144 HUMAN INTESTINAL PROTOZOA IN .THE NEAR EAST 



0-001, 0-0005, 0-0003, O'OOl, O'OOl, 0'0027, 0-0024. This gives an 

 average of O'OOl gramme per fly. It may be assumed, therefore, 

 that a single fly which has not fed for two or three hours can take 

 up one milligram of faeces in half an hour. 



General Considerations. 



In our former communications we have emphasized the influence 

 of the house-fly as a disseminator of infectious material. The 

 experiments show how readily this is done, for a fly which is 

 constantly feeding is constantly passing material through its gut, 

 and this may be accomplished in five minutes as proved by 

 the trichomonas experiment recorded above where the living 

 flagellate was found in the droppings of the fly five minutes after 

 feeding. It is quite evident that as the unprotected flagellate can 

 pass safely through the intestine of the fly encysted stages of 

 protozoa will do so much more easily. In fact, one can safely 

 assume that all such organisms, including bacteria, will in such a 

 short time pass undamaged through the fly's intestine. This being 

 the case, it seems that the fly is much more dangerous on account 

 of material passed through its intestine directly than on account 

 of material which it may regurgitate, or which has become adherent 

 to its legs or body, where it quickly dries and is in most cases 

 quickly destroyed. There is no question of any development in the 

 gut of the fly, which acts merely as a distributor of infectious 

 material. In warm countries there is great danger from this, for 

 these flies abound, and there the insanitary native is in league with 

 the flies, for, by depositing his faeces indiscriminately in the open,- 

 he not only supplies infectious material for the flies to feed upon, 

 but at the same time affords them a breeding-ground wherein they 

 can lay their eggs. 



We have shown above by the record of our examination of 

 natives in the Hadra prison and of a small number of human faecal 

 deposits collected in the open how common are protozoal infections 

 amongst the natives, and it is not to be wondered at that we have 

 found such a comparatively large number of infected flies, especially 

 when it is remembered that these flies had probably been feeding 

 previously in the native village. In these countries flies must be 

 constantly taking up material and depositing it upon food, and it 

 seems to us that the wide distribution of the intestinal protozoal 

 infections amongst the natives can more readily be accounted for 

 in this way than any other. It is probable also that other intestinal 

 disorders are spread in a similar manner. 



