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HBV: What is Acute Hepatitis B?

Christine M. Kukka
HBV Project Manager;

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When you are exposed to the hepatitis B virus (HBV), there are two types of infections that can result - acute (short-lived) or chronic (long-term).

After you are exposed to the virus, a one- to six-month incubation period may pass before you develop a hepatitis B infection. It takes that long for the virus to multiply and infect your liver. But you may be among the 70 percent of people who have had acute hepatitis B and never experienced any symptoms.

The 30 percent who do develop symptoms may experience fatigue, flu-like malaise, loss of appetite, nausea, and abdominal pain over the region of the liver. Jaundice (yellowing of the skin and eyes) can accompany these symptoms.

A very small number of people (about 0.5 percent) with acute hepatitis B may develop liver failure, which is called fulminant hepatitis. About 80 percent of people with fulminant hepatitis die within days to weeks.

If your immune system is strong, your body will eliminate or clear the virus within a few weeks of when symptoms first appeared, and you will recover fully from acute hepatitis B. To overcome the infection, your immune system will do two things. It will produce antibodies to vanquish each of the three antigens or foreign proteins that make up the hepatitis B virus. These antigens are the surface antigen (which covers the outer layer of the virus), the core antigen, and the "e" antigen. Once your body has made enough antibodies to subdue each of these antigens, you are considered cured.

Your immune system will also unleash special cells to kill the liver cells infected with the virus. This two-fold immune response eradicates the virus and viral antigens floating around in your body and bloodstream, and clears the infec-tion in your liver. The stronger the immune response, the greater your chance of eliminating the virus and recovering.

A weak immune response, which fails to eradicate all the antigens and the infection in your liver, can lead to a chronic hepatitis B. Chronic hepatitis B infection occurs in 90 percent of infants, 30 percent of children between the ages of one and 5, and six percent of persons older than age five who are infected with HBV. Young children are especially vulnerable because their immune systems do not effectively fight the virus. Adults with weak immune systems can also develop chronic hepatitis B.

To find out if you have acute or chronic hepatitis B, a blood sample will be taken from you and analyzed for the three antigens and their antibodies. If you have the hepatitis B surface antigen in your blood for more than six months, you are considered to be chronically infected.

Here is the sequence of the hepatitis B antigens and antibodies that appear (and disappear) in your blood during an acute hepatitis B infection.

1. You are infected with HBV through exposure to HBV-contaminated blood or body fluids.

2. Hepatitis B Surface Antigen (HBsAg) appears in your blood. This antigen is the first antigen or viral marker that appears in a blood test after you are infected. In acute hepatitis B it usually disappears about one to two months after it first appears.

3. Hepatitis B "e" Antigen (HBeAg) appears. This antigen is secreted by HBV-infected liver cells. This antigen appears for only for a short time, about the same time that the surface antigen appears, during an acute infection. It disappears once the immune system has defeated the viral infection in the liver.

4. Hepatitis B Core Antibody (Anti-HBc) appears. The core antibody is usually detected within one to two weeks of the appearance of hepatitis B surface antigen. The core antigen is only found in the liver, so it never shows up in a blood test. But the core antibody does appear in your blood sample. Only people who have been infected with HBV have core antibodies in their blood. People who are immunized against hepatitis B will not have core antibodies; they will only have surface antibodies because the hepatitis B vaccine contains only the surface antigen.

5. Hepatitis B Surface Antibody (Anti-HBs) appears. When surface antibodies appear in your blood test, they herald your recovery from a hepatitis B infection. Both surface antibodies and core antibodies will remain indefinitely in your blood after you clear the infection. Surface antibodies are found in the blood of those who have been vaccinated, as well as in the blood of those who have been infected and recovered from hepatitis B.

When you have acute hepatitis B, your doctor may test your blood for a certain liver enzyme (alanine aminotransferase or ALT) that is released by liver cells when they are damaged or die. When this enzyme is present at high levels in your blood, it means that liver damage is occurring as your immune system targets and kills infected liver cells.

Until you have cleared the virus and produced the surface antibody, your doctor will monitor your liver's health by testing your blood for liver enzymes and other compounds. Acute hepatitis B usually subsides two to three weeks after symptoms appear, and the liver usually returns to normal within 16 weeks.

Sexual contact with a person who has acute or chronic hepatitis B should be avoided. Condoms, if used consistently and properly, may also reduce transmission through sexual contact. However, hepatitis B immunization provides the best protection against the virus.

For more information about the hepatitis B immunization, visit the following websites.

Centers for Disease Control and Prevention website on hepatitis B immunization: http://www.cdc.gov/ncidod/diseases

Immunization Action Coalition provides extensive information on all childhood immunizations, including hepatitis B.

National Network for Immunization Safety provides up-to-date, science-based information about immunization.

American Academy of Pediatrics, an organization of 57,000 pediatricians, issues recommendations to ensure childhood health and safety.

For more information about the hepatitis B, visit the following websites.

Hepatitis B Foundation:


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