eMedicine Specialties > Pediatrics: General Medicine > Parasitology

Dientamoeba Fragilis Infection

Author: David R Mack, MD, Professor, Department of Pediatrics, University of Ottawa, Canada
Contributor Information and Disclosures

Updated: Jul 24, 2008

Introduction

Background

Dientamoeba fragilis is a nonflagellate trichomonad parasite and is one of the smaller parasites that can live in the human large intestine. Unlike most other intestinal protozoa, its life cycle has no cyst stage; thus, infection between humans occurs during the trophozoite stage. Organisms move most actively in fresh feces but quickly round up when left standing, are sensitive to an aerobic environment, and die and dissociate when placed in saline, tap water, or distilled water. The mode of transmission is believed to be through direct fecal-oral spread and, possibly, through coinfection of eggs of Enterobius vermicularis (ie, pinworm).

Pathophysiology

Organisms infect mucosal crypts of the large intestine that are located close to the mucosal epithelium, from the cecum to the rectum; however, the cecum and proximal colon are usually affected. This parasite is not known to be invasive and does not cause cellular damage. It may invoke an eosinophilic inflammatory response in the colonic mucosa; thus, symptoms are related to the superficial colonic mucosal irritation. Similar to some other parasites (eg, Cyclospora cayetanensis, Giardia lamblia, Cryptosporidium parvum), the parasite D fragilis has been demonstrated to cause disease in humans regardless of their immune status.

Frequency

International

Estimated prevalence in the general population in the United States and in other developed countries is most commonly 2-4%. However, much higher prevalence rates (19-69%) have been reported in specific populations, such as individuals living in crowded conditions (eg, institutions, communal living), individuals living in conditions with poor hygiene, and those traveling to developing countries.

Mortality/Morbidity

Colonization may occur without development of disease. In adults, asymptomatic colonization is present in 75-85% of individuals affected by the parasite. In children, the opposite is true; disease develops in as many as 90% of those colonized.

No specific mortality is associated with this enteropathogen. Morbidity related to acute infection occurs in the first 1-2 weeks of the disease, with symptomatology predominated by diarrhea. Chronic infection occurs after 1-2 months of illness and is manifested by abdominal pain.

Age

Infection may occur at any age. The most common age at which infection has been reported in children is 5-10 years. Interestingly, E vermicularis (pinworm) infection can also occur in the same age group.

Clinical

History

  • Abdominal pain and diarrhea are the most common symptoms.
    • The most common complaints, abdominal pain and diarrhea, commonly occur together following infection with D fragilis.
    • In acute infection, duration of symptoms is 1-2 weeks.
      • Diarrhea predominates in acute infection.1
      • Diarrheal history may vary, with either consistently frequent stools (1-4 stools per day) or episodic occurrence of diarrhea.
      • Stools are greenish brown, and their consistency varies from watery to sticky.
      • Occasionally, mucus is noted in the stools, but hematochezia is unusual.
  • In chronic infection, duration of symptoms is greater than 1-2 months.
    • Abdominal pain is the more common complaint.
    • In children, pain varies with regards to location, duration, and character.
  • Other GI complaints include the following:2
    • Anorexia
    • Weight loss
    • Nausea
    • Vomiting
    • Bloating
    • Flatulence
    • Alternating constipation and diarrhea
  • Nonintestinal complaints include the following:

Physical

  • No specific findings are present on physical examination.
  • General abdominal tenderness may be noted in some children.

Causes

  • The mode of transmission is believed to be through direct fecal-oral spread and, possibly, through the eggs of E vermicularis (pinworm).

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, Professor, Department of Pediatrics, University of Ottawa, Canada
David R Mack, MD 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.com, Inc
Disclosure: Pfizer Inc Stock Investment from broker recommendation; Avanir Pharma Stock Investment from broker recommendation

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 Consulting; MedImmune Honoraria Speaking and teaching; Merck Honoraria Speaking and teaching; Novartis Honoraria Speaking and teaching; sanofi pasteur Grant/research funds Unrestricted research grant; sanofi pasteur  Consulting; sanofi pasteur Honoraria Speaking and teaching; Tap 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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