Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at August 18, 2016

Parasites most commonly affect the gastrointestinal tract, and dientamoebiasis is no exception. This medical condition is caused by a parasitic infection, and it can cause many severe gastrointestinal issues if left untreated.


Definition & Facts

Dientamoebiasis is a parasitic infection caused by the dientamoeba fragilis parasite. This parasite is a type of protozoan that lives in a variety of climates across the world, and every country has reports of dientamoeba fragilis infections. Only 9.4 percent of people in the United States get dientamoebiasis, but infection rates spike up to 42 percent in developing nations.

This parasite has been found by some reports to be the most common cause of a protozoan parasitic infection. There are both pathogenic and nonpathogenic varieties of the dientamoeba fragilis, so symptoms can vary wildly depending on what particular strain of the parasite is infecting a patient. The parasite that causes dientamoebiasis mostly resides in the lower areas of the human gastrointestinal system.

Symptoms & Complaints

Symptoms tend to be more severe in children, the elderly, and other immunocompromised patients.

If a patient is infected with a nonpathogenic version of this parasite, they may exhibit little to no symptoms. They may just experience a minor amount of fatigue and random, vague feelings of abdominal discomfort.

However, many people get a more harmful strain of the dientamoeba fragilis parasite which causes severe gastrointestinal distress. It often results in severe stomach pain, nausea, and chronic diarrhea that can last for several weeks. Occasionally, patients with dientamoebiasis may start vomiting, develop a fever, and suffer from an itchy skin rash.

The gastrointestinal issues tend to cause a loss of appetite and an increase in fatigue. Many patients have difficulty eating or absorbing nutrients from foods, so they lose weight and experience symptoms of malnutrition. Children who have dientamoebiasis are often first diagnosed with a failure to thrive if the more severe symptoms of dientamoebiasis are not immediately evident.


The dientamoeba fragilis parasite is a type of organism that causes dientamoebiasis in humans. Though this parasite cannot survive outside of a host organism for more than a few hours, it still spreads extremely quickly. Most people get dientamoebiasis after drinking contaminated water or eating contaminated food that contains feces from another person who has dientamoebiasis.

In addition to the fecal-oral route, another mode of transmission that is theorized though unconfirmed is that the parasite is transmitted via pinworms and other types of parasites. These parasites may act as a host for the tiny dientamoeba fragilis organisms, and these parasites can survive without a human host for quite a while. It is very common for patients who have pinworms and other common parasites to also develop dientamoebiasis. Dientamoeba fragilis may be transmitted through animals (zoonosis) such as apes, sheep, parrots, and pigs, but it is not commonly spread from normal household pets to humans.

Not all types of dientamoebiasis cause issues, but a strain of dientamoebiasis is more likely to cause health problems if the person who contracts it has a weakened immune system.

Diagnosis & Tests

It is somewhat difficult for a doctor to identify dientamoebiasis based on just a physical examination and medical history because the gastrointestinal symptoms are so vague. Typically, dientamoebiasis is suspected if a patient is exhibiting signs of a parasitic infection without any obvious parasites like tapeworms present.

Basic stool examinations do not always reveal the presence of the dientamoeba fragilis parasite because they die quickly and are no longer easily identifiable. Therefore, it is normally necessary to collect stool samples and send them to a professional parasitologist. Tests normally need to be done on both formed stool samples and soft stool samples, since different forms of the parasite may be present in both. The specimens must be immediately preserved before being sent to a parasitologist for examination because dientamoeba fragilis traces become unidentifiable so easily.

Sometimes parasite specimens are evident with a microscope, but using indirect fluorescent antibody methods can make it a little quicker for the analyst to find the parasites. It is also possible to culture a sample of the parasite from an unpreserved stool sample, but this is somewhat time consuming. Once presence of dientamoeba fragilis parasites is confirmed, a doctor will normally diagnose a patient with dientamoebiasis.

Treatment & Therapy

Since the dientamoeba fragilis parasite is a type of protozoa, the most effective treatment is an antiprotozoal medication. Commonly prescribed antiprotozoal medicines are metronidazole, tetracycline, or iodoquinol. Other antibiotic and antiparasitic medications such as flagyl are also prescribed sometimes, but the most effective drugs for dientamoebiasis can be harmful for children under the age of eight, lactating women, or pregnant women.

Since children are very likely to get dientamoebiasis, other child friendly medications have been developed. Diiodohydroxyquinoline is a particularly effective and safe medication for children who have dientamoebiasis. To alleviate symptoms until the parasites are removed, a doctor may recommend anti-nausea medications, anti-diarrheal medicine, and painkillers.

It is important to get a lot of bed rest and remain hydrated while recovering from dientamoebiasis. Because dientamoebiasis is so commonly spread by other parasites, a doctor may recommend that a patient also take treatments for pinworms or other parasites to avoid contracting it again.

Prevention & Prophylaxis

Most preventative methods to avoid getting dientamoebiasis will rely on avoiding contact with infected patients whenever possible. If a person is around someone else who has dientamoebiasis, regularly washing their hands with antibacterial soap and avoiding physical contact is recommended if possible. In general, regularly washing hands can help to prevent dientamoebiasis, since it often spreads if a person touches an infected surface.

Since it is more common in developing countries, people who are traveling are advised to avoid drinking or eating items unless they are properly cooked and sanitized.