Entamoeba histolytica Antibody

Does this test have other names?

Amebiasis antibody test

What is this test?

This blood test tells your doctor whether you have antibodies in your blood to the parasite Entamoeba histolytica. This parasite causes the disease amebiasis. If you have been infected with E. histolytica, your immune system may make these antibodies. Your immune system makes proteins called antibodies to attack foreign invaders like this parasite. 

Why do I need this test?

You may need this test if you have symptoms of amebiasis. Amebiasis occurs when the parasite E. histolytica gets into your digestive system after you eat food or drink water contaminated with the parasite or put anything in your mouth that has been contaminated.

In most cases this parasite can be found by looking for it in a stool sample under a microscope. If you have symptoms of amebiasis but the parasite has not been found in your stool sample, or your doctor thinks the parasite may have spread outside your digestive system, you may need this test. Amebiasis is more common in tropical countries that have poor sanitation. If you have lived or traveled in a place that has poor sanitation, your doctor may suspect amebiasis if you have these symptoms:

• Diarrhea

• Stomachache

• Belly cramps

• Blood in your stool

• Fever 

What other tests might I have along with this test?

You may have one or more stool samples tested to look for E. histolytica. 

What do my test results mean?

Many things may affect the results of a lab test, These include the method the laboratory uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.

If antibodies to E. histolytica are found, they are measured in units called titers. This is what your test results may mean:

• A titer less than 1:32 means you probably do not have amebiasis.

• A titer greater than 1:128 may mean an active or recent amebiasis infection.

• A titer between 1:256 and 1:2048 likely means a current and active amebiasis infection. 

How is this test done?

The test requires a blood sample, which is drawn through a needle from a vein in your arm.

Does this test pose any risks?

Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, and a sense of lightheadedness. When the needle is put in your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be sore. 

What might affect my test results?

Once you develop antibodies to E. histolytica, they may stay in your blood even after you no longer have amebiasis. Because of this, in some cases a positive antibody test may only mean you have been exposed to the parasite in the past, not that you have a current infection.

How do I get ready for this test?

You don't need to prepare for this test.