56 Bej)ort of the Bilharzia Mission in Egypt, 1915 



The rainfall in Egypt is at no time enough of 

 Eainfall. itself to moisten the soil sufficiently for agricultural 

 use, and is confined to the winter months from 

 October to April. As will be seen from the accompanying table, 

 no rain was recorded from any part of Egypt during the months 

 of June, July, August, and September. Mr. Hurst, of the Physical 

 Science Department of Egypt, has examined the official records for 

 the last twenty years, and has found that an absence of rain during 

 these months has been constant. 



The average rainfall per annum at Cairo during the last nine- 

 teen years is only 3'28 centimetres. Willcocks and Craig estimate 

 that the amount of the Nile water used on the Delta to irrigate the 

 crops corresponds approximately to a rainfall of 1"30 metres, i.e., 

 fifty-one inches per annum. 



Protective Measures. 

 The life of the bilharzia outside the body may be divided into 

 three periods : (1) That between the passage of the egg into water 

 and the entrance of the hatched parasite into the mollusc ; (2) the 

 stage of metamorphosis within the mollusc ; (3) that prior to the 

 entrance of the free-swimming cercaria into the human body after 

 it has left the mollusc. It is universally recognized that in Egypt 

 under present circumstances it is practically impossible to prevent 

 the contamination of water with infected urine and faeces. In 

 order to break the life-cycle of the bilharzia worm one must find 

 some simple means of destroying it during the free-swimming 

 infective stage, or of depriving it of its essential intermediate host. 



