STATISTICS OF HUMAN INTESTINAL AM(EB^ 



259 



nana, to which they bear some resemblance. Though these cultural 

 amoebse resemble one another superficially, they belong to several distinct 

 species. They can be differentiated fropi one another by a careful study 

 of the nuclear division and the encysted stage. The amoebse isolated in 

 this way are usually species of HartmayineUa and Dimastig amoeba. The 

 shelled form Chlamydophnjs stercorea and its allies may also occur on agar 

 plate cultures of faeces of animals. 



STATISTICS OF INTESTINAL AMCEB^ OF MAN. 



As in the case of most of the parasitic infections of the intestine, the 

 incidence of amoebic infections in any community is directly related to 

 the efficiency or otherwise of the sanitary arrangements. Where there 

 is every possibility of food and water becoming contaminated with fsecal 

 material, either directly, or indirectly by the agency of flies, there the 

 percentage of individuals harbouring intestinal Protozoa will be high. 

 It was shown by the writer and O'Connor (1917) that flies in Egypt are 

 constantly feeding on fsecal material, and that the cysts of intestinal 

 Protozoa, and even the unencysted forms, may quickly pass undamaged 

 through the intestine, and in this way be deposited on food. 



It is probably correct to state that all the intestinal amcebde of man 

 are world-wide in their distribution, the number of individuals actually 

 infected varying with the locality. In tropical countries, where sanita- 

 tion is generally bad, the incidence is high, while in England it is relatively 

 low, though even here the figures are higher than might be expected. 

 It has already been pointed out that the percentage of infections resulting 

 from a single examination of each case is fallacious, and that repeated 

 examinations usually yield a figure which is at least three times as great 

 as that obtained by a single examination. In Alexandria and London 

 during the war the writer and O'Connor (1917) found the following 

 percentages of infection amongst different groups of men: 



