TRANSAIISSION OF INTESTINAL PROTOZOA n 



transfer human vaginal trichomonads to dogs, rabbits and guinea- 

 pigs have been unsuccessful (Blockmann, 1884; Dock, 1894). 



TRANSMISSION OF Trichomonas hom'mis in the trophozoite 



STAGE 



No cysts are known in the life-cycle of this intestinal flagellate, 

 hence it must be transmitted in the trophozoite stage. The only 

 conceivable method of reaching the intestine appears to be by the 

 fecal contamination of food or drink that is ingested by the host. 

 The first question that arises is whether trophozoites are able to 

 withstand the action of the digestive juices during their passage 

 through the stomach and small intestines. It has been proved that 

 Trichomonas muris is able to do so in the rat and there is every 

 reason to believe that Trichomonas hom'mis can in man (Hegner, 

 1924). Material containing T. muris was taken from the cecum of 

 the rat, diluted with normal saline solution and injected into the 

 stomach of other rats by means of a hard rubber catheter attached 

 to a syringe. These rats were killed at intervals and it was found 

 that trophozoites of this species are capable of remaining actively 

 motile for at least one hour after being injected into the stomach 

 of the rat ; that they may pass from the stomach into the duodenum 

 apparently unharmed within half an hour; that they may reach 

 the cecum through the stomach and 780 millimeters of small intes- 

 tine within half an hour and still be actively motile; and that a rat 

 free from trichomonads may acquire a cecal infection within four 

 days after trophozoites are injected into the stomach. Later ex- 

 periments (Hegner, 1926) prove that the trophozoites of Trichom- 

 onas cavico and T. Hagelliphora of the guinea-pig are able to pass 

 through the stomach and small intestine of a guinea-pig and reach 

 the cecum apparently unharmed within an hour after being in- 

 jected into the stomach. Other investigators have recently con- 

 firmed these results. Thus Brumpt (1925) has reported the 

 infection of cats by the ingestion of trophozoites of Trichomonas 

 felis and Wenrich and Yanofif (1927) have shown that four species 

 of rat trichomonads and one species from man may likewise be 

 infective to rats in the trophozoite stage. 



The next problem is whether Trichomonas hominis is able to 

 live outside of the human body in fecal material long enough for 

 food and drink to become contaminated. A number of experiments 

 bearing on this problem were carried out by the writer (Hegner, 



