PATHOGENICITY OF TRICHOMANAS 121 



slides. It is the opinion of many protozoologists, however, that 

 these so-called cysts are really degenerate forms, and that cyst 

 formation has not yet been satisfactorily demonstrated. Lynch 

 and others have succeeded in cultivating Trichomonas and in 

 infecting rabbits with it, but specimens cannot be kept alive in 

 water or faeces for more than a few days under the most favorable 

 conditions. 



Trichomonas is generally regarded as a harmless parasite, but 

 there seems to be strong evidence that it often causes diarrhea, 

 sometimes very severe and of long duration. Epidemics of 

 diarrhea and mild dysenteric symptoms in man apparently caused 

 by Trichomonas have been reported from Peru, Brazil, China, 

 South Carolina and Indiana, and it is probable that the parasite 

 is at least mildly pathogenic wherever it occurs, tending to ag- 

 gravate other intestinal ailments if not causing them directly. 

 Haughwout suggests the following possible ways in which this 

 parasite may damage its host: (1) production of growth-inhibiting 

 substances; (2) production of substances directly toxic; (3) 

 liberation of injurious metabolic products; (4) mechanical ir- 

 ritation of mucous membranes; (5) interference with absorption 

 by adherence to intestinal walls; (6) invasion and destruction of 

 tissues. On the other hand Wenyon and O'Connor regard the 

 presence of Trichomonas in cases of diarrhea as usually accidental, 

 and fixed upon as the cause because the most conspicuous or- 

 ganism present. A case has recently been reported of an Oriental 

 who was suffering from a foul-smelling decay of the jaw, accom- 

 panied by pains in the joints, in which numerous Trichomonas 

 were found in the jaw lesion. After treatment with emetin there 

 was rapid improvement, which suggests that Endamoeba may 

 also have been present. 



No specific drug for use against Trichomonas has yet been 

 found. Methylene blue in weak solutions is absorbed by the 

 parasites and causes them to become round and quiet. Castellani 

 recommends taking methylene blue both by mouth and by means 

 of an enema, i.e., irrigation of the large intestine. With this 

 treatment the flagellates are said to decrease rapidly and to disap- 

 pear usually within a few days. Escomel, who has found Tri- 

 chomonas an important factor in diarrhea in Peru, advises an 

 enema consisting of one grain of iodine in a liter of water, taken 

 in the evening on three successful days. Unless the parasites 



