Dientamoeba fragilis: a bowel pathogen?

Although many patients infected with Dientamoeba fragilis suffer gastrointestinal symptoms, controversy still surrounds the pathogenic role of this intestinal protozoan. We describe three patients infected with D fragilis who had gastrointestinal symptoms. In the first patient symptoms resolved with therapy before the protozoan was eradicated from the stool, however in the second, symptoms persisted unabated despite clearing of the organism. In the third patient, symptoms resolution was associated with effective treatment. We discuss the life cycle, diagnosis and treatment of this organism and its role as a pathogen.