Clinician reference tool — not medical advice. This is a clinical decision-aid intended for healthcare professionals: it gives deterministic suggestions to think with, not a diagnosis or a prescription. If you’re a patient, you’re welcome to look around — but please review anything here with your own doctor; it isn’t a substitute for personalized medical care.
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Stool ova and parasites (O&P)

GI / immune · specimen: stool

Indicated in specific situations

Also called: stool O&P, ova and parasites test, parasite stool test, enteric parasite microscopy, stool parasitology, molecular parasite panel, stool parasite PCR

Chart note

Pick Ordered or Not ordered to see the note.

Indicated when

  • Persistent diarrhea (generally more than 1-2 weeks), especially with a relevant exposure: recent travel to an endemic area, new immigration or refugee status, daycare attendance or contact, exposure to untreated well water, or an outbreak setting
  • Eosinophilia, or diarrhea in an immunocompromised patient or a patient with HIV, since PHO's own parasitology requisition specifically asks practitioners to note these factors
  • Persistent unexplained GI symptoms in a patient with a prior parasitic infection history

Not indicated when

  • Routine or 'wellness panel' stool testing for parasites in an asymptomatic patient with no relevant exposure history
  • Chronic fatigue or nonspecific symptoms without GI symptoms or a relevant exposure history

Why not

Ordering O&P testing outside a relevant exposure or symptom picture has a low pre-test probability of a true positive in most of Ontario, and daily variation in parasite shedding means a single negative specimen does not reliably rule out infection when clinical suspicion is genuinely high; Public Health Ontario's own kit instructions recommend collecting one or two additional specimens over one to two weeks to improve detection when infection is still suspected after an initial negative [2].

Better first step

Take a travel, immigration, daycare/contact, and water-source history before ordering O&P testing, and order it specifically when that history or the symptom picture (persistent diarrhea, eosinophilia) supports it, using PHO's collection protocol or a community/hospital lab equivalent.

Typical ND rationale

An ND may order stool O&P testing, or a molecular (PCR) parasite panel, in a patient with persistent GI symptoms or fatigue, reasoning that an undiagnosed parasitic infection is a real and sometimes overlooked cause of chronic symptoms, particularly with any travel or exposure history.

Where the ND is right

This is a place the ND is often right: parasitic infection is a genuine, testable, and treatable cause of persistent GI symptoms, particularly with a travel, immigration, daycare, or well-water exposure history, and testing in that context is appropriate, not an overreach. The caveat is limiting testing to patients with a relevant symptom or exposure, and, when suspicion is high, collecting more than one specimen rather than relying on a single negative result.

Ontario coverage & CONO orderability

OHIP status
insured
Listed by name in the 2026 Schedule of Benefits for Laboratory Services: L650 'Parasites and ova - faeces concentration' (fee $9.12) and L654 'Parasites and ova, smear only, special stain(s)' (fee $9.12). Insured when ordered by a physician, midwife, or NP who has clinically assessed the patient; the same test ordered by a naturopathic doctor is not an insured service and is billed privately (Reg. 552 s.22(1); SOB-LS 2026 preamble). Public Health Ontario also performs enteric parasite microscopy directly for requesting health care providers, separately from the community-lab Schedule [2]. A molecular (PCR) parasite panel was not separately confirmed as a listed, insured item in this session.
CONO orderable
Yes — CONO list #140
CONO 140 'Parasites and Ova', stool specimen.

Linked conditions

Counselling script

“With travel, recent immigration, daycare contact or well water, and ongoing gut symptoms, a stool test for parasites is reasonable. Parasites don't show up in every sample, so if the first test is negative and I'm still concerned, we may repeat it once or twice. Without a symptom or an exposure, it isn't needed.”

Revisit if

  • Diarrhea or GI symptoms persist despite a negative initial test and suspicion remains
  • New relevant exposure or travel history

References

  1. [1]Ontario Ministry of Health (2026). Ontario Health Insurance Plan: Schedule of Benefits for Laboratory Services (effective April 1, 2026). linkStool O&P (L650, L654) is listed by name and insured in the 2026 Schedule of Benefits for Laboratory Services
  2. [2]Public Health Ontario (2026). Enteric Parasite Microscopy (Kit and Test Ordering Instructions). linkPHO performs enteric parasite microscopy directly; collection protocol calls for one or two additional specimens over 1-2 weeks to increase detection given variable daily shedding
  3. [3]Ontario Ministry of Health (2026). Ontario Health Insurance Plan: Schedule of Benefits for Laboratory Services (effective April 1, 2026). linkCommunity lab tests are insured only when ordered under the Schedule by an authorized prescriber
  4. [4]Government of Ontario (e-Laws) (2026). Health Insurance Act, R.R.O. 1990, Reg. 552: General, s. 22 (insured laboratory services). linkInsured lab testing requires ordering by an authorized provider who has clinically assessed the patient
  5. [5]Ontario Ministry of Health (2026). Ontario Health Insurance Plan: Schedule of Benefits for Laboratory Services (effective April 1, 2026). linkTests ordered by anyone other than an authorized provider, including NDs, are not insured services
Evidence notes

The exposure-based indications (travel, immigration/refugee status, daycare contact, well water, eosinophilia, HIV/immunocompromise) are drawn from PHO's parasitology kit-ordering page content, which was fetched successfully, and from a web-search description of PHO's requisition fields; PHO's 'Parasite - Bowel' Test Information Index page itself (which likely states a formal indications list, similar in structure to the H pylori serology page) returned the site's generic A-Z navigation shell rather than page-specific content when fetched, and could not be rendered as readable text within this session's fetch budget, so the specific indications list here is a reasonable synthesis rather than a verbatim-quoted PHO indications statement, and is flagged accordingly. Molecular/PCR parasite panels (e.g. for Cryptosporidium, Cyclospora, Dientamoeba, Entamoeba, Giardia) exist at PHO as a distinct enteric protozoa PCR test separate from O&P microscopy; this was not fully researched as its own record in this session and is only mentioned as an alias here.