How many stool samples are needed for an accurate ova and parasite test?

Most laboratories recommend collecting three separate stool samples on consecutive days, as parasite shedding can vary. Providing multiple samples increases the likelihood of detecting eggs or cysts.

What symptoms should prompt me to get an ova and parasite test?

Persistent diarrhea lasting more than a week, unexplained abdominal cramps, weight loss, foul-smelling stool, or a history of travel to areas with poor sanitation are common indications for testing.

How long does it take to get results, and what happens if parasites are found?

Results typically arrive in 1–2 weeks. If parasites are detected, your provider will prescribe appropriate antiparasitic medication, advise on hygiene practices, and may order a follow‑up stool test to confirm clearance.===

Can taking antibiotics before the test affect the results?

Yes, antibiotics can reduce or eliminate parasites, leading to a false negative. If possible, avoid antibiotics for at least 48–72 hours before sample collection, unless they are medically necessary. Discuss timing with your clinician.

Ova and Parasite Test

An ova and parasite test is a laboratory examination of a stool sample used to detect intestinal parasites and their eggs to help diagnose digestive infections.

What is an 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, which are the long, tube-shaped organs in your belly that help digest food. A parasitic infection can cause diarrhea, gas, stomach cramps, and other abdominal 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.

Common Types of Intestinal Parasites

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 U.S., amebiasis happens mostly in people who have been in countries where it is common, including 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, as certain types of intestinal parasites are not easily killed by chlorine.

Other intestinal parasites not common in the U.S. include many types of worms, such as pinworms. These also spread through contaminated soil, water, food, and drink. Some, such as hookworms, can infect you by getting into your skin, especially if you walk barefoot on contaminated ground.

Why do I need an ova and parasite test?

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. These include:

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

Your provider will be more likely to order a test 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. Infants, older adults, and people with conditions like HIV or cancer are at higher risk.
You could have been exposed to parasites, such as by drinking or swallowing water from a stream or lake, traveling to another country where parasites are common, or being around another person with an infection.

What happens during an ova and parasite test?

You will need to provide a stool sample for your test. Your provider will likely give you a container or kit with specific instructions. In general, you will need to:

Label the container with your name, the collection date, and time.
Collect a stool sample using a clean, dry container or special paper/plastic wrap placed over the toilet.
Ensure the stool does not mix with urine, toilet paper, or toilet water.
Close the container tightly and wash your hands well with soap and water.
Return the container according to the instructions.

To get accurate results, you may need to collect several stool samples over a few days, as parasites may not show up in every sample.

What do the results mean?

A negative or normal test result means no parasites or eggs were found. This may mean you do not have parasites, or there were not enough in the sample to be detected.
A positive or abnormal test result means that parasites or eggs were found. Your provider will determine treatment based on the specific type of parasite and your overall health.

Prevention

You can protect yourself from intestinal parasites by:

Washing your hands with warm water and soap after using the bathroom, changing diapers, handling animals, gardening, or preparing food.
Avoiding untreated water from lakes, streams, or rivers.
Boiling water for one to three minutes if you are unsure if it is safe.
Avoiding tap water, ice, and uncooked foods washed with tap water when traveling to areas where water may not be safe.