Lab Test

Antigen, Giardia

Giardia Antigen, Giardia Ag, Giardia Specific Antigen Detection

Test Codes

Antrim #41981, EPIC: LAB5465, SOFT: AGGRD




At least 2 weeks should elapse following barium administration before collection of the specimen.

Specimen Collection Criteria

Collect: Random stool specimens in SAF, EcoFix or 10% Formalin (for routine Ova and Parasite examination), Cary-Blair or Para-Pak transport medium.

Also acceptable: Random stool specimen in a sterile collection container with no preservative.

Physician Office/Draw Specimen Preparation

Maintain preserved specimens at room temperature (20-26°C or 68-78.8°F) or refrigerated (2-8°C or 36-46°F) prior to transport. Unpreserved specimens must be refrigerated immediately after collection. 

Preparation for Courier Transport


  • Preserved specimens (SAF, EcoFix, 10% Formalin, Cary-Blair or Para-Pak) at room temperature (20-26°C or 68-78.8°F) or refrigerated (2-8°C or 36-46°F).
  • Unpreserved specimens, refrigerated (2-8°C or 36-46°F).

Rejection Criteria

  • More than one specimen per patient collected within a 24 hour period.
  • Stool collected following a soap suds enema.
  • Frozen specimens.
  • Stool specimens that have been concentrated or treated with PVA, Protofix, or MIF fixatives.
  • Para-Pak or Cary-Blair transport cannot be older than 1 week from the date of collection.
  • Fresh, untreated stool specimens not refrigerated and/or older than 48 hours from time of collection. These samples are unacceptable for routine Ova and Parasite examination.


Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 2 hours (Unpreserved)
Room Temperature (20-25°C or 68-77°F): 7 days (Preserved)
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable 

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days


Dearborn Microbiology Laboratory
Taylor, Trenton and Wayne sent to Dearborn Microbiology Laboratory for testing.

Royal Oak Microbiology Laboratory
Farmington Hills, Grosse Pointe and Troy sent to Royal Oak Microbiology Laboratory for testing.


Monday – Friday.
Results available within 24 hours.

Reference Range


Test Methodology

Immunochromatographic Assay.


A single diagnostic assay should not be used as the only basis for forming a clinical diagnosis. Results should be correlated with patient symptoms and the overall clinical picture.

Clinical Utility

This assay aids in the detection of Giardia Specific Antigen (GSA 65) in aqueous extracts of fecal specimens.

Clinical Disease

In acute giardiasis, symptoms include nausea, upper intestinal cramping or pain, and malaise. There is often explosive, watery diarrhea characterized by foul-smelling stools. These symptoms are accompanied by flatulence and abdominal distention. The acute stage of clinical giardiasis may be followed by a chronic stage, or the chronic type of infection may be the first indication of infection. In such infections, there are flatulence, mushy foul-smelling stools, upper intestinal cramping, and abdominal distention. A number of patients also exhibit belching, nausea, anorexia, vomiting, and symptoms of heartburn. Fever and chills may be present but to a lesser degree. Symptoms may mimic peptic ulcer or gallbladder disease (1).


Giardiasis is an important human intestinal disease in most areas of the world. Outbreaks related to contaminated water are common in the United States, and infections are frequent in day-care centers and among campers and male homosexuals (1).

Incubation Period

The incubation period is variable, ranging from 12-20 days.


Giardiasis is acquired by ingestion of the cysts of G.lamblia (1).


  1. Leber, A. L., and Novak-Weekley, S. M. 2011. Intestinal and Urogenital Amebae, Flagellates and Ciliates.. In: Versalovic, J. et. al. (eds.).Manual of Clinical Microbiology. 10th edition. ASM Press. Washington, D.C.
  2. Garcia, L.S. 2001. Intestinal Protozoa: Flagellates and Coliates. Diagnostic Medical Parasitology, 4th edition. ASM Press. Washington, D.C., pp. 36-59.

CPT Codes

LOINC:  6412-1


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