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. The parasite causes an infection of the small bowel called giardiasis. It may also be a cause of travelers' diarrhea. Symptoms include:

• Diarrhea

• Foul-smelling, fatty stools

• Bloating, excessive gas (flatus)

• Nausea

• Vomiting

• Belly (abdominal) cramps

• Dehydration

• Weakness, fatigue

Giardiasis is common in daycare centers and among people who travel to different countries. It can also be transmitted by contaminated water and food.

Parasites like Giardia usually have a life cycle in which they pass through several different forms. Because of this, they may not be detected right away. You may need to have this test more than once.

Why do I need this test?

You might need this test if you have unexplained diarrhea or other symptoms listed above, and your healthcare provider thinks 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 test. This is done to check for infection. You may also have other tests to look for other germs in your stool.

What do my test results mean?

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

If the lab detects the parasite in your stool sample, most likely you have giardiasis. But  Giardia may not be 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. You will do it with a disposable specimen container with a lid. Don't collect stool from the toilet bowl or put toilet paper into the specimen container or pee into it.

Does this test pose any risks?

This test has no known risks.

What might affect my test results?

Barium, antidiarrhea 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. 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.