Back to Test Compendium

Stool Full Ova and Parasites (O and P) Exam - Provincial

Discipline

Microbiology

Overview

Description

  • Gastrointestinal parasitic infections can be a burden in patients’ health. Many of gastrointestinal parasites can cause malabsorption and some can do tissue invasions. While acute severe illness rarely happens, chronic infection can significantly impact the patient if untreated.

Ordering Recommendations

  • Instruct patient to defecate into a clean bowl. Collect stool without contaminating with urine
  • Microbiology Requisition
    • If relevant clinical history is NOT provided, a Giardia/Cryptosporidium screen will be done instead of the O&P test
    • All specimens submitted to RRPL that meet the requirements for the O&P examination will be tested for Cryptosporidium
    • Wait 7 days before collecting stool specimen if the patient has received antibiotics, mineral oil, bismuth, kaolin, barium swallows or enemas
    • Tests for intestinal parasites should NOT be requested for IN patients who have been hospitalized for longer than 3 days
    • Microsporidia test requests will be referred out and will take 10 working days for the results

Specimen Information

Specimen types accepted

  • Stool

Specimen collection container

  • Stool SAF

Collection procedure

  • Instruct patient to defecate into a clean bowl.  Collect stool without contaminating with urine. Immediately add stool (a grape sized amount of solid specimen or to fill line if a liquid specimen) to SAF preservative and mix thoroughly using spoon provided. Screw lid on tightly.  Record collection date and time on each specimen and requisition
    • Stool specimens collected in SAF preservative may be refrigerated at (2 - 8°C) or stored at room temperature (20 - 25°C)
    • Submit a series of three stool specimens. Collect stools at 2 - 3 day intervals. Submit one stool per collection date, do NOT pool the specimens. If multiple stools with the same collection date are submitted, only one will be tested.

Transport and stability

  • Stable at room temperature due to preservative

Performance

Methodology

RRPL
  • Microscopy and antigen detection of crypto and giardia
  • Full microscopy for amoeba and helminths in patients with identified risk factors (i.e. travel to endemic areas and appropriate symptoms)
RUH
  • Multiplex PCR for detection of Cryptosporidium, Giardia and Entamoeba histolytica
  • Full microscopy for amoeba and helminths in patients with identified risk factors (i.e. travel to endemic areas and appropriate symptoms)

Days/times performed

Testing sites

RRPL
  • Monday to Friday
  • 0800-1700
RUH
  • Monday to Sunday
  • 0800-1600

Maximum laboratory time

RRPL
  • Negative: 14 days
  • Positive: 14 days of the time of receipt at RRPL
RUH
  • 7-21 days after receipt in the laboratory

Specimen retention time

  • Specimen retained by lab for 1 month

Other information

Relevant history is required for an Ova and Parasite Exam.  The Microbiology requisition lists the following as relevant:

  • Travel/immigration outside Canada or U.S. within the last 2 years (state when and where)
  • Prior Parasite
  • Immunosuppressed
  • Suspected helminth infection (other than Enterobius vermicularis), i.e. visualization of a worm in stool
  • Eosinophilia
  • Age <13 years
  • Symptoms >2 weeks
  • Unsafe food/water
  • Case contact
  • Other (must provide reason)

NB:  Diarrhea is NOT adequate history for performing an O&P examination.

Last Updated: October 22, 2025