked.
• Use condoms (rubbers) during sex unless your sex partner has had hepatitis B or has been immunized and has had a blood test (as described above) demonstrating immunity to HBV infection. (Condoms might also protect you from other sexually transmitted diseases).
• Tell household members to see their doctors for testing and vaccination for hepatitis B.
• Tell your doctors that you are chronically infected with HBV.
• See your doctor every 6-12 months to check your liver for abnormalities, including cancer.
• If you are pregnant, tell your doctor that you have HBV infection. It is critical that your baby is started on hepatitis B shots within a few hours of birth.

DON'Ts

• Don’t share chewing gum, toothbrushes, razors, washcloths, needles for ear or body piercing, or anything that might have come in contact with your blood or infectious body fluids.
• Don’t pre-chew food for babies.
• Don’t share syringes and needles.
• Don’t donate blood, plasma, body organs, tissue, or sperm.

What should you do if you have been exposed to HBV?
If you think you've been exposed to HBV, don't delay. Contact your doctor or clinic. If you have not been vaccinated, it is recommended that you receive treatment with hepatitis B immune globulin (HBIG). This is a blood product containing protective HBV antibodies. You should also get the first dose of hepatitis B vaccine as soon as possible, preferably at the same time as the HBIG is given, but at a different site on your body. Following this, you will need to complete the full hepatitis B vaccine series (usually a total of three doses over a six-month period).

Can you get hepatitis B more than once?
No. If you get an acute case of hepatitis B and recover, you should have protective antibodies in your blood that will prevent any further infection with HBV. The medical literature does report possible mutant strains of HBV infection, but these are rare and would be highly unlikely to occur.

How does HBV differ from hepatitis A virus (HAV) and hepatitis C virus (HCV)?
HBV, HCV, and HAV are different viruses that attack and injure the liver, and can cause similar symptoms Usually people get HAV infection from close personal contact with an infected person or from ingesting fecally-contaminated food or water. HBV and HCV are spread when an infected person's blood or blood contaminated body fluids enter another person's bloodstream. HBV and HCV infections can cause chronic liver problems. HAV does not. There are vaccines that will protect people from HAV infection and HBV infection. Currently, there is no vaccine to protect people from HCV infection. There are medications that are approved by the FDA for treatment of chronic HBV and HCV infections. If a person has had one type of viral hepatitis in the past, it is still possible to get the other types.

Click here to view frequently asked questions about the hepatitis A virus. To view frequently asked questions about the hepatitis C virus from the CDC, click here.

Questions and answers about hepatitis B vaccine

This page was reviewed on May 5, 2008