Dientamoeba fragilis

Diagnostic Form:

There is no cyst form of Dientamoeba fragilis.

Trophozoites can be seen in trichrome stained stool concentrate smear preparations. Trophozoites are 9-12 ┬Ám in length. They have angular pseudopods that can seem to be ragged in appearance or broadly lobed. They are sometimes difficult to discern in stained preparations when read by inexperienced technologists as they stain delicately and at times various areas appear invisible. There are generally two nucleus visible when stained, though single nucleated trophozoites are not uncommon. There is no chromosomal chromatin present. The cytoplasm of the trophozoite is finely granular and contains bacteria along with on occasional red blood cell. The karyosomal chromatin can appear as a large cluster of 4-8 granules.


d_frag d_frag1 d_frag2 nuclei first d_frag 2nd d_frag


Geographic Prevalence:

Widespread. There is a 10% prevalence in industralized countries.


Disease It Causes And The Clinical Symptoms:

Dientamoeba fragilis causes the disease Dientamoebiasis. Clinical symptoms include abdominal pain, fever, weight loss, and diarrhea.


Location In The Host:



Primary Vector:

None. Acquired by the ingestion of water and food that is contaminated with feces.


Life Cycle:





Test Recommended For Detection/Diagnosis:

Ova and parasite examinations are the best method for detecting Dientamoeba fragilis. Since there is no cyst stage, the concentration and observation with Lugols Iodine stain will not detect the organism. Stained preparations of the specimen are useful however in detecting the trophozoites.