Dientamoeba Fragilis Infection

Medically Reviewed by Carol DerSarkissian, MD on May 06, 2023
Written by WebMD Editorial Contributors
2 min read

Dientamoeba fragilis is a parasite that lives in the large intestine of humans. Infection is common worldwide, including in the U.S.

Many people infected with dientamoeba fragilis do not have any symptoms. The most common symptoms are diarrhea, stomach pain, and stomach cramping. Loss of appetite and weight, nausea, and fatigue also are common. The infection does not spread from the intestines to other parts of the body.

To diagnose dientamoeba fragilis, your doctor will ask you to provide stool samples for testing. Because the parasite is not always found in every stool sample, you might be asked to submit stool samples from more than one day. You might also be tested for pinworm eggs, which are commonly (but not always) found in persons infected with D. fragilis.

Safe and effective medications are available for D. fragilis and pinworm infections.

No one knows how D. fragilis is spread. The parasite is fragile and probably cannot live very long in the environment. Infection might be spread by:

  • Accidentally swallowing pinworm eggs (which might protect this fragile parasite) or the eggs of other parasites.
  • Swallowing something, such as water or food, or touching (and bringing your fingers to your mouth) something contaminated with stool from someone infected with D. fragilis.

Anyone can become infected with this parasite. However, the risk for infection might be higher for people who live in or travel to settings with poor sanitary conditions or who have weak immune systems.

To prevent infection:

  • Wash your hands with soap and warm water, especially after using the toilet, changing baby diapers, and before preparing foods.
  • Teach children the importance of washing hands to prevent infection.