Water in Kelation to the Spread of Bilharzia. 



With the knowledge that the infective agent of Bilharziosis is 

 the cercaria, and that this can only develop in certain molluscan 

 intermediaries, we have to consider whether anything can be done 

 to control the spread of the disease. Professor Madden, who 

 possesses, perhaps, the most intimate acquaintance of bilharziosis 

 in all its clinical manifestations, wrote in 1910 that "among the 

 Egyptian people generally there exists a widespread endemic 

 disease, responsible for much suffering and a very considerable 

 mortality among the agricultural population particularly, which 

 we, as the controlling powers of the public health of the countr}', 

 have done nothing to try and prevent."' " Only those who are 

 conversant with the habits and ways of the people are capable of 

 judging of the apparent hopelessness of the task; but it is surely 

 time that a beginning should be made with it, though along what 

 lines it is not easy to indicate." 



It was hoped by the authorities in Egypt that the preventive 

 measures now being applied to ankylostomiasis would also prove 

 efficacious in dealing with bilharziosis. These comprise free 

 treatment, the introduction of conservancy, and the dissemination 

 of knowledge of the disease amongst the natives. Such measures 

 would appear, however, to be of little value in the control of 

 bilharziosis, for the following reasons : — 



(1) In ankylostomiasis treatment not only rapidly cures the 

 individual patient, but by killing the adult parasites also assists 

 in limiting the spread of the disease. In bilharziosis there is no 

 recognized treatment other than merely palliative. 



(2) In ankylostomiasis the disease is spread by the faeces only. 

 In bilharziosis both urine and faeces would require control. The 

 introduction of conservancy would not necessarily ensure the 

 immunity of canals and the smaller streams of water from con- 

 tamination with urine in agricultural districts. 



