39 



CHAPTEE IV. SUMMARY OF ALL REPOETS, AND DIS- 

 CUSSION OF CERTAIN POINTS OF PARTICULAR 

 INTEREST. 



In this chapter I propose to corabine and discuss the results 

 obtained by all the workers concerned in the present investigation. 

 I shall begin with a consideration of the incidence of infection 

 with the various protozoa studied. 



A. The Incidence of Protozoal Infections in Persons who have 

 never left Britain. 



There is now a fairly large accumulation of statistics bearing 

 on this subject, and it is therefore now possible to estimate the 

 probable incidence of several different protozoal infections with 

 some precision. In order to arrive at a just estimate of the 

 results as a whole it will be necessary, in the first place, to add 

 together the findings recorded in the several Reports. 



The findings of Smith and Matthews are mostly presented in 

 the form of percentages ; and I have therefore worked out their 

 actual figures in order to be able to combine them with those of 

 the later workers. I have thought it necessary, for the present 

 purpose, to exclude the results recorded by them for asylum 

 patients. The people of this category are in several ways not 

 fair samples of the population, and there is reason to suppose 

 that their habits and mode of life are conducive to the acquisition 

 of intestinal infections to an abnormal extent. Excluding, there- 

 fore, the mental eases examined by Matthews and Smith (1919 a) 

 and Smith (1919), I have obtained the following figures from all 

 the Reports published by the Liverpool workers : 



This table gives the actual numbers of persons found infected 

 with intestinal protozoa in the four series of cases investigated by 



' In this and the two subsequent tables the following abbreyiations are used for 

 the names of the intestinal protozoa which come into consideration : 

 -E. !>, = Entamoeba histolytica. 

 E. 0. = En'amoeba coli. 

 E. n. = Endolimax nana 

 I. b. = lodamoeba biitschlii. 

 G. i. ~ Qiardia intestinalis. 

 Ch. m. = Ckilomasfix mcsnili. 



