i88 RESEARCH IN PROTOZOOLOGY 



tions with Endaina:ba Jiistolytica and Endani<rba nana; two with 

 Endamccba Jiistolytica, Endama^ba nana, and Endamwba coll; two 

 with Endamccba histolytica and Chilomastix mesnili; and two with 

 Endamoeba histolytica and Giardia intcstinalis. Forty-five of the 

 positive cases showed a pure infection with Endainceba histolytica. 



Clinically, over sixty-five per cent of the individuals giving a 

 positive reaction presented symptoms that were probably caused 

 by the parasite, while in the remainder, if symptoms had been 

 present they were not noted by the patients. In other words, 

 these latter individuals were so-called ''healthy carriers" of E. 

 histolytica. 



The large percentage of positive reactors presenting symptoms 

 is accounted for by the fact that they were mostly hospital pa- 

 tients suffering from gastro-intestinal symptoms or in hospital for 

 other conditions, and many of them had a history of amoebic dysen- 

 tery. In practically all of the patients presenting symptoms of 

 the infection, who gave a positive reaction, proper treatment which 

 caused a disappearance of the amoebae from the stools resulted in 

 the disappearance of the symptoms, and also in a disappearance 

 of the positive reaction within from three to six weeks after 

 treatment in all who were tested. 



Of the 509 individuals whose blood sera gave a negative reaction 

 with the complement fixation test, an examination of the feces 

 resulted in the discovery of only five infections with E. histolytica, 

 or about 0.9%. It is interesting to note that in these cases the symp- 

 toms of amoebic dysentery were very acute and amoebic abscess 

 of the liver was present in one case. Among the 509 individuals 

 giving a negative complement fixation test 144, or 28.2%, showed 

 the presence in the feces of some other species of protozoa. There 

 were sixty-seven individuals, or 13.2%, with Endamoeba coli in the 

 feces ; forty-one, or about eight per cent, with Endamccba nana in 

 the feces; three, or approximately one-half of one per cent, with 

 lodamocba zmlliamsi; seventeen, or 3.3%, with Chilomastix mesnili; 

 eleven, or 2.1%, with Trichomonas hominis; and five, or approxi- 

 mately one per cent, with -Giardia intcstinalis in the feces. There 

 were eleven mixed infections with Endamoeba coli and Endamoeba 

 nana; four with Endamoeba coli and Chilomastix mesnili; three 

 with Endamoeba coli and Giardia intcstinalis, and one with Enda- 

 moeba coli and Tj'ichomonas hominis. In iii of the cases giving a 

 negative complement fixation reaction, or 21.6%, some other species 



