188 PROTOZOAN PARASITISM 



school age found that of the 47.2% infected with 

 Giardia intestinalis, 57.6% had chronic or recurring 

 diarrhoea, as compared to a similar history in only 

 24.2% of the flagellate-free, and in M.^% and 27.9%o 

 of the carriers of Chilomastix viesnili and Trichom- 

 onas hoinmis, respectively. 



Zahorsky (1928) is convinced of the production of 

 intestinal disturbance in children. 



The very common occurrence in children, especially 

 under crowded conditions, without any evidence of 

 the production of any disturbance, brings serious 

 question as to whether it ever causes trouble. It is 

 most common between the ages of one and ten years 

 and this is the period when intestinal upsets are most 

 apt to occur. Merely its presence in a case of diar- 

 rhoea or dysentery does not prove it to be a patho- 

 genic factor. 



There is, however, a very strong belief in the medi- 

 cal profession that giardiasis signifies a state of up- 

 per small intestine irritation with ''indigestion" and 

 chronic or recurring diarrhoea, with mucous, but 

 never bloody, stool, occurring particularly in young 

 children. Such studies as that of Hill and Hill (1927) 

 showing diarrhoea conspicuous, much beyond the con- 

 trols, is strong evidence in support of this belief. 

 Similar repeated studies with like results would go 

 far toward establishing the pathogenicity of the or- 

 ganism in a definite clinical syndrome. From a 

 working viewpoint it is, perhaps, not unwise or un- 

 reasonable to assume that such a condition occurs, 



