The Giardia lamblia parasite is one of the chief causes of diarrhea in the United States. It lives in the gastrointestinal (GI) system and passes from the body in stool (feces).
In a Giardia antigen test, a stool sample is checked for the presence of Giardia.
The Giardia antigen test is used to make a diagnosis of giardiasis, the digestive tract illness caused by Giardia lamblia. A doctor may order the test if your child has symptoms such as watery diarrhea, abdominal pain, large amounts of intestinal gas, appetite loss, and nausea or vomiting, especially if there's been an outbreak of giardiasis at your child's school or daycare center, your child recently drank untreated water, or if your family recently visited a developing country. The test also may be used to determine if treatment for giardiasis has been effective.
The test may be ordered by itself or in combination with an ova and parasite exam (a microscopic evaluation of stool for the presence of parasites). The antigen test is more sensitive in detecting Giardia lamblia than the ova and parasite (O&P) exam, but it can't identify any other organisms or conditions that cause gastrointestinal distress.
Unlike most other lab tests, a stool sample is often collected by parents at home, not by health care professionals at a hospital or clinic.
If possible, your child may be asked to avoid certain foods and treatments for 2 weeks before the test, including:
The doctor or hospital laboratory will usually provide written instructions on how to collect a stool sample. If instructions aren't provided, here are tips for collecting a stool sample from your child:
After the sample arrives at the laboratory, a technician puts a stool sample in contact with a chemical that changes color in the presence of products of the Giardia lamblia parasite. It's important to remember that the Gardia antigen test detects the presence of only that specific parasite, so the doctor may order additional tests to reach a definitive diagnosis.
In general, the result of the Giardia antigen test is reported within a day.
No risks are associated with collecting stool samples.
Collecting a stool sample is painless. Tell your child that collecting the stool won't hurt, but it has to be done carefully. A child who's old enough might be able to collect the sample alone to avoid embarrassment. Tell your child how to do this properly.
If you have questions about the Giardia antigen test, speak with your doctor.
Reviewed by: Steven Dowshen, MD
Date reviewed: September 2014
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|Centers for Disease Control and Prevention (CDC) The CDC (the national public health institute of the United States) promotes health and quality of life by preventing and controlling disease, injury, and disability.|
|American Academy of Pediatrics (AAP) The AAP is committed to the health and well-being of infants, adolescents, and young adults. The website offers news articles and tips on health for families.|
|Lab Tests Online This non-commercial site was developed by laboratory professionals to educate caregivers, patients, and patients' families about lab tests.|
|Giardiasis Giardiasis, one of the chief causes of diarrhea in the United States, is an intestinal illness caused by a microscopic parasite.|
|Diarrhea Most kids battle diarrhea from time to time, so it's important to know what to do to relieve and even prevent it.|
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|Stool Test: Fecal Blood Stool samples can provide information about a problem in the GI system. To test the stool for the presence of blood, a noninvasive test - the fecal occult blood test (FOBT) - is performed.|
|Stool Test: H. Pylori Antigen A doctor may request an H. pylori antigen stool test if your child has symptoms that indicate a peptic ulcer, such as indigestion, abdominal pain, a full or bloated feeling, nausea, frequent belching, or vomiting.|
|Stool Test: Ova and Parasites (O&P) This exam may be done if your child has diarrhea for an extended period, blood or mucus in the stool, abdominal pain, nausea, headaches, or fever.|
|Stool Tests Your child's doctor may order a stool collection test to check for blood, bacteria, ova, or parasites. Find out how this test is performed and when you can expect the results.|
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