Ova and Parasite Test

An ova and parasite test looks for intestinal parasites and their eggs (ova) by checking a sample of your stool (poop) under a microscope. The test is also called an O&P. Intestinal parasites are tiny life forms that can live and reproduce in your digestive system.

They most commonly infect your intestines (the long, tube-shaped organ in your belly that helps digest food). A parasitic infection can cause diarrhea, gas, stomach cramps, and other abdominal (belly) symptoms. When people and animals have intestinal parasites, eggs and parasites are found in their stool.

Tiny amounts of contaminated stool that you can't see, smell, or taste can get into water, soil, food, and beverages. If a person with an infection doesn't wash their hands well after using the bathroom, parasites can also get on any surfaces that they touch. If you swallow parasites or their eggs in contaminated water or food, you can develop an infection.

You can also become infected if you put anything in your mouth that has touched contaminated surfaces. There are many types of intestinal parasites. The most common types in the U.S. include: Giardia; Cryptosporidium; Entamoeba histolytica, which causes a disease called 'amebiasis.' In the US, amebiasis happens mostly in people who have been in countries where it is common.

This includes tropical areas with poor sanitary conditions.; These parasites are often found in water, including rivers, lakes, ponds, and streams. They are also found in swimming pools, hot tubs, and drinking water. That's because certain types of intestinal parasites are not easily killed by chlorine in water.

Other intestinal parasites that aren't common in the U.S. include many types of worms, such as pinworms. These parasites also spread through contaminated soil, water, food, and drink. But some of them, such as hookworms, can infect you by getting into your skin, especially if you walk barefoot on contaminated ground or other surfaces.

Healthy people often recover from intestinal parasite infections without treatment. When treatment is needed, it usually works to get rid of the parasites. But intestinal parasites can cause severe, long-lasting diarrhea and other serious conditions in people with weakened immune systems.

This includes people with HIV, cancer, certain genetic disorders, and people who take certain medicines that affect their immune systems. Infants and older adults also have weaker immune systems.

Why this test is done

Your provider may order an O&P test if you have symptoms that could be caused by an intestinal parasite, and the symptoms have lasted for a few days. They include:

• Diarrhea
• Abdominal pain
• Blood and/or mucus in the stool
• Unusually foul-smelly, greasy stools that float
• Nausea and vomiting
• Gas
• Fever
• Weight loss

Sometimes these symptoms go away without treatment, so testing is not always needed. Your provider will be more likely to order a test for parasites if:

• You have developed serious symptoms, including an electrolyte imbalance or dehydration.
• You have a weakened immune system because of disease, medicines you take, or your age. Older adults and very young children often have weaker immune systems.
• You could have been exposed to parasites. This includes:
• Drinking or accidentally swallowing water from a stream and/or lake.
• Traveling to another country where intestinal parasites are more common.
• Being around another person who has an intestinal parasite infection.

How to prepare

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

Sample type

Stool

Other names for this test

parasitic examination (stool), stool sample exam, stool O&P, fecal smear, egg cyst