Synonyms: Cercomonas hominis, Monocercomonas hominis, Trichomonas intestinalis, Trichomonas confusa, Pentatrichomonas ardin delteili, Trichomonas fells, Trichomonas parva, Pentatrichomonas canis auri.
Hosts: Man, gibbon, chimpanzee, orang-utan, rhesus monkey, pigtailed monkey (Macaca nemestrina), brown capuchin (Cebus fatuellus), weeping capuchin (C. apella), white-throated capuchin (C. capucinus), black spider monkey (Ateles ater), white-crested titi monkey (Callicebus amictus), Guinea baboon (Papio papio), Humboldt's woolly monkey (Lagothrix lagotricha), vervet monkey (Cercopithecus pygerythrus), dog, cat, rat, mouse, golden hamster. The primates were listed by Flick (1954).
Kessel (1928) infected kittens with trichomonads from man, the monkey and rat. Simitch (1932, 1932a, 1933) transmitted P. hominis from the rat to the cat, dog and man. Saxe (1954) transmitted it from the golden hamster to the laboratory rat and from the rat to the hamster. Simitch, Petrovitch and Lepech (1954) infected the white mouse, laboratory rat, guinea pig, ground squirrel (Citellus citellus), dog, cat and chicken with P. hominis from man.
Location: Cecum, colon.
Geographic Distribution: Worldwide.
Morphology: The following description is based primarily on Wenrich (1947) and Kirby (1945). The body is usually piriform, 8 to 20 by 3 to 14 u. Five anterior flagella are ordinarily present, altho some organisms may have 4 and a few 3. Flick (1954) found in a study of more than 13,000 individuals from 13 P. hominis strains from 13 hosts that 77% had 5 flagella, 17% had 4, 5% had 3, and 1% had 6 or more anterior flagella. Four of the anterior flagella are grouped together and the fifth is separate and directed posteriorly. A sixth flagellum runs along the undulating membrane and extends beyond it as a free trailing flagellum. The undulating membrane extends the full length of the body. An accessory filament, a costa and paracostal granules are present. The axostyle is hyaline, thick, with a sharply pointed tip but without a chromatic ring at its point of exit. The parabasal body is small and ellipsoidal. The blepharoplast is composed of 2 granules. The pelta is crescent-shaped, prolonged dorsally in a filament which passes posteriorly in the cytoplasm dorsal to the nucleus. A cytostome is present. There are 5 or 6 chromosomes.
Cultivation: P. hominis is readily cultivable in the usual trichomonad media.