Lab Test

Ova and Parasite Antigen Screen

Diarrhea, Stool, Giardia, Cryptosporidium, O&P, O and P

Test Codes





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

Specimen Collection Criteria

Collect (Preferred): Preserved stool specimen in EcoFix transport medium.

Also acceptable: Preserved stool specimen in SAF, Cary-Blair or Para-Pak transport medium. 
Stool specimen in a sterile collection container with no preservative.

Physician Office/Draw Specimen Preparation

Unpreserved specimens must be refrigerated immediately after collection.

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.

Preparation for Courier Transport


  • Preserved specimens (SAF, EcoFix, or Cary-Blair): 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.
  • Stool specimens that have been concentrated or treated with PVA, Protofix, or MIF fixatives.
  • SAF, EcoFix, or Cary-Blair transport received >1 week from collection date.
  • Fresh, unpreserved stool specimens not refrigerated and/or older than 48 hours from time of collection.
  • Stool aspirates or endoscopic procedures


Specimen Stability for Testing:

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

Specimen Storage in Department Prior to Disposal:

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


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

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


Monday – Friday. 
Results available within 24-48 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

Aids in the detection and diagnosis of Giardia and/or Cryptosporidium gastrointestinal infection in patients with gastrointestinal symptoms.

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).

Cryptosporidiosis is caused by Cryptosporidium spp., a coccidian protozoan. Cryptosporidiosis is a parasitic infection of medical and veterinary importance. The parasite infects the epithelial cells of the GI, biliary and respiratory tracts of man as well as other vertebrates, including poultry and other birds, fish, reptiles, small mammals (rodents, cats, dogs) and large mammals (particularly cattle and sheep). The major symptom in human patients is diarrhea, that may be profuse and watery, preceded by anorexia and vomiting in children. The diarrhea is associated with cramping abdominal pain. General malaise, fever, anorexia, nausea, and vomiting occur less often. Infection may be asymptomatic. Symptoms usually wax and wane, but remit in 15 to 30 days in most immunologically healthy persons. Immunodeficient persons, especially persons with AIDS, may be unable to clear the parasite and the disease has a prolonged and fulminant clinical course (losing 3-6 liters of fluid/day), contributing to death. Symptoms of cholecystitis may occur in biliary tract infections; the relationship between respiratory tract infections and clinical symptoms is unclear.


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 (1).

Cryptosporidium oocysts have been identified in human fecal specimens from more than 50 countries on six continents. In developed areas such as the United States and Europe, the prevalence of infection ranges from less than 1% to 4.5% of individuals tested. In developing regions, the prevalence is significantly higher, ranging from 3% to 20%. Children over 2 years of age, animal handlers, travelers, and close personal contacts of infected individuals (families, health care and day-care workers) are at increased risk of infection (2).

Incubation Period

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

Cryptosporidium: Not precisely known; 1 to 12 days is the likely range, with an average of about 7 days (2).


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

Cryptosporidium: Fecal-oral, with person-to-person, animal-to-person, and waterborne transmission are all important. Oocysts, the infectious stage, appear in the stool at the onset of symptoms and continue to be excreted in the stool for several weeks after symptoms resolve; outside the body, they may remain infective for 2-6 months in a moist environment (2).


  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. Chin,J. (editor) Control of Communicable Diseases Manual, American Public Health Association, Washington, DC, 2021, 20th ed.
  3. Xiao, L., and Cama, V. 2011. Cryptosporidium. In: Versalovic, J., eds., Manual of Clinical Microbiology, 10th Edition. American Society for Microbiology Press, Washington, D.C.
  4. Garcia, L.S. 2001. Intestinal Protozoa: Flagellates and Coliates. Diagnostic Medical Parasitology, 4th edition. ASM Press. Washington, D.C., pp. 36-59.
  5. Garcia, L.S. 2010. Cryptosporidium parvuum. In: Garcia, L.S. (ed.) Diagnostic Medical Parasitology. ASM Press. Washington, D.C. 3rd edition.

CPT Codes

87328 and 87329.


Last Updated


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