SCHISTOSOMIASIS 



249 



Surgical treatment for calculus and fistula as rec(uired. 



All stimulants and excesses must be avoided. 



Prohibit micturition and defiecation inlo Mnler; boil and filter all 

 drinking water. 



The mortality is low. Amongst affected Europeans removed from 

 the endemic area less than i per cent. die. 



The recent Bilharzia Mission to Egypt, 1915, consisting of Drs. 

 Leiper, R. P. Cochin, J. G. Thompson, has thrown much valuable 

 light upon this subject. A few points are as follows : — 



The incubation of the disease is probably one to two months, and 

 is not as long as previously thought. 



The absence of a pharynx in the cercaria is the one reliable 

 character by which Bilharzia cercarise can be distinguished from other 

 distomas. 



Storage of water for thirty-six hours will destrov all cercariae. If 

 this was carried out with regard to the Cairo water supply alone, prob- 

 ably the 10,000 children now infected annually would be spared. 



The extension of perennial irrigation in Egvpt appears to have 

 encouraged the spread of the disease. 



Of 625 men who became infected in South Africa, 359 were still on 

 the list in 191 1, exclusive of those permanently pensioned. The total 

 cost to the State was about ;^'io,ooo per annum (Leiper). 



The conclusions arrived at by the Mission are of interest as con- 

 trasted with those of I^oos. They are shown thus : — 



Conclusions based on the Loos 

 Hypothesis. 



i,i) All transient collections of water, 

 such as those resulting from occa- 

 sional showers of rain, road water- 

 ings and domestic waste, are 

 dangerous if freshly contaminated. 



(2) Large bodies of water, such as the 

 Nile canals, marshes and birkets, 

 are little liable to be infective. 



(3) All water in a given area would 

 automatically become safe in 30 

 hours if the native infected popula- 

 tion were removed. 



(4) Infected troops would be liable to 

 reinfect themselves, to spread the 

 disease among other troops, and to 

 convey the disease to any part of the 

 world. 



Conclusions based on the Results of 

 THE Present Inquiry. 



(i) Transient collections of water are 

 quite safe after recent contamination. 



(2) All permanent collections of water, 

 .such as the Nile, canals, marshes 



and birkets, are potentially dan- 

 gerous, depending on the presence 

 of the essential intermediary host. 



(3) The removal of infected persons 

 from a given area would have no 

 effect, at least for some months, in 

 reducing the liability to infection, as 

 the intermediate hosts discharge in- 

 fective agents for a prolonged period. 



(4) Infected troops cannot reinfect 

 themselves or spread the disease 

 directly to others. They could only 

 convey the disease to others in those 

 parts of the world where a local mol- 

 lusc could efficiently act as carrier. 



