Share this page
Print this article
Was this page helpful?

Hepatitis A virus

Also known as: HAV
Formal name: Viral hepatitis A antibody
Related tests: Hepatitis B, hepatitis C

At a Glance

Why Get Tested?

To diagnose an infection with hepatitis A or to evaluate the need for, or the response to, hepatitis A vaccination

When to Get Tested?

If you have symptoms of an infection with or have been exposed to the hepatitis A virus

Sample Required?

A blood sample drawn from a vein in your arm

The Test Sample

What is being tested?

Hepatitis A antibody is produced in response to an infection with the hepatitis A virus. Hepatitis A is a highly contagious liver infection caused by the hepatitis A virus (HAV). It is one of several various causes of hepatitis, a condition characterised by inflammation and enlargement of the liver. Hepatitis A is one of five "hepatitis viruses" identified so far, including B, C, D, and E that are known to cause the disease.

Hepatitis A is spread through food or water contaminated with the virus or by coming in contact with an infected person. While hepatitis A can cause a severe, acute disease, it does not cause a chronic infection as do some of the other hepatitis viruses. If you are exposed to hepatitis A, your immune system produces antibodies in response to the virus. This test detects hepatitis A antibodies in the blood.

While hepatitis has many different causes, the signs and the symptoms are the same. In hepatitis, the liver is damaged and unable to function normally. It cannot process toxins or waste products such as bilirubin for their removal from the body. During the course of the disease, bilirubin and liver enzyme levels in the blood can increase. While tests such as bilirubin or a liver funstion tests can tell your doctor that you have hepatitis, they will not tell s/he what is causing it. Antibody tests for hepatitis viruses may help determine the cause.

If you are exposed to hepatitis A, your body will first produce hepatitis A IgM antibodies. These antibodies typically develop 2 to 3 weeks after first being infected and persist for about 2 to 6 months. Hepatitis A IgG antibodies are produced within 1 to 2 weeks of the IgM antibodies and usually persist for life. Because hepatitis A IgM antibodies develop early in the course of infection, a positive hepatitis A IgM test is usually considered diagnostic for acute hepatitis A. A total hepatitis A antibody test detects the presence of the IgM and IgG antibodies and may help determine if you have been infected in the past and have some immunity to the disease. A test for hepatitis A IgM may be part of an acute viral hepatitis panel that may be used to determine which virus is causing symptoms when viral hepatitis is suspected.

How is the sample collected for testing?

A blood sample is taken by needle from a vein in the arm.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

The Test

How is it used?

There are two versions of the test but both detect antibodies. Antibodies are produced by the body to protect itself from antigens (foreign proteins).

  • Hepatitis A IgM (immunoglobulin M) is the first antibody produced by the body when it is exposed to a virus and is used for early detection of infection. IgM antibodies to HAV are used in a patient with evidence of acute hepatitis, such as jaundice, dark urine, pale coloured stools, fever and loss of appetite.
  • Hepatitis A IgG (immunoglobulin G) antibodies develop later and remain present for many years, protecting the person against further infection by the same virus. Testing for IgG antibodies is used for long-term monitoring. A total antibody test (which detects both IgM and IgG antibodies) detects both current and previous infection with the hepatitis A virus.

    • ^ Back to top

    When is it requested?

    Testing for the presence of IgM antibodies to hepatitis A is done if you have the symptoms or are likely to have been exposed to the virus. If you are being considered for the HAV vaccine, a total antibody test may be requested before you are given the vaccine to see if you need it (if the antibodies are already present, the vaccine won’t help you). Once you have completed the two doses of the vaccine, the total HAV antibody test can also be used to see if you have responded to the vaccine.

    ^ Back to top

    What does the test result mean?

    Looking for reference ranges?

    If the test result is positive (or reactive) and you have not been given the HAV vaccine, you have had a hepatitis A infection – even if you were not aware of it. About 30% of adults over age 40 have antibodies to HAV. If you have been given the vaccine, a positive result means you are immune to HAV and cannot be infected by it. See the table below.

     

    HAV IgM Total HAV antibody (IgM and IgG) Results indicate
    Positive   Acute HAV infection
    Negative Positive No active infection, but previous HAV exposure; has developed immunity to HAV
      Positive Has been exposed to HAV but does not rule out acute infection
      Negative No current or previous HAV infection; vaccine may be recommended if at risk

    ^ Back to top

    Is there anything else I should know?

    It is presumed that one infection with hepatitis A produces lasting immunity against further infections.

    ^ Back to top

    Common Questions

    1.  How could I have been infected with the virus without knowing it?

    The virus is found in faeces and contaminated water. You may have eaten raw fruit or vegetables handled by an infected person who did not wash their hands properly or you may have eaten raw or improperly cooked seafood that had fed in contaminated waters. Children are often infected by HAV and either do not become sick or have very mild symptoms such as fever and diarrhoea and are often thought to have ‘flu’.

    ^ Back to top

    2.  If I have hepatitis A how long will I be contagious?

    You can spread the disease to others from the time you are first infected up until symptoms begin to appear which can be about 4 weeks. Generally adults are contagious for 2 weeks after contracting the disease. Children and people who are immunocompromised may be contagious for up to 6 months.

    ^ Back to top

    3.  Is there any way to prevent the disease?

    Yes. There is a vaccine available. It is recommended for people travelling to specific countries, and for those who have damage to their liver from some other cause.

    ^ Back to top

    Ask a Laboratory Scientist

    * indicates a required field!




      Patient, Family member or Friend
      Healthcare Professional
      Other



    You must provide a valid email address in order to receive a response.




    Spam Prevention

    | |

    Article Sources

    « Return to Related Pages

    NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.