46 Report of tlic Bilharzia Mission in Egjjpt, 1915 



worm ; that is, the accepted occurrence of bilharzia infection among 

 children born and bred in large towns such as Cairo, where there is 

 a filtered water supply. 



Looss states that 33 per cent, of the boys attending a school in 

 Cairo showed bilharzia eggs in the urine, and in 1908 Mrs. Elgood 

 [158] showed that out of forty girls aged 12 to 16 in a middle-class 

 school in Cairo, 11 (i.e., 27"5 per cent) were infected. These girls 

 with one exception had lived all their lives in Cairo. None had 

 ever bathed in the Nile or a canal, nor had any ever run about 



Fig. 22. — Courtyard of Department of Physical Science, Cairo, showing supply of 

 unfiltcred water pumped direct from the Nile. 



bare-legged in fields or country roads. The general water supply 

 in Cairo is the same for natives as for Europeans, is of high quality 

 and is supplied from the filters of the Cairo Water Company. 

 These facts have been repeatedly used by the supporters of the 

 Looss hypothesis, and certainly if correct could scarcely be other- 

 wise explained. 



After some inquiry the following facts came to fight, which 

 seemed to afford a simple and adequate reply to this objection. In 



