Clinical Features:
Symptoms that have been associated with infection include diarrhea, abdominal pain, anorexia, nausea, vomiting, fatigue, and weight loss.

Laboratory Diagnosis:
Infection is diagnosed through detection of trophozoites in permanently stained fecal smears (e.g., trichrome).  This parasite is not detectable by stool concentration methods.  Dientamoeba fragilis trophozoites can be easily overlooked because they are pale-staining and their nuclei may resemble those of Endolimax nana or Entamoeba hartmanni.

Diagnostic findings

• Microscopy
• Morphologic comparison with other intestinal parasites

Treatment:
Safe and effective drugs are available.  The drug of choice is iodoquinol.  Paromomycin*, tetracycline*, (contraindicated in children under age 8, pregnant and lactating women) or metronidazole can also be used.  For additional information, see the recommendations in The Medical Letter (Drugs for Parasitic Infections).

* This drug is approved by the FDA, but considered investigational for this purpose.