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Giardia Antigen (Stool)

Does this test have other names?

Giardia antigen (feces)

What is this test?

This is a stool sample test to look for the parasite Giardia intestinalis, which causes an infection of the small bowel called giardiasis. It may also be a cause of travelers' diarrhea. Symptoms include diarrhea, nausea, vomiting, belly (abdominal) cramps, dehydration, and vague feelings of discomfort. Giardiasis is common in daycare centers and among people who travel internationally.

Parasites like Giardia usually have a life cycle in which they pass through several different forms.

Why do I need this test?

You might need this test if you have unexplained diarrhea or other symptoms listed above, and your medical history suggests that you may have this infection.

What other tests might I have along with this test?

You may also have a white blood cell count done to check for infection and tests to look for other microorganisms in your stool.

What do my test results mean?

Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are abnormal, you may not have a problem. To learn what the results mean for you, talk with your healthcare provider.

If the lab detects the parasite in your stool sample, most likely you have giardiasis. But Giardia may not be present in the first sample. More than one sample may be needed for an accurate diagnosis.

How is this test done?

This test requires a stool sample. You may be asked to provide more than one sample. Your healthcare provider will tell you how to collect a sample in a disposable specimen container with a lid. Don't collect stool from the toilet bowl or put toilet paper into the specimen container.

Does this test pose any risks?

This test has no known risks.

What might affect my test results?

Barium, anti-diarrhea medicine, antacids, and mineral oil can interfere with this test. Antibiotic treatment can also affect the test results.

How do I get ready for this test?

You don't need to prepare for this test.

Medical Reviewers:

  • Greco, Frank, MD
  • Holloway, Beth Greenblatt, RN, M.Ed.