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a genus of flagellate protozoa parasitic in birds and mammals, including humans. T. ho´minis and T. te´nax are nonpathogenic species found in the human mouth and intestines. T. vagina´lis is found in the vagina and male genital tract and is the cause of trichomoniasis.
Schematic diagram of Trichomonas vaginalis. From Brunzel, 1994.


(trik'ō-mō'nas, trik'ō-mon'as), Although the correct pronunciation of this word is trichom'onas, the pronunciation shown is more commonly heard in the U.S.
A genus of parasitic protozoan flagellates (subfamily Trichomonidinae, family Trichomonadidae) causing trichomoniasis in humans, other primates, and birds. Specificity is more marked for its precise microhabitat than for host species. The genus has been divided into several genera: Trichomonas, Pentatrichomonas, Tetratrichomonas, and Tritrichomonas.
[tricho- + G. monas, single (unit)]


/Tricho·mo·nas/ (-mo´nas) a genus of flagellate protozoa. It includes T. ho´minis, a nonpathogenic human intestinal parasite, T. te´nax, a nonpathogenic species found in the human mouth, and T. vagina´lis, the cause of trichomoniasis.trichomo´nal


a genus of flagellate protozoa that includes many species that are parasitic. Some live in the mouth of humans and are found around carious teeth. Other species are found in the vagina and urethra of women. They are a cause of trichomoniasis.


A genus of parasitic protozoan flagellates causing trichomoniasis.
[tricho- + G. monas, single (unit)]


(trik?o'mo'nas) [? + monas, unit]
Genus of flagellate parasitic protozoa.

Trichomonas hominis

A benign trichomonad found in the large intestine.

Trichomonas tenax

A benign trichomonad that may be present in the mouth.
Enlarge picture

Trichomonas vaginalis

A species found in the vagina that produces discharge. T. vaginalis is fairly common in women, esp. during pregnancy or following vaginal surgery. It is sometimes found in the male urethra and may be transmitted through sexual intercourse. See: illustration; colpitis macularis


T. vaginalis causes persistent burning, redness, and itching of the vulvar tissue associated with a profuse vaginal discharge that may be frothy or malodorous or both. Occasionally, infection with T. vaginalis is asymptomatic.


Metronidazole (Flagyl) is taken orally by the woman and her sexual partner. The drug is contraindicated during the first trimester of pregnancy because of potential damage to the developing fetus; clotrimazole vaginal suppositories provide symptomatic relief during the first 12 weeks of gestation.


Alcohol should not be consumed during metronidazole therapy.


a genus of parasitic protozoan occurring in the digestive and reproductive systems of humans and many other animals.


a genus of flagellate protozoa parasitic in animals, birds, and in humans. Member of the family Trichomonadidae and characterized usually by the presence of a single flagellum.

Trichomonas caballi
found in the colon of horses.
Trichomonas canistomae
found in the mouth of dogs.
Trichomonas equi (syn. Trichomonas faecalis)
Trichomonas equibuccalis
found in the mouth of horses.
Trichomonas felistomae
found in the mouth of cats.
Trichomonas foetus
see tritrichomonasfoetus.
Trichomonas gallinae
found in the upper digestive tract of many birds but mostly in pigeon squabs where it causes avian trichomoniasis.
Trichomonas gallinarum
see tetratrichomonasgallinarum.
Trichomonas hominis
see pentatrichomonashominis.
Trichomonas intestinalis
see pentatrichomonashominis.
Trichomonas macacovaginae
found in the vagina of the rhesus monkey.
Trichomonas phasioni
causes diarrhea and dehydration of pheasant poults.
Trichomonas tenax
found in the mouth of monkeys and humans but has no pathogenic effect.