Quickly detect intestinal parasites

Identify infection in patients who have traveled to parasite-endemic regions

The ova and parasite test (Mayo ID: OPE) is a fundamental laboratory method performed to detect parasitic helminths and protozoa in stool specimens. While not the preferred test for detecting common causes of parasitic diarrhea in the United States and Canada (e.g., Giardia, Cryptosporidium), it can be useful for cases of intestinal parasitic infection in individuals with a travel history to parasite-endemic regions.

Artificial intelligence

The traditional OPE test employs microscopic examination of wet and stained stool preparations. Recently, advances in digital microbiology and artificial intelligence (AI) have allowed for stained stool preparations to be screened by well-designed and validated AI algorithms to improve the sensitivity and speed of parasite detection.

Mayo Clinic has collaborated with Techcyte to leverage AI to detect protozoan parasites in concentrated stool specimens stained with a modified trichrome stain. This AI algorithm serves as a useful tool for our skilled technologists and guides their final interpretation of the specimen.

Advantages of the Mayo Clinic Laboratories approach

  • Faster turnaround times.
  • Increased sensitivity for parasite detection.
  • Decreased risk of human error and ergonomic issues.
  • Preferred single-vial collection system (compared to the two-vial PVA/10% formalin combo system) is easier to ship, store, and label. It is also easier for patients to self-collect their own specimen properly.
  • Single-vial collection system has simpler disposal requirements for expired or improperly collected vials (contain alcohol vs. heavy metal).

By the numbers


of all OPE exams are negative, reflecting the fact that most OPE exams are not clinically indicated. Refer to our testing guidance and algorithms to learn if the test is right for your patient.

Key testing

OPE | Ova and Parasite, Travel History or Immunocompromised, Feces

  • Detects and identifies parasitic protozoa and the eggs and larvae of parasitic helminths observed within stool specimens.

OAPNS | Ova and Parasite, Microscopy, Varies

  • Detects and identifies parasitic protozoa and the eggs and larvae of parasitic helminths observed within non-stool specimens (e.g., bile, bone marrow, CSF, abscess material, colonic washings, and duodenal aspirates).

Use of Artificial Intelligence and Digital Slide Scanning for Detection of Intestinal Protozoa in Trichrome-Stained Stool Specimens

In this "Hot Topic," Bobbi Pritt, M.D., describes the challenges to traditional microscopy for the detection of protozoa in stool specimens, lists potential uses of artificial intelligence in parasite detection, and discusses workflow modifications that may be needed when implementing digital slide scanning and AI-assisted interpretation.

Appropriate approach to OPE testing

OPE testing is not part of the recommended approach for patients with diarrhea unless the patient has traveled to an area where parasitic helminths are present. Instead, molecular amplification or antigen detection methods are recommended for detecting the most common causes of parasitic diarrhea (e.g., Giardia, Cryptosporidium, Cyclospora).

The following algorithms will help guide test ordering for patients with infectious causes of diarrhea:

Laboratory testing for infectious causes of diarrhea

This algorithm considers all causes of infectious diarrhea, including bacteria and viruses. Most cases of infectious diarrhea are self-limited and the patient will resolve without treatment. Therefore, testing is not recommended unless symptoms have occurred for more than seven days, or the patient has risk factors or warning signs for severe disease. When testing is indicated, we recommend the gastrointestinal pathogens panel (Mayo ID: GIP), as it provides the most efficient, rapid, and cost-effective approach for detecting parasites, viruses, and bacteria that cause diarrhea.

Parasitic investigation of stool specimens algorithm

This algorithm specifically addresses the evaluation of patients with a suspected parasitic infection. Patients with diarrhea may be candidates for the gastrointestinal panel described below. Direction is also given for identifying macroscopic worms, including tapeworm proglottids.

Learn how to order these evaluations at your institution.