The question of the effects, if any, upon the host of the presence of Trichomonas hominis in the human intestine is still a subject of question and debate.
Observations of actual invasion of the wall of the intestine or of its presence beyond the intestine whereby it may be assumed to have escaped from its habitat in the lumen are very rare.
Wenyon (1920) studied 5 cases of Trichomonas infection by examining the intestinal content for the flagellates and searching Zenker fixed sections of the wall of the infested portions for them. In none of these cases (in all of which death was due to pneumonia) was there any noticeable lesion which one could attribute to the flagellates.
Histological sections showed the trichomonads to be distributed over the surface of the mucosa. The flagellates were also found in the lumen of the glands of Lieberkuehn, in large numbers in some.