Ova and Parasite Stool
Also Known As: O&P stool test, stool test for ova and parasite, fecal smear, stool sample examination, parasitic examination (stool), 3 specimen stool test, O and P with permanent stain, triple feces test (TFT).
What Is The Ova And Parasite Test?
It is a microscopic examination of a sample of stool to detect parasites, ova (eggs of parasite), or cysts (a form of parasite covered with resistant capsule). Parasites are the living organisms that live on or within other living organisms (host) and get their nutrition from the host. They range from single cellular protozoans to multicellular worms (helminths).
Parasites are common in countries that have poor sanitation. They affect your digestive tract by invading your body through contaminated food and water with the ova of the parasite. The food may seem completely normal in looks, smell, and taste. But once they enter your digestive tract, you may become infected and shed them in your stool. Without proper sanitation techniques, you may spread this infection to others.
A wide variety of parasites affect the digestive tract of humans. The most common include Giardia lamblia, Entamoeba histolytic, and Cryptosporidium. Besides these, a wide range of worms also infects your gastrointestinal tract. Each parasite has its life cycle, maturation phases, the number of hosts; some may reside in an intermediate host (sheep, cow, etc.) before infecting humans. You may get parasites by touching contaminated soil, eating undercooked or raw meat, swimming in contaminated water, changing diapers of children who are infected with parasites. They usually affect children, elders, those with impaired immunity like HIV/AIDS patients, and patients on immunosuppressive drugs, etc.
What Is The Test Used For?
Ova and parasite test is used to diagnose digestive tract diseases caused by parasites. This test determines whether a parasite or its eggs are present in your body or not. Parasites, their ova, and cysts are shed in stool. A stool sample is taken for that purpose; a slide is prepared and observed under a microscope to detect ova (egg), cyst, or parasite. Ova are rigid structures that can exist outside the host for a long time and remain infectious. Different parasites and cysts have different shapes, sizes, and internal structures characteristic of that species.
This test can detect not all parasites; only those which live in the digestive tract and whose eggs are passed in stool can be identified. Other methods are used for other parasites like malaria and pinworm (which mostly affect children and cause rectal itching).
Examples of parasites that the O and P test can identify are:
- Entamoeba histolytic
- Giardia lamblia
- Roundworms like Ascaris, strongyloid
- Tapeworms like tinea solium, diphyllobothrium latum
- Flatworms like liver flukes
Why And When Do You Need Ova And Parasite Test?
Your health care provider may order this test if you have signs and symptoms of prolonged gastrointestinal disease or a history of consuming contaminated food and water or traveling to parasitic endemic areas. These symptoms and signs include:
- Prolong diarrhea which lasts for more than a few days
- Bloody diarrhea
- Mucus in stool
- Abdominal pain and cramping
- Nausea and vomiting
- Weight loss
- Pallor and lethargy (a sign of blood loss anemia)
- Headache and fever
- Greasy stool that floats
- Itchy rectum
If the illness washes away in a few days or it remains uncomplicated, your health care provider may not order testing. However, suppose the symptoms worsen, and complications begin, like persistent or severe diarrhea that causes dehydration and electrolyte imbalance, bloody diarrhea, and mucus in stool. In that case, ova and parasite test may be ordered. Other tests may also be conducted for further evaluation and diagnosis, such as stool culture and antigen tests to identify microbe.
What Kind Of Sample Is Required?
A fresh stool sample of 10ml or 10gm is required to collect in a laboratory-provided container. The sample should not be contaminated with toilet water, urine, or toilet paper and transported to the laboratory within 2 hours of collecting the sample or transported into the special vial containing a preservative. Delay in transportation to the laboratory; make it harder to find parasite in the sample as the structure of the parasite deteriorates in the unpreserved stool. If it cannot reach the laboratory, the sample should be refrigerated.
It is recommended to collect multiple samples on different days (mostly on alternate days) and times because parasites and ova are shed periodically and may not be present in stool all the time. That’s why at least 3 samples are required to make a definitive diagnosis. Multiple samples increase the chances of detecting parasites.
Do You Need To Prepare For The Test?
No special preparation is required for this test. But certain medications can interfere with the test results, so the collection of the specimen should be delayed for 7-10 days in case of bismuth, magnesia, castor oil, and barium intake, 2 -3 weeks for antimicrobial drug use, and 3 weeks for gallbladder dye use after the procedure.
Is There Any Risk To This Test?
There is no known risk related to ova and parasite tests. The laboratory needs only a small amount of stool for the test, so there is no discomfort.
What Does The Test Result Mean?
The results are usually obtained between 2 -4 days and are usually reported as negative and positive.
A negative result means you don’t have a parasitic infection, or the sample does not have enough parasites or eggs to be detected. Your health care provider may retest or order a new test for diagnosis.
A positive test means you have a parasitic infection; results also define the type and the number of parasites present in the sample. Usually, a single parasite is responsible for your symptoms, but there could be more than one. Your healthcare provider may start your treatment after this report.
Should you have any questions regarding your test results, you must consult your healthcare provider.
Related Tests: Stool culture, Stool antigen test, GI pathogen penal test, Colonoscopy, Tissue transglutaminase test
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