An ova and parasites exam is a relatively routine examination that people with severe diarrhea might undergo if they are admitted to a hospital. As the name suggests, the test checks for the presence of parasites and their eggs.

Parasitic infections are relatively rare in the United States, but it is possible to contract them.

A parasitic infection can cause diarrhea, cramping, and other intestinal symptoms.

A healthcare professional may wish to test for parasites if they suspect that a person may have come into contact with them. An ova and parasites exam provides them with a way to confirm or rule out the presence of parasites in a person’s stool.

This article reviews what an ova and parasites test is, who needs it, and more.

A specimen vial for an ova and parasites testShare on Pinterest

An ova and parasites test is a relatively common exam that checks for the presence of parasites and their eggs in a person’s stool.

Healthcare professionals often order it as part of diagnostic testing when a person gets admitted to the hospital for severe diarrhea.

An ova and parasites exam requires a collection of fecal samples from a person.

A person needs to collect a sample directly from a bedpan, plastic container, or another clean collecting device. The specimen cannot come from the toilet and should not be mixed with urine.

The healthcare professional will send the specimen to a lab for testing. The Centers for Disease Control and Prevention (CDC) recommend that a person collect three or more samples on different days to send for testing.

Once the lab sends back the results, the healthcare professional will review them with the person within a few days.

Severe diarrhea is a relatively prevalent health issue in the U.S.

About 90% of all costs associated with the illness occur due to five viral or bacterial pathogens:

Parasitic infection accounts for only 5% of cases of severe diarrhea in hospitalized people.

The small number of reported parasitic cases has caused some experts to question the need to continue including ova and parasite testing as a first-line test in cases of severe diarrhea.

According to recent research, the Infectious Diseases Society of America recommends that people only undergo ova and parasites testing if:

  • they present with risk factors for parasitic infection
  • they have had diarrhea for more than 7 days
  • testing can take place within 3 days of hospitalization

The American Family Physician shares similar recommendations, noting that healthcare professionals should not order the test when a person has had less than 7 days of diarrhea and does not have risk factors such as immunodeficiency or living in or traveling to an area with parasites.

Even when diarrhea has lasted 7 or more days, the organization recommends first starting with molecular or antigen testing. If the results come back negative, then they suggest a healthcare professional order an ova and parasites exam to rule out parasites.

In some cases, a healthcare professional may recommend or order an ova and parasites test if a person shows symptoms of parasitic infection and has reason to suspect one, such as a known outbreak in the area or recent travel to certain areas.

The symptoms of a parasitic infection include:

These symptoms are nonspecific, so a healthcare professional may not immediately suspect a parasitic cause. As a result, they will likely order additional testing to rule out other possible causes.

An ova and parasites exam is noninvasive, and the results usually come back quickly.

If the person is already in the hospital, they will receive either a bedpan or another collection device to collect their stool directly. Hospital staff will take care of storing the specimen and shipping it to the lab.

If the person is at home, a healthcare professional’s office may provide them with the necessary collection equipment, such as gloves, vials, and a collecting container.

The person will then need to pass a bowel movement and collect a portion of the stool to place in the provided container.

Collection kits will vary, so a person will need to follow the instructions that come with the kit to ensure that they get a usable sample.

Once they have collected the sample, the person will need to send it to the specified lab. Some labs may recommend collecting three different samples on alternating days.

How to take a stool sample

A healthcare professional will likely have the person avoid taking certain medications for 7–10 days prior to the collection of stool. Medications that a person will likely need to avoid include barium and bismuth products.

If a person is taking any antimicrobial agents, they will need to wait about 2–3 weeks before collecting a sample.

A person should follow these steps to collect a sample:

  • Wear latex gloves.
  • Get a collection container ready, such as a bedpan, a large open container, or another clean device.
  • Pass a bowel movement into the container, being careful not to urinate on the specimen or drop it into the toilet.
  • Follow the instructions on the provided kit to collect a portion of the stool and place it into the container.
  • Send the container or containers to the lab.

Different labs may have different processes, but in most cases, they will provide the results directly to the person or the healthcare professional.

The results can take a few days to come back. Once the results are available, a person can review them with the healthcare professional.

The test looks for the presence of parasites or their eggs. If either is present, the test will show this, and the healthcare professional will make treatment recommendations based on the results.

Urine and other foreign bodies can affect the test and prevent the lab from providing results. In such cases, a healthcare professional may reorder the testing.

There are three main types of parasites that affect humans: protozoa, helminths, and ectoparasites.

Protozoa and helminths are worm-like parasites that can live inside the intestines.

Protozoa can also reproduce in the body. An ova and parasites test can detect the presence of these parasites or their eggs in a person’s stool.

Ectoparasites are blood-sucking insects, such as ticks or mosquitoes. The ova and parasites test does not check for these types of parasites.

The ova and parasites test often looks for parasites such as:

If any of these parasites are present in the body, they or their eggs will be in the person’s stool.

Treatments for intestinal parasites vary depending on which parasite is present.

For example, if Giardia is the cause, a healthcare professional may prescribe metronidazole (Flagyl), tinidazole (Tindamax), or nitazoxanide (Alinia) for an infection that is severe or does not clear on its own within a few days.

If tapeworms are the cause, a healthcare professional may prescribe praziquantel (Biltricide), albendazole (Albenza), or Alinia for the initial infection.

However, they may need to prescribe additional medication if the infection has worsened or is affecting areas of the body outside the intestines. Examples include anti-seizure medication, anti-inflammatories, surgery, and shunts to drain fluid from the brain.

A healthcare professional will work with the person to determine the severity of the infection and what treatments will be most effective for them.

Although the rate of parasitic infections in the U.S. is generally low, it is still possible for a person to contract one.

This usually occurs through eating or drinking contaminated foods or drinks.

Some precautions that a person can take include:

  • avoiding swimming in lakes, streams, or rivers that might contain sewage
  • washing the hands thoroughly when working with livestock or animals or after gardening
  • drinking only bottled water and avoiding unwashed fruits and vegetables in potentially contaminated areas

An ova and parasites exam is a test that looks for the presence of intestinal parasites and their eggs.

It can help a healthcare professional determine the cause of gastrointestinal symptoms, such as diarrhea, and provide appropriate treatment.

Although parasites are generally rare in the U.S., it is possible to come into contact with some through gardening, working with livestock, or consuming contaminated foods or drinks.

If a healthcare professional suspects a parasitic infection, they will likely order an ova and parasites exam to determine the cause. They may also order other tests alongside it.