Practical Science

Frequently Asked Questions


If you have any questions that are still left unanswered after browsing through the following frequently asked questions
please feel free to contact me.


1) How many specimens should be collected for an Ova and Parasite examination?

Initially only one specimen should be submitted for examination. Research has proven that 90% of the parasites, if they are present at all will be recovered from the first specimen. The OAML (The Ontario Association of Medical Laboratories) has released a guideline in November 1998 outlining this important issue. If a negative result is obtained (NPS) from the first specimen and the patient is still symptomatic, a second set of specimens may be warranted.

2) Is there any food or medication that should be avoided prior to collecting a stool sample for Ova and Parasite examination?

For a period of 1 - 3 weeks (depending on the substance) (59)prior to collecting a stool sample the patient should avoid any medicines (consult your physician) containing laxatives, antidiarrhoeal drugs, mineral oil, barium, magnesium and antimicrobials.

3) How should I collect the specimen and what is a good stool specimen?

The stool should be collected in a clean dry container. Try to avoid contaminating the stool with urine. An easy way to obtain a stool sample is to stretch some plastic wrap across the toilet bowl. This way, stool about the size of a cherry can be transferred to the specimen vial containing SAF (a preservative). Try to sample areas containing blood, mucus or watery areas of the stool.

4) What parasites are pathogenic (disease causing)? Is treatment available?

The intestinal protozoa, Balantidium coli, Entamoeba histolytica, Dientamoeba fragilis, Giardia lamblia and the controversial Blastocystis hominis are considered pathogenic. All helminths (worms) are considered pathogens. Treatment is available and may be determined by consulting The Sanford Guide To Antimicrobial Therapy.

5) What is the significance of nonpathogenic amoeba?

If you have been diagnosed with a nonpathogenic parasite and are symptomatic (sick), your illness is probably caused by another organism such as a pathogenic parasite, a bacterium, virus or other noninfectious disease. Further testing arranged by your physician should be considered. If you are asymptomatic (not sick) the amoeba present will cause no harm and in most cases are self limiting and will remain in the body for weeks to years.

6) Do nonpathogenic amoeba require treatment?

Treatment is not required as these organisms in most cases are self limiting and cause no harm.

7) What can be done to avoid being infected by a parasite?

Practicing better hygiene will certainly help eliminate infection or reinfection. When traveling you should make yourself aware of the parasites endemic (common) in that area. This may mean drinking only boiled or treated bottled water, eating only fully cooked food or avoiding an area altogether.

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David M. Raymondo
MLT, CLS(m)
Professional Affiliation: Gamma-Dynacare Medical Laboratories, Ottawa, Ontario, Canada
Gamma-Dynacare is a Division of the Dynacare Health Group