The pathogenicity of D.fragilis continues to be questioned; however, the circumstantial evidence incriminating this organism as a pathogen is overwhelming. D.fragilis: the unflagellated human flagellate. JJ Windsor & EH Johnson, Br.J.Biomed Sci 1999.

D.fragilis is considered by many to be nonpathogenic and is often ignored. Such appears unjustified in view of cases reported in the literature and cases reviewed. Specific therapy seems warranted. The Neglected Ameba: Dientamoeba fragilis. Kean et al. Am. J. Dig. Dis. Vol 11. No. 9. 1966)

In 1937, Hakansson collected a group of 12 patients with D.fragilis in the stool. For each an adequate history was taken; 6 indicated recurrent gastroeintestinal distress in the form of mild cramps, borborygmus (rumbling sound caused by gas), mushy stools, or rectal irritation. The Neglected Ameba: Dientamoeba fragilis. Kean et al. Am. J. Dig. Dis. Vol 11. No. 9. 1966)

Burrows recorded a D.fragilis infection in himself (Amer. J. Trop. Med. 1956). He correlated the occurrence nearly every two weeks of soft stools, abdominal fullness, gas, and discomfort with periods when D.fragilis was most abundant in the stools.The Neglected Ameba: Dientamoeba fragilis. Kean et al. Am. J. Dig. Dis. Vol 11. No. 9. 1966)

Observations of symptomatic recovery of patients after treatment of D.fragilis infection would indicate a pathogenic role for this parasite in children. We conclude that symptoms should be treated. Dientamobic infections.
Spencer et al. Am. J. Dis. Child. Vol 133. April 1979

The potential pathogenicity of D.fragilis is supported by the finding that cases with only D.fragilis detected in stool specimens were just as likely to be symptomatic as cases with D.fragilis and other protozoans or helminths. In both groups, dirrhoea or loose stools were the most common symptom.
Descriptive feature of D.fragilis infections. Grendon et al. Journal of Trop. Med. & Hygiene 1995,, 98, 309-315

Failure to diagnose is the major potential legal pitfall. This is particularly true in the rare occurrence that failure to thrive ensues. Dientamoeba fragilis.
D.R. Mack, MD. E-medicine. 2003

Most recent literature accepts that D. fragilis is an important enteric pathogen with an estimated incidence of symptomatic infection of between 4 and 91%. Symptoms include abdominal pain, bloating, and diarrhea. Peek et al, 2004,
American Society for Microbiology

A report on intestinal disorders accompanied by large numbers of Dientamoeba fragilis. J Trop Med Hyg. 1955 Feb;58(2):38-41.

Pathology of Dientamoeba fragilis infections of the appendix. Burrows RB, Swerdlow MA, Frost JK, Leeper CK.
Am J Trop Med Hyg. 1954 Nov;3(6):1033-9.


"Dientamoeba fragilis - a protozoal infection
which may cause severe bowel distress.

Clin Microbiol Infect. 2003 Jan;9(1):65-8 Norberg A, Nord CE, Evengard B.

"I went to the first specialist in 1992 and he didn't bother to test for (Dientamoeba fragilis), told me that the good news was that I didn't have cancer or Crohn's disease and that I would just have to learn to live with the symptoms of IBS which were (in his opinion) largely stress related!"

Dientamoeba fragilis was found after 8 years of chronic digestive and other symptoms, misdiagnosed as IBS. USA. (2005)

Symptoms D.fragilis

The symptoms of D.fragilis are similar to Blasto. The most common symptoms cited in the medical literature are:

  • Abdo. pain
  • Constipation
  • Diarrhoea
  • Anorexia
  • Weight loss
  • Fever
  • Irritability
  • Vomiting
  • Fatigue

Other symptoms frequently reported to this site are:

  • Cravings for sweets foods and carbohydrates
  • Thick white/green tongue coating
  • Undigested foods particles in stool
  • Shortness of breath
  • Racing heart
  • Feeing faint
  • Inability to concentrate (foggy thinking)
  • Depression

Less comon:

  • Feelings of doom.
  • Panic attacks
  • Burning sensation in colon

Read suprising facts about our immune response to infection and the symptoms of a parasitic infection here.

From the scientific literature

Clinical reports have suggested that Dientamoeba fragilis may be a cause of acute and chronic colitis in children and adults. The mechanism by which this parasite process produces colitis has not been determined. The clinical findings of this report suggest that D.fragilis causes colitis through an invasive ulcerating process. Shein R. Gelb.A. Colitis due to dientamoeba fragilis. Am. J Gastroenterol. 1983; 78(10): 634-6

D Fragilis is thought to inhabit the mucosal crypts of the large intestine (1).
Although it is considered to be non-invasive one case of colitis attributed to this organism has been reported (2).

( 1) Markell E.K, Voge M, Medical parasitology, 5th ed. Philadelphia: Saunders 1981; 61-63
(2) Shein R, Gelb A. Colitis due to dientamoeba fragilis. Am.J.Gastroenterology 1983; 78: 634-6 & Dientamoeba fragiis: a bowel pathogen? Robert Oxner et al. New Zealand Medical Journal. 11 Feb. 87

Dientamoeba fragilis is a rare cause of chronic infectious diarrhoea and colitis in children. Eosinophilic colitis documented by colonoscopy, was due to D. fragilis. CONCLUSIONS: D. fragilis should be included in the differential diagnosis of chronic diarrhoea and eosinophilic colitis. Dientamoeba fragilis masquerading as allergic colitis. Cuffari C, Oligny L, Seidman EG Department of Pediatrics, Hopital Sainte-Justine, Universite de Montreal, Canada J Pediatr Gastroenterol Nutr 1998 Jan;26(1):16-20 . Eur J Pediatr 1997 Jul;156(7):583

Of special interest are the reports by a few parasitologists and physicians who themselves, or whose relatives, were infected by this parasite. Mushy stools, abdo. pains, fatigue, loss of appetite and weight loss were among the symptoms experienced. Irritation of the intestinal wall, fibrosis of the appendix, edema of the mucosa, phagocytosis of red blood cells, low grade eosinophilia, and occurence of biliary tracts, have also been reported. D Fragilis: A Review with Notes on its Epidemiology, pathogenicity, mode of transmission, and diagnoses. J Yang and TH Scholten, AMJ of Tropical Med. & Hygiene. 1977 Vol 26, No.1

Dientamoeba fragilis does not invade tissues but there is some evidence that its presence in the intestine occasionally produces irritation of the mucosa, with secretion of excess mucosa and hypermotility of the bowel. In a series of cases in adults and children, Knoll and Howard (1945) reported nausea, vomiting, low-grade fever, diarrhoea, and abdo. discomfort with symptomatic cure following appropriate anti-amoebic therapy. The manifestations usually attributed to this infection consist mostly of mucous diarrhoea, with vague to moderate regional abdo. pain and tenderness. The next most common symptom (after diarrhoea, abdominal pain) which was reported in 11% of the patients was pruritis. J.Clinical Parasitology. 9th Ed. Beaver, Jung & Cupp, 1984

A detailed description of abdominal symptoms was recorded in the medical record of 10 patients with chronic complaints. In the majority, abdominal pain occurred 15-60 min after meals, was described as "crampy" or "burning" and was not relieved by antacids. One patient had pain at the onset of each meal and two had constant abdominal pain. Pain was occasionally associated with nausea and/or vomiting ; intermittent diarrhoea was frequent. Pain was localized to the epigastrium in five patients, in the upper quadrant in four, and in the lower quadrant in four. Postprandial diarrhoea associated with abdominal pain occurred in two patients; eight patients had frequent loose or watery bowel movements (3-6/day) . One patient had a 1-yr history of fatigue and diarrhoeal stools consisting of watery or soft bowel movements which occurred 15 to 30 min after each meal. Parasites were frequently not thought to be the etiological agent of gastrointestinal symptoms. Dientamoeba fragilis: A Gastrointestinal Protozoan Infection in Adults. Mary J. Spencer, M.D., Martha R. Chapin, R.N., and Lynne S. Garcia, M.T.(ASCP) Am.J.of Gastro. Vol.77. No.8. 1982

Clinical manifestations of infectious diarrhoea included anorexia, intermittent vomiting, abdominal pain, and diarrhoea, ranging from 1 to 100 weeks in duration . Peripheral eosinophilia was present in seven patients. One patient with well-documented bovine protein allergy had intermittent episodes of diarrhoea and abdominal pain, despite an appropriate elimination diet. Dientamoeba fragilis masquerading as allergic colitis. Cuffari C, Oligny L, Seidman EG Department of Pediatrics, Hopital Sainte-Justine, Universite de Montreal, Canada. J Paediatr Gastroenterol Nutr 1998 Jan;26(1):16-20

Hakansson proposed that GI disturbances with D fragilis is secondary to a superficial irritation of the intestinal mucosa, which is the result of the organism in the faecal mass that changes a formed stool to a sticky, irritating mass, often accompanied by diarrhoea and/or vague abdo. symptoms. Am.J.Trop.Med 16:175-183, 1936

Gastrointestinal symptoms occur in one quarter to one half of infected patients. These include abdo.pain, diarrhoea, flatus, anorexia, nausea and vomiting, weight loss, anal pruritius and fatigue. Symptoms may persist from weeks to years.
D fragilis - a bowel pathogen? Oxner et al. New Zealand Medical Journal 1987

In the past 60 years, there have been scattered reports of D.F. being found in the stool specimens of children with a history of anorexia, fatigue, peripheral eosinophilia, and chronic recurrent intestinal symptoms, including lower abdo. pain, flatulence, diarrhoea and constipation. During the past two years at UCLA, we noted a number of children with both acute and chronic GI symptoms in whom DF was observed in stool samples submitted for ova and parasite examinations. D.fragilis - an intestinal pathogen in children? Mary J. Spencer, M.D., Martha R. Chapin, (Am J Dis Child 133:390-393, 1979)

A 22 yo caucasian female librarian presented with an 18 month history of increasingly frequent attacks of hypogastric pain, borborygmi, offensive flatus and occasional diarrhoea. The pain would start late afternoon and be severe by bedtime. Occasionally it would wake her during the night. Physical examination, sigmoidoscopy, gastroscopy and small bowel biopsy were normal. Blood screen, electrolytes, renal and liver function tests were normal. Stool parasite examinations showed D Fragilis trophozoites....

A 28 yo caucasian male teacher presented with a four week history of cramping and right iliac fossa pains, diarrhoea up to eight times a day and slight weight loss. Physical examination including sigmoidoscopy was normal. Blood screen, electrolytes, renal and liver function tests were normal. Stool parasite examinations revealed DF trophozoites....

A 39 yo caucasian male teacher presented with a two month history of altered bowel habit, left iliac fossa pain, abdominal distension, borborygmi, mild anorexia, nausea and a 2 kg weight loss. About once a week he experienced a feeling of abdominal distension, mild left iliac fossa pain and borborygmi after the evening meal. These symptoms would continue throughout the night until 4 am when he would pass a large soft bowel motion. Abdominal discomfort declined over the next one to two days. Physical examination including sigmoidoscopy with rectal biopsy, blood screen, ESR, electrolytes, and renal, liver and thyroid function tests were all normal. No bacterial pathogens were isolated from faecal culture. No white blood cells were seen on the faecal smear. Stool parasite examinations revealed DF trophozoites.
Dientamoeba Fragilis: a bowel pathogen? Robert Oxner et al. New Zealand Medical Journal. 11 Feb 87

A recent study described a four-year old girl who underwent a colonoscopy to investigate a history of chronic diarrhoea and the presence of mucus and leucocytes in her stools. The colon was hyperaemic and oedamatous. Biopsies revealed focal areas of eosinophilic inflitrates, and one biopsy of the descending colon revealed more than 50 eosinophils per high power field. D.fragilis trophozoites were found in the patient's stool. After treatment with iodoquinate, the eosinophilic colitis resolved and the patient remained asymptomatic for the follow-up period of 1.5 years. J.J.Windsor and E.H.Johnson. Br.J.Biomed.Sci 1999;56