Does this test have other names?

Amebiasis antibody test

What is this test?

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

Why do I need this test?

You may need this test if you have symptoms of amebiasis. Amebiasis happens when the parasite E. histolytica gets into your digestive system. That may happen 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 healthcare provider thinks the parasite may have spread outside your digestive system, you may need the antibody test. In most cases, Entamoeba infections don't cause symptoms. 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 healthcare provider may suspect amebiasis if you have these symptoms:

• Watery or bloody diarrhea

• Stomachache

• Belly cramps

• Fever

• Weight loss

What other tests might I have along with this test?

You may have 1 or more stool samples tested to look for E. histolytica.

What do my test results mean?

Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you. 

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 is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand. 

Does this test pose any risks?

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting 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. Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use.