Molecular testing for Dientamoeba fragilis is used for the diagnosis and laboratory documentation of dientamoebiasis.
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Dientamoeba fragilis is one of the smaller protozoa parasitizing in the human digestive tract. Dientamoeba fragilis is a flagellated protozoan that, unlike other intestinal protozoan parasites, does not have a cyst stage. It occurs only in the form of a trophozoite. The target location is the large intestine. Dientamoeba fragilis does not move outside the digestive tract to other organs. The mode of transmission of infection is not well understood, but the zoonotic nature of the disease is likely. There are two main theories of how D. fragilis spreads. (1) D. fragilis may be spread through contamination of hands, objects, or food with infected faeces. The parasite is then taken in by the mouth. (2) Alternatively, D. fragilis may be spread by other parasites like Enterobius vermicularis (pinworm). Dientamoeba fragilis is believed to be transmitted between human hosts inside helminth eggs or larvae, particularly those of Enterobius vermicularis. The evidence for this is the frequent association between the two organisms and the presence of bodies inside the helminth eggs, which resemble D. fragilis. The prevalence of infections with both organisms (Dientamoeba fragilis and Enterobius vermicularis) is ninefold greater than would be expected based on just a random association.
Dientamoebiasis (the disease caused by Dientamoeba fragilis) occurs all over the world, much more frequently in regions of high population density. If clinical symptoms occur during the course of the infection, they are usually mild and include diarrhea, abdominal pain, and lack of appetite, which vary in intensity. Asymptomatic colonization occurs in 75-85% of infected adults, and in children, symptoms appear in 90% of cases. Symptoms of an acute infection persist for 1-2 weeks. Stools are brown-green, sometimes with mucus. The symptom of chronic infection is abdominal pain lasting several months. Currently, however, the ability of Dientamoeba fragilis to cause disease symptoms is questioned.
The laboratory method of choice for the detection of the protozoan is molecular testing by PCR.
