At a glance

Also known as

HAV

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

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 function 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.  Hepatitis A IgM antibodies develop early in the course of infection. The presence of hepatitis A IgM antibodies suggests acute hepatitis A but is only diagnostic if taken in the right clinical context. A positive hepatitis A IgM together with the presence of grossly abnormal liver function tests demonstrating hepatitis, the presence of symptoms such as nausea, fever, malaise, abdominal discomfort or a history of significant contact with a confirmed case is consistent with acute Hepatitis A. A positive Hepatitis A IgM is also seen in patients who have received the Hepatitis A vaccine in the days or weeks prior to testing and therefore the result should not be interpreted as evidence of acute disease. Testing for immunity to Hepatitis A can also be performed. Acute hepatitis is also caused by a number of other infectious and non-infectious agents and the choice of tests to use depends on the clinical scenario.

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.

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, an 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 antibody test can be repeated to see if you have responded to the vaccine.

What does the test result mean?

Looking for reference ranges?

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 for further interpretation of results.

 

HAV IgM Total HAV antibody (IgM and IgG) Results indicate
Positive   Acute HAV infection or recent Hepatitis A vaccination
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; no immunity to Hepatitis A; vaccine may be recommended if at risk

Is there anything else I should know?

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

Common Questions

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’.

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.

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.

Last Review Date: June 3, 2013