Dientamoeba

• Dientamoeba fragilis


  Not an amoeba but a flagellate
• Dientamoeba fragilis


  • Only trophozoites
  • No cysts

  
• Infection may be


  • Symptomatic
  • Asymptomatic
• Trophozoite


  • 7 - 12 um
  • 1 - 2 rosette shaped nuclei
  • Nuclear membrane NO chromatin
  • Karyosome 4 - 6 discreet granules
  • Cytoplasm may contain vacuoles with ingested debris
  • Resembles Trichomonas
• Life Cycle of Dientamoeba fragilis

  1. Infective and Diagnostic stage: trophozoite

  2. Habitat: Mucosal crypt, appendix, cecum, upper colon

  3. Transmission: Fecal to oral route

  4. Via helminth egg Enterobius vermicularis - common associated infection

  5. Can also be carried by the Ascaris ova

  6. Animal reservoir: Macaque, gorillas, swine

  
• Pathology


  • Does not invade tissues
  • Irritation of mucosa
  • Secretion of excess mucus and hypermobility of the bowel
• Symptomatic


  • Loss of appetite
  • Colicky abdominal pain
  • Intermitted diarrhea
  • Excess mucus
  • Abdominal tenderness
  • Bloating sensation
  • Flatulence
  • Anal pruritus
  • Peripheral eosinophilia (50%)
  • Inflammatory Bowel Syndrome
• Diagnosis


  1. Demonstration of Binucleate trophozoite

  2. Multiple fixed and stained

  3. Prompt fixation of fresh sample

  4. Polyvinyl alcohol fixative

  5. Schaudinn's fixative

  6. Fresh stool samples
• Treatment


  • Iodoquinol 650 mg TID for 20 days
  • Tetracycline
  • Metronidazole