Fig. 16.—Trichomonas vaginalis, Donné. × 2,000 approx. (After Künstler.) Four flagella are represented, but usually only three are present.
T. vaginalis appeared to be a parasite specific to the female organs and not transmissible to man. However, several observations have since been made that confirm the occurrence of this species in the urethra of the male. The infection apparently takes place through coitus when changes are present in the urethral mucous membrane. At any rate, three cases observed point to this circumstance.
Attempts at experimental transmission to rabbits, guinea-pigs and dogs failed (Blochmann, Dock). So far, the manner in which women become infected is unknown.
Trichomonas intestinalis, R. Leuckart, 1879 = Trichomonas hominis, Davaine, 1854.
Some authors believe that a second trichomonad inhabiting man, Trichomonas intestinalis, R. Lkt., is identical with Trichomonas vaginalis, Donné. Leuckart’s species was based on the discoveries of Marchand (1875) and Zunker (1878), who stated that according to all appearances, and in their opinion, it was the same as Cercomonas intestinalis, Lambl, 1875 (nec 1859), which they found in the fæces of patients suffering from intestinal disorders. The organism is described by them as being pear-shaped and 10 µ to 15 µ in length and 3 µ to 4 µ in breadth. The posterior extremity terminated in a point (fig. 17).
Fig. 17.—Trichomonas intestinalis, Lkt. (After Grassi.)
A row of twelve or more cilia was said to commence at the anterior end and extend over the body. Leuckart stated that this parasite, placed by the two authors in the genus Cercomonas, was a Trichomonas, and that they mistook the undulating membrane for cilia, and overlooked the flagella. Notwithstanding its striking similarity with T. vaginalis, it was said to be distinguishable from that species by differences in the undulating membrane. Lambl’s C. intestinalis[38] (of 1875) which corresponds with C. hominis, Davaine[39] (1854), is regarded by Leuckart as a true Cercomonad (characterized by a flagellum and the absence of an undulating membrane, see p. [61]), and is thus generically distinct from Trichomonas.