PART III. TREATMENT 109 



General Considerations as regards Treatment. 



(a) Is the Object of Treatment to destroy the Cysts or the Amoeba 

 or both f In the treatment of cases of E. histolytica infections 

 there is often supposed to be a difference between the carrier case 

 passing cysts and amoebae in a comparatively normal stool and the 

 acute case passing only amoebae in the dysenteric stool. The idea 

 has arisen from the notion that the cysts are more resistant than 

 the unprotected amoebae. It is a fact that the cysts are more 

 resistant, but this has really no bearing on the question of the 

 treatment. As has been explained above there is no real difference 

 between the carrier and the acute case, the two conditions being 

 merely different stages of the same disease. The cysts of E. 

 histolytica are formed by amoebae which are living about the ulcers 

 in the large intestine, and when once a cyst has been produced it 

 has no more influence on the course of the infection. A cyst cannot 

 rupture and liberate its amoebae in the large intestine. For this to 

 happen it has to find its way to the small intestine where it can 

 come under the action of the pancreatic fluid, and this it cannot 

 do unless it escapes from the intestine and is ingested by another 

 or the same host. This being the case it would probably be a very 

 good thing for an infected individual if all the amoebae in the 

 intestine could be induced to encyst, for they would then have no 

 course open to them but to pass out in the fasces. 



In treating cases of E. histolytica infection it is, fortunately, not 

 the resistant cysts we have to deal with, but the free amoebae which 

 must be present in the gut if the cysts are found in the stool. The 

 cysts in fact are very useful guides as an indication of the extent 

 of the amoebic infection of the gut in just the same way as the 

 number of ankylostoma eggs is an indication of the number of 

 worms present in the small intestine. In treating an ankylostome 

 infection one does not endeavour to destroy the eggs in the intes- 

 tine any more than in treating an E. histolytica infection one tries 

 to destroy the cysts. In both cases, the eggs and the cysts are 

 conveniently searched for in the stool to estimate the effect of any 

 course of treatment aimed at the destruction of the worms and the 

 amoebae respectively. We have dwelt upon this point because we 

 have so often heard it stated that some cases of E. histolytica 

 infection will not respond to treatment, merely because the resistant 

 cysts are present in the gut. This view is entirely disproved from 

 the results we have obtained by emetin treatment, and one of these 

 cases (Smith) who relapsed repeatedly never passed cysts at any 



