PART I. INCIDENCE 29 



hospital cases, on account of their frequently liquid stools with their 

 flushing properties, gave a much lower figure. It should be 

 remarked here that many of the hospital cases which gave a nega- 

 tive result when the stool was liquid gave a positive result later 

 when the stools became formed. As the figures are those resulting 

 from the single examination, the findings of subsequent examina- 

 tions were not included. 



The presence of such a large number of carriers amongst healthy 

 men was not suspected, and came as a somewhat startling revela- 

 tion. The percentage was highest amongst the British troops in 

 the case of cooks employed at Mustapha and Sidi Bishr camps. 

 It is difficult to explain why this should be so unless the flies which 

 swarm about the cook-houses are sufficient to account for it. The 

 origin of all these infections is undoubtedly the native, as shown by 

 the high figure obtained in the case of the prisoners in Hadra 

 Prison. 



The carrier problem of E. liistolytica raises many important 

 questions which will be dealt with below. 



(a) The Possibility of examining Healthy Troops, with a 

 View to the Isolation of Carriers. 



Provided there were means at our disposal for the separation of 

 all carriers, and that the examination did not involve any great 

 delay, it would undoubtedly be advisable to separate and treat with 

 emetin all carriers of E. histolytica. At the present time, however, 

 such a course is absolutely out of the question, for we not only have 

 no means for undertaking examinations on such a scale examina- 

 tions which are often difficult even for a practised observer but it 

 would be quite unjustifiable to detain such a large number of 

 healthy men for the time required for examination and treatment. 

 Even supposing that all the carriers amongst the troops were 

 separated and treated in a country like Egypt, we are no better off, 

 for the source of infection is always present in the shape of the 

 native and the fly, with their insanitary habits. In the Alexandria 

 district the course was adopted of examining all the cooks employed. 

 This involved a great amount of laborious work which was 

 admittedly incomplete, as only a single examination was made. 

 Still, this was a distinct advantage, as all the carriers which were 

 thus identified were separated, and most of them were cured by 

 emetin treatment. There was nothing, however, to prevent the 

 men re-infecting themselves, and in order permanently to keep 

 down the number of carriers amongst any group of men it would 



