eMedicine Specialties > Pediatrics: General Medicine > Parasitology

Dientamoeba Fragilis Infection: Differential Diagnoses & Workup

Author: David R Mack, MD, FRCPC, Professor, Departments of Pediatrics and Biochemistry, Microbiology, and Immunology, University of Ottawa Faculty of Medicine; Head, Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, Children's Hospital of Eastern Ontario, Canada
Contributor Information and Disclosures

Updated: Jul 24, 2008

Differential Diagnoses

Amebiasis
Irritable Bowel Syndrome
Campylobacter Infections
Isosporiasis
Colitis
Lactose Intolerance
Cyclosporiasis
Malabsorption Syndromes
Enteroviral Infections
Protein Intolerance
Escherichia Coli Infections
Salmonella Infection
Gastroenteritis
Somatoform Disorder: Pain
Giardiasis
Soy Protein Intolerance
Intestinal Protozoal Diseases

Other Problems to Be Considered

Allergic gastroenteritis
Eosinophilic gastroenteritis
Celiac disease

Workup

Laboratory Studies

  • Blood tests
    • Blood test results are usually normal.
    • However, a CBC count with differential may reveal eosinophilia in as many as 50% of children infected with the parasite.
  • Stool evaluation
    • The usual method for confirming the diagnosis is examination of a permanently stained smear of fresh feces, preserved immediately, for the morphologic characteristics of D fragilis trophozoites.
    • Newer, but experimental, techniques include immunofluorescence and real-time polymerase chain reaction (PCR) techniques.3 Culture is not routinely available.
    • Preferred stool preparation involves a fresh sample that is immediately preserved with polyvinyl alcohol fixative, sodium acetate-acetic acid-formalin fixative, or Schaudinn fixative.
    • Immediate preservation is necessary because, in unpreserved feces, the morphologic characteristics of the trophozoites do not persist, and they round up and become granular within 15 minutes at room temperature.
    • A single sample is diagnostic only 50-60% of the time.
    • Three separate samples increase the yield to 70-85%, and 6 separate samples increase the yield to 90-95%.
    • Ensure that stool samples are collected on alternate days because D fragilis can be excreted in a cyclic pattern similar to G lamblia.
    • The final portion of the stool evacuation may contain the most concentrated numbers of trophozoites.
    • Collect stool specimens before radiologic procedures that use barium because barium interferes with trophozoite detection and may do so for several weeks.
    • Other medications that can interfere with parasite detection include antibiotics, antiprotozoan medication, antimalarials, mineral oil, bismuth-containing preparations, and nonabsorbable diarrheal medications.
    • Process stool specimens in the laboratory with the formalin-ether sedimentation concentration technique and stain with either iron hematoxylin, trichrome, or celestin B.
  • Diagnostic characteristics
    • Diagnostic characteristics are a pleomorphic trophozoite ranging in diameter from 5-15 mm (range, 4-30 mm) that contains 1-4 nuclei.
    • The most common form is binucleated. However, approximately 20-30% are uninucleated. Multinucleated forms also can be present.
    • The nuclei are distinctive, with several (4-8) chromatin granules clumped in the center of each nucleus.
    • The cytoplasm frequently contains numerous food vacuoles.

Imaging Studies

  • Radiologic test findings are usually normal.

More on Dientamoeba Fragilis Infection

Overview: Dientamoeba Fragilis Infection
Differential Diagnoses & Workup: Dientamoeba Fragilis Infection
Treatment & Medication: Dientamoeba Fragilis Infection
Follow-up: Dientamoeba Fragilis Infection
References
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References

  1. Cuffari C, Oligny L, Seidman EG. Dientamoeba fragilis masquerading as allergic colitis. J Pediatr Gastroenterol Nutr. Jan 1998;26(1):16-20. [Medline].

  2. Johnson EH, Windsor JJ, Clark CG. Emerging from obscurity: biological, clinical, and diagnostic aspects of Dientamoeba fragilis. Clin Microbiol Rev. Jul 2004;17(3):553-70, table of contents. [Medline].

  3. Verweij JJ, Mulder B, Poell B, van Middelkoop D, Brienen EA, van Lieshout L. Real-time PCR for the detection of Dientamoeba fragilis in fecal samples. Mol Cell Probes. Oct-Dec 2007;21(5-6):400-4. [Medline].

  4. Butler WP. Dientamoeba fragilis. An unusual intestinal pathogen. Dig Dis Sci. Sep 1996;41(9):1811-3. [Medline].

  5. Frenkel LM. Dientamoeba fragilis infection. In: Textbook of Pediatric Infectious Diseases. Vol 2. 4th ed. Elsevier Health Sciences; 1998:2403-6.

  6. Grendon JH, DiGiacomo RF, Frost FJ. Descriptive features of Dientamoeba fragilis infections. J Trop Med Hyg. Oct 1995;98(5):309-15. [Medline].

  7. Keystone JS, Yang J, Grisdale D, et al. Intestinal parasites in metropolitan Toronto day-care centres. Can Med Assoc J. Oct 1 1984;131(7):733-5. [Medline].

  8. Kurt O, Girginkardesler N, Balcioglu IC, Ozbilgin A, Ok UZ. A comparison of metronidazole and single-dose ornidazole for the treatment of dientamoebiasis. Clin Microbiol Infect. Jun 2008;14(6):601-4. [Medline].

  9. Medical Letter on Drugs and Therapeutics. Drugs for parasitic infections. Med Lett Drugs Ther. Mar 6 1992;34(865):17-26. [Medline].

  10. Norberg A, Nord CE, Evengard B. Dientamoeba fragilis--a protozoal infection which may cause severe bowel distress. Clin Microbiol Infect. Jan 2003;9(1):65-8. [Medline].

  11. Preiss U, Ockert G, Broemme S, Otto A. On the clinical importance of Dientamoeba fragilis infections in childhood. J Hyg Epidemiol Microbiol Immunol. 1991;35(1):27-34. [Medline].

  12. Shein R, Gelb A. Colitis due to Dientamoeba fragilis. Am J Gastroenterol. Oct 1983;78(10):634-6. [Medline].

  13. Spencer MJ, Garcia LS, Chapin MR. Dientamoeba fragilis. An intestinal pathogen in children?. Am J Dis Child. Apr 1979;133(4):390-3. [Medline].

  14. Spencer MJ, Millet VE, Garcia LS, et al. Parasitic infections in a pediatric population. Pediatr Infect Dis. Mar-Apr 1983;2(2):110-3. [Medline].

  15. Stark DJ, Beebe N, Marriott D, et al. Dientamoebiasis: clinical importance and recent advances. Trends Parasitol. Feb 2006;22(2):92-6. [Medline].

  16. Turner JA. Giardiasis and infections with Dientamoeba fragilis. Pediatr Clin North Am. Aug 1985;32(4):865-80. [Medline].

  17. Vandenberg O, Peek R, Souayah H, Dediste A, Buset M, Scheen R. Clinical and microbiological features of dientamoebiasis in patients suspected of suffering from a parasitic gastrointestinal illness: a comparison of Dientamoeba fragilis and Giardia lamblia infections. Int J Infect Dis. May 2006;10(3):255-61. [Medline].

  18. Vandenberg O, Souayah H, Mouchet F, Dediste A, van Gool T. Treatment of Dientamoeba fragilis infection with paromomycin. Pediatr Infect Dis J. Jan 2007;26(1):88-90. [Medline].

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Further Reading

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Keywords

Dientamoeba fragilis, D fragilis, Enterobius vermicularis, pinworm, trichomonad parasite, intestinal protozoa, large intestine parasite, Cyclospora cayetanensis, Giardia lamblia, Cryptosporidium parvum, diarrhea

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Contributor Information and Disclosures

Author

David R Mack, MD, FRCPC, Professor, Departments of Pediatrics and Biochemistry, Microbiology, and Immunology, University of Ottawa Faculty of Medicine; Head, Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, Children's Hospital of Eastern Ontario, Canada
David R Mack, MD, FRCPC is a member of the following medical societies: American Gastroenterological Association, Canadian Association of Gastroenterology, and North American Society for Pediatric Gastroenterology and Nutrition
Disclosure: Nothing to disclose.

Medical Editor

Michael D Nissen, MBBS, BMedSc, FRACP, FRCPA, Associate Professor in Biomolecular, Biomedical Science & Health, Griffith University; Director of Infectious Diseases and Unit Head of Queensland Paediatric Infectious Laboratory, Sir Albert Sakzewski Viral Research Centre, Royal Children's Hospital
Michael D Nissen, MBBS, BMedSc, FRACP, FRCPA is a member of the following medical societies: American Academy of Pediatrics, American Society for Microbiology, Pediatric Infectious Diseases Society, Royal Australasian College of Physicians, and Royal College of Pathologists of Australasia
Disclosure: Nothing to disclose.

Pharmacy Editor

Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine
Disclosure: Pfizer Inc Stock Investment from financial planner; Avanir Pharma Stock Investment from financial planner ; WebMD Salary and stock Employment and investment from financial planner

Managing Editor

Martin Weisse, MD, Program Director, Associate Professor, Department of Pediatrics, West Virginia University
Martin Weisse, MD is a member of the following medical societies: Ambulatory Pediatric Association, American Academy of Pediatrics, and Pediatric Infectious Diseases Society
Disclosure: Nothing to disclose.

CME Editor

Robert W Tolan Jr, MD, Chief, Division of Allergy, Immunology and Infectious Diseases, The Children's Hospital at Saint Peter's University Hospital; Clinical Associate Professor of Pediatrics, Drexel University College of Medicine
Robert W Tolan Jr, MD is a member of the following medical societies: American Academy of Pediatrics, American Medical Association, American Society for Microbiology, American Society of Tropical Medicine and Hygiene, Infectious Diseases Society of America, Pediatric Infectious Diseases Society, Phi Beta Kappa, and Physicians for Social Responsibility
Disclosure: GlaxoSmithKline Honoraria Speaking and teaching; MedImmune Honoraria Speaking and teaching; Merck Honoraria Speaking and teaching; sanofi pasteur Honoraria Speaking and teaching; Baxter Healthcare Honoraria Speaking and teaching

Chief Editor

Russell W Steele, MD, Head, Division of Pediatric Infectious Diseases, Ochsner Children's Health Center; Clinical Professor, Department of Pediatrics, Tulane University School of Medicine
Russell W Steele, MD is a member of the following medical societies: American Academy of Pediatrics, American Association of Immunologists, American Pediatric Society, American Society for Microbiology, Infectious Diseases Society of America, Louisiana State Medical Society, Pediatric Infectious Diseases Society, Society for Pediatric Research, and Southern Medical Association
Disclosure: None None None

 
 
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