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Dientamoeba Fragilis Infection Workup

  • Author: David R Mack, MD, FRCPC; Chief Editor: Russell W Steele, MD  more...
 
Updated: Aug 18, 2015
 

Laboratory Studies

Blood tests

Blood test results are usually normal in patients with Dientamoeba fragilis infection. 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.[8] 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.

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Imaging Studies

Radiologic test findings are usually normal.

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Contributor Information and Disclosures
Author

David R Mack, MD, FRCPC Professor, Department of Pediatrics, 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: Canadian Paediatric Society, Canadian Association of Gastroenterology, American Gastroenterological Association, North American Society for Pediatric Gastroenterology, Hepatology and Nutrition

Disclosure: Nothing to disclose.

Specialty Editor Board

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

Martin Weisse, MD Program Director, Associate Professor, Department of Pediatrics, West Virginia University

Martin Weisse, MD is a member of the following medical societies: Academic Pediatric Association, American Academy of Pediatrics, Pediatric Infectious Diseases Society

Disclosure: Nothing to disclose.

Chief Editor

Russell W Steele, MD Clinical Professor, Tulane University School of Medicine; Staff Physician, Ochsner Clinic Foundation

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, Southern Medical Association

Disclosure: Nothing to disclose.

Additional Contributors

Michael D Nissen, MBBS 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 is a member of the following medical societies: American Academy of Pediatrics, Royal College of Pathologists of Australasia, Royal Australasian College of Physicians, American Society for Microbiology, Pediatric Infectious Diseases Society

Disclosure: Nothing to disclose.

References
  1. Stark D, Roberts T, Marriott D, Harkness J, Ellis JT. Detection and transmission of Dientamoeba fragilis from environmental and household samples. Am J Trop Med Hyg. 2012 Feb. 86(2):233-6. [Medline]. [Full Text].

  2. Clark CG, Röser D, Stensvold CR. Transmission of Dientamoeba fragilis: pinworm or cysts?. Trends Parasitol. 2014 Mar. 30(3):136-40. [Medline].

  3. Cacciò SM, Sannella AR, Manuali E, Tosini F, Sensi M, Crotti D, et al. Pigs as natural hosts of Dientamoeba fragilis genotypes found in humans. Emerg Infect Dis. 2012 May. 18(5):838-41. [Medline]. [Full Text].

  4. New Research Questions Pathogenicity of Parasite D fragilis. Medscape. Available at http://www.medscape.com/viewarticle/825137. Accessed: 9/9/14.

  5. Stark D, Barratt J, Roberts T, Marriott D, Harkness J, Ellis J. A review of the clinical presentation of dientamoebiasis. Am J Trop Med Hyg. 2010 Apr. 82(4):614-9. [Medline]. [Full Text].

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

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

  8. 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. 2007 Oct-Dec. 21(5-6):400-4. [Medline].

  9. Röser D, Simonsen J, Stensvold CR, Olsen KE, Bytzer P, Nielsen HV, et al. Metronidazole therapy for treating dientamoebiasis in children is not associated with better clinical outcomes: a randomized, double-blinded and placebo-controlled clinical trial. Clin Infect Dis. 2014 Jun. 58(12):1692-9. [Medline].

  10. Röser D, Simonsen J, Nielsen HV, Stensvold CR, Mølbak K. History of antimicrobial use and the risk of Dientamoeba fragilis infection. Eur J Clin Microbiol Infect Dis. 2015 Jun. 34 (6):1145-51. [Medline].

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

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

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

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

  15. 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. 2008 Jun. 14(6):601-4. [Medline].

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

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

  18. 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].

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

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

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

  22. 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. 2006 May. 10(3):255-61. [Medline].

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

 
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This is an illustration of the assumed life cycle of Dientamoeba fragilis, the cause of a protozoan parasitic infection.
 
 
 
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