Cryptosporidium & Giardia Antigens by EIA




Test Mnemonic

OVAPSC

Primary CPT Codes

  • 87328 - QTY (1), Immunoassay, Cryptosporidium
  • 87329 - QTY (1), Immunoassay, Giardia

LOINC ®

48059-0

Aliases

  • Stool EIA
  • Stool test
  • STUL kit
  • Stool kit
  • Cryptosporidium Antigen
  • Cryptosporidium EIA
  • Giardia Antigen
  • Giardia EIA

Includes

  • Confirmation of all Cryptosporidium positive EIA, by microscopy with a modified acid-fast stain (CRYSPO). Additional charges for reflex testing apply.

Performing Laboratory

Cleveland Clinic Laboratories


Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
Complete to fill lineStoolC/S/Cary BlairRefrigeratedRefrigeratedC&S/Cairy Blair and Ecofix available in a STUL kit; submit stool using a STUL kit at refrigerated conditions. STUL kit can be purchased via oracle #1570140. Refer to Stool collection guide (https://clevelandcliniclabs.com/our-laboratories/laboratory-medicine/microbiology/plmi-collection-guidelines-resources/stool-specimen-collection-guide/). An Ecofix fixative is needed to confirm any Cryptosporidium antigen positive by microscopy.

Alternate Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
10 mLStoolSterile containerRefrigeratedRefrigeratedUnpreserved stool should be submitted to the lab in a securely tightened sterile screw-top container and should be limited to inpatient settings due to a significantly shorter stability window. Use of non-standard (eg. food containers) is discouraged. Refer to Stool collection guide (https://clevelandcliniclabs.com/our-laboratories/laboratory-medicine/microbiology/plmi-collection-guidelines-resources/stool-specimen-collection-guide/)

Minimum Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
5 mL     

Stability

Environmental Condition Description
AmbientPreserved: 2 weeks Unpreserved: Preferred within 6 hours. Acceptable within 12 hours.
RefrigeratedPreserved: 2 weeks Unpreserved: Preferred within 6 hours. Acceptable within 12 hours.
FrozenPreserved: 2 months Unpreserved: Unacceptable

Days Performed

Mon - Fri

Turnaround Time

1 - 3 days

Methodology

Name Description
Enzyme Immunoassay (EIA) 

Special Info

Recommend sending a complete STUL kit for submission of all outpatient specimens.

Clinical Info

Cryptosporidium and Giardia are the most common causes of parasitic intestinal disease. Acute disease is characterized by watery diarrhea, abdominal cramps etc. Cryptosporidium has also been implicated in several waterborne outbreaks. Chronic or asymptomatic infections can also occur. Prevalence of these parasites can vary among geographic areas and populations. A higher prevalence is seen in children and immunosuppressed population.

Clinical Limitation

Giardia and Cryptosporidium are common causes of diarrhea in the U.S. Antigen tests are 80–90% sensitive with a single stool sample, but false negatives may occur with low organism burden, persistent symptoms, or recent antiparasitic use. In such cases, paired testing with microscopic examination of multiple stool specimens may aid diagnosis​. Rapid antigen tests for Giardia and Cryptosporidium may yield false-positive results due to cross-reactivity or nonspecific binding. Additionally, antigen shedding may persist for some time after symptoms have resolved, potentially leading to positive results even after effective treatment. Therefore, microscopy with appropriate staining techniques is recommended to confirm positive results, particularly in asymptomatic individuals or when clinical suspicion is low. Interfering substances include barium, bismuth, metamucil, castor oil, mineral oil, or antiamoebic drugs within one week prior to specimen collection can give false negative results. Excessively bloody and mucoid samples can yield false positive results.

Reflex Tests

The following additional test(s) may be ordered depending on results: