Trichomonas hominis: Introduction, morphology, Lab Diagnosis, Pathology, Prevention and Control

Trichomonas hominis under microscope of stool sample

Trichomonas hominis

Trichomonas hominis is a protozoan flagellate and therefore motile organism.


It is of cosmopolitan distribution. It is thought to be non-pathogenic although it has been associated with diarrheic stools. It is the most commonly found flagellate next to Giardia lamblia and Dientamoeba fragilis.

Morphology of Trichomonas hominis

It has no cystic stage. The trophozoite measures from 5-15µm in length by 7-10µm in width. The shape is pyriform and has an axostyle that runs from the nucleus down the center of the body and extends from the end of the body and an undulating membrane which extends the entire length of the body and projects from the body like a free flagellum. It has 4 free flagella and a single nucleus at the anterior end.

Laboratory Diagnosis

In a fresh stool, the flagellates move very rapidly in a jerky, non-directional manner. The axostyle and undulating membrane are diagnostic. The flagellates are difficult to stain, however, the axostyle can be seen on a stained preparation and is diagnostic. 

Pathology, Prevention, and Control of Trichomonas hominis

Trichomonas hominis is considered a nonpathogenic inhabitant of the large intestine. Trophozoites of this may be observed in fresh smears of both normal and diarrheic fecal samples. Since this organism is nonpathogenic, efforts to eliminate or prevent infection are not usually undertaken.


  1. A textbook of parasitology, K.D. Chatterjee
  2. UK NEQAS  Parasitology
  3. Google search


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