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The Life Cycle of Dientamoeba Fragilis

Dientamoeba fragilis, a parasite that grows in the large intestine, or human bowel, causes gastrointestinal infections. This protozoan is a flagellate and not an amoeba, and produces trophozoites, which are a stage in the life cycle of the protozoan where it is capable of locomotion and feeds on the host, that multiply in number causing various health problems. A protozoan is a single-celled organism and in this case, the Dientamoeba has a whip-like extension from its unicellular body which allows it to propel and move. Though Dientamoeba fragilis was discovered by scientists nearly 100 years ago, its life cycle is not very clearly established. In fact, experts are still unclear about how it is transmitted.

Life Cycle
- It is theorized that transmission of Dientamoeba fragilis occurs mainly through the fecal-oral route by consumption of contaminated food and/or water. The trophozoites are found in excreta of infected people. The parasite does not appear to have a cyst stage. Once transmission is successful, the trophozoites multiply through asexual reproduction and form huge colonies in the large intestine. At this stage, the lining of the large intestine erodes due to the presence of the parasites, but they do not enter the tissue. The trophozoites are again sent out of the body through the feces, and have the ability to infect another person when ingested. The period of incubation of the parasite is still not clearly known.
Other Transmission Theories
- Because it is not clear how the protozoan is transmitted, there are various theories on it. One theory suggests that Dientamoeba fragilis may be transmitted through animals. However, molecular research proves that the existence of this parasite in animals is quite sporadic. Another theory claims that the transmission occurs through eggs of helminths, which are parasitic worms living in the body, such as ascaris and Enterobius spp.
Symptoms
- The Dientamoeba fragilis parasite infection is quite common across many parts of the world, including the United States. The most common symptoms include pain in the abdomen and diarrhea. The infection may also be accompanied by nausea, debility, loss of weight and appetite, and fatigue. However, the infection does not spread to other body parts from the large intestine. While some people show symptoms of infection, in others there are no obvious symptoms of the protozoan.
Diagnosis
- Stool samples are tested more than once, as every stool sample may not show the parasitical infection. Many times, people infected with Dientamoeba fragilis also suffer from pinworms infestation. In case you observe the aforementioned symptoms, consult your doctor for further assistance. The infection is treated using appropriate medications suggested by the professional. The CDC recommends iodoquinol or metronidazole for treating Dientamoeba fragilis infection.
Prevention
- A simple hygiene routine of washing hands with warm water and soap after using the restroom, changing diapers, before touching food and prior to food preparation is one of the easiest ways of preventing Dientamoeba fragilis infection.

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