URL of this page: https://medlineplus.gov/lab-tests/ova-and-parasite-test/

Ova and Parasite Test

What is an ova and parasite test?

An ova and parasite test looks for parasites and their eggs (ova) in a sample of your stool. A parasite is a tiny plant or animal that gets nutrients by living off another creature. Parasites can live in your digestive system and cause illness. These are known as intestinal parasites. Intestinal parasites affect tens of millions of people around the world. They are more common in countries where sanitation is poor, but millions of people in the United States get infected every year.

The most common types of parasites in the U.S. include giardia and cryptosporidium, often referred to as crypto. These parasites are commonly found in:

  • Rivers, lakes, and streams, even in those that appear clean
  • Swimming pools and hot tubs
  • Surfaces such as bathroom handles and faucets, diaper changing tables, and toys. These surfaces may contain traces of stool from an infected person.
  • Food
  • Soil

Many people get infected with an intestinal parasite when they accidentally swallow contaminated water or take a drink from a lake or stream. Children at day care centers are also at higher risk for infection. Children may pick up the parasite by touching an infected surface and putting their fingers in their mouths.

Fortunately, most parasite infections go away on their own or are easily treated. But a parasite infection can cause serious complications in people with weakened immune systems. Your immune system may be weakened by HIV/AIDS, cancer, or other disorders. Infants and older adults also have weaker immune systems.

Other names: parasitic examination (stool), stool sample exam, stool O&P, fecal smear

What is it used for?

An ova and parasite test is used to find out if parasites are infecting your digestive system. If you've already been diagnosed with a parasite infection, the test may be used to see if your treatment is working.

Why do I need an ova and parasite test?

Your health care provider may order tests if you or your child has symptoms of an intestinal parasite. These include:

Sometimes these symptoms go away without treatment, and testing is not needed. But testing may be ordered if you or your child has symptoms of a parasite infection and are at higher risk for complications. Risk factors include:

  • Age. Infants and older adults have weaker immune systems. This can make infections more dangerous.
  • Illness. Certain illnesses such as HIV/AIDS and cancer can weaken the immune system.
  • Certain medicines. Some medical conditions are treated with drugs that suppress the immune system. This can make a parasite infection more serious.
  • Worsening symptoms. If your symptoms don't improve over time, you may need medicine or other treatment.

What happens during an ova and parasite test?

You will need to provide a sample of your stool. Your provider or your child's provider will give you specific instructions on how to collect and send in your sample. Your instructions may include the following:

  • Put on a pair of rubber or latex gloves.
  • Collect and store the stool in a special container given to you by your health care provider or a lab.
  • If you have diarrhea, you can tape a large plastic bag to the toilet seat. It may be easier to collect your stool this way. You will then put the bag into the container.
  • Make sure no urine, toilet water, or toilet paper mixes in with the sample.
  • Seal and label the container.
  • Remove the gloves, and wash your hands.
  • Return the container to your health care provider as soon as possible. Parasites may be harder to find when stool is not tested quickly enough. If you are unable to get to your provider right away, you should refrigerate your sample until you are ready deliver it.

If you need to collect a sample from a baby, you will need to:

  • Put on a pair of rubber or latex gloves.
  • Line the baby's diaper with plastic wrap
  • Position the wrap to help prevent urine and stool from mixing together.
  • Place the plastic wrapped sample in a special container given to you by your child's provider.
  • Remove the gloves, and wash your hands.
  • Return the container to the provider as soon as possible. If you are unable to get to your provider right away, you should refrigerate your sample until you are ready deliver it.

You may need to collect several stool samples from yourself or your child over a period of a few days. This is because parasites may not be detected in every sample. Multiple samples increase the chance the parasites will be found.

Will I need to do anything to prepare for the test?

You don't need any special preparations for an ova and parasite test.

Are there any risks to the test?

There is no known risk to having an ova and parasite test.

What do the results mean?

A negative result means no parasites were found. This can mean you don't have a parasite infection or there were not enough parasites to be detected. Your health care provider may retest and/or order different tests to help make a diagnosis.

A positive result means you've been infected with a parasite. The results will also show the type and number of parasites you have.

Treatment for an intestinal parasite infection almost always includes drinking plenty of fluids. This is because diarrhea and vomiting can cause dehydration (the loss of too much fluid from your body). Treatment may also include medicines that get rid of the parasites and/or relieve symptoms.

If you have questions about your results, talk to your health care provider.

Is there anything else I need to know about an ova and parasite test?

There are steps you can take to help prevent a parasite infection. They include:

  • Always wash your hands after going to the bathroom, changing a diaper, and before handling food.
  • Don't drink water from lakes, streams, or rivers, unless you know for sure it has been treated.
  • When camping or traveling to certain countries where the water supply may not be safe, avoid tap water, ice, and uncooked foods washed with tap water. Bottled water is safe.
  • If you are unsure if water is safe, boil it before drinking. Boiling water for one to three minutes will kill the parasites. Wait until the water cools before drinking.

References

  1. Centers for Disease Control and Prevention [Internet]. Atlanta: U.S. Department of Health and Human Services; Parasites - Cryptosporidium (also known as "Crypto"): General Information for the Public [cited 2019 Jun 23]; [about 5 screens]. Available from: https://www.cdc.gov/parasites/crypto/general-info.html
  2. Centers for Disease Control and Prevention [Internet]. Atlanta: U.S. Department of Health and Human Services; Parasites - Cryptosporidium (also known as "Crypto"): Prevention and Control - General Public [cited 2019 Jun 23]; [about 4 screens]. Available from: https://www.cdc.gov/parasites/crypto/gen_info/prevention-general-public.html
  3. Centers for Disease Control and Prevention [Internet]. Atlanta: U.S. Department of Health and Human Services; Parasites - Cryptosporidium (also known as "Crypto"): Treatment [cited 2019 Jun 23]; [about 4 screens]. Available from: https://www.cdc.gov/parasites/crypto/treatment.html
  4. Centers for Disease Control and Prevention [Internet]. Atlanta: U.S. Department of Health and Human Services; Parasites: Diagnosis of Parasitic Diseases [cited 2019 Jun 23]; [about 4 screens]. Available from: https://www.cdc.gov/parasites/references_resources/diagnosis.html
  5. Centers for Disease Control and Prevention [Internet]. Atlanta: U.S. Department of Health and Human Services; Parasites - Giardia: General Information [cited 2019 Jun 23]; [about 4 screens]. Available from: https://www.cdc.gov/parasites/giardia/general-info.html
  6. Centers for Disease Control and Prevention [Internet]. Atlanta: U.S. Department of Health and Human Services; Parasites - Giardia: Prevention and Control - General Public [cited 2019 Jun 23]; [about 4 screens]. Available from: https://www.cdc.gov/parasites/giardia/prevention-control-general-public.html
  7. Centers for Disease Control and Prevention [Internet]. Atlanta: U.S. Department of Health and Human Services; Parasites -Giardia: Treatment [cited 2019 Jun 23]; [about 4 screens]. Available from: https://www.cdc.gov/parasites/giardia/treatment.html
  8. CHOC Children's [Internet]. Orange (CA): CHOC Children's; c2019. Viruses, Bacteria and Parasites in the Digestive Tract [cited 2019 Jun 23]; [about 3 screens]. Available from: https://www.choc.org/programs-services/gastroenterology/viruses-bacteria-parasites-digestive-tract
  9. Kids Health from Nemours [Internet]. Jacksonville (FL): The Nemours Foundation; c1995-2019. Stool Test: Ova and Parasite (O&P) [cited 2019 Jun 23]; [about 2 screens]. Available from: https://kidshealth.org/en/parents/test-oandp.html?
  10. Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2019. Ova and Parasite Exam [updated 2019 Jun 5; cited 2019 Jun 23]; [about 2 screens]. Available from: https://labtestsonline.org/tests/ova-and-parasite-exam
  11. Mayo Clinic [Internet]. Mayo Foundation for Medical Education and Research; c1998–2019. Dehydration: Symptoms and causes; 2018 Feb 15 [cited 2019 Jun 23]; [about 3 screens]. Available from: https://www.mayoclinic.org/diseases-conditions/dehydration/symptoms-causes/syc-20354086
  12. Merck Manual Consumer Version [Internet]. Kenilworth (NJ): Merck & Co. Inc.; c2019. Cryptosporidiosis [updated 2019 May; cited 2019 Jun 23]; [about 3 screens]. Available from: https://www.merckmanuals.com/home/infections/parasitic-infections-intestinal-protozoa-and-microsporidia/cryptosporidiosis
  13. Merck Manual Consumer Version [Internet]. Kenilworth (NJ): Merck & Co. Inc.; c2019. Giardiasis [updated 2019 May; cited 2019 Jun 23]; [about 3 screens]. Available from: https://www.merckmanuals.com/home/infections/parasitic-infections-intestinal-protozoa-and-microsporidia/giardiasis
  14. Merck Manual Consumer Version [Internet]. Kenilworth (NJ): Merck & Co. Inc.; c2019. Overview of Parasitic Infections [updated 2019 May; cited 2019 Jun 23]; [about 3 screens]. Available from: https://www.merckmanuals.com/home/infections/parasitic-infections-an-overview/overview-of-parasitic-infections?query=ova%20and%20parasite%20exam
  15. UF Health: University of Florida Health [Internet]. Gainesville (FL): University of Florida Health; c2019. Stool ova and parasites exam: Overview [updated 2019 Jun 23; cited 2019 Jun 23]; [about 2 screens]. Available from: https://ufhealth.org/stool-ova-and-parasites-exam
  16. University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; c2019. Health Encyclopedia: Ova and Parasites (Stool) [cited 2019 Jun 23]; [about 2 screens]. Available from: https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=ova_and_parasites_stool
  17. UW Health [Internet]. Madison (WI): University of Wisconsin Hospitals and Clinics Authority; c2019. Health Information: Stool Analysis: How It Is Done [updated 2018 Jun 25; cited 2019 Jun 23]; [about 5 screens]. Available from: https://www.uwhealth.org/health/topic/medicaltest/stool-analysis/aa80714.html#tp16701
  18. UW Health [Internet]. Madison (WI): University of Wisconsin Hospitals and Clinics Authority; c2019. Health Information: Stool Analysis: Test Overview [updated 2018 Jun 25; cited 2019 Jun 23]; [about 2 screens]. Available from: https://www.uwhealth.org/health/topic/medicaltest/stool-analysis/aa80714.html#tp16698

The medical information provided is for informational purposes only, and is not to be used as a substitute for professional medical advice, diagnosis or treatment. Please contact your health care provider with questions you may have regarding medical conditions or the interpretation of test results.

In the event of a medical emergency, call 911 immediately.