9 6 



I think it would be advisable to attempt to obtain in Sierra Leone 

 some numerical estimate of the present prevalence of malaria, and for 

 this purpose suggest as the most convenient the estimation of the 

 proportion of children with splenic enlargement at fixed ages, say 

 between one and two years of age, as, up to two or three years, reliable 

 statements as to the age of children can generally be obtained. As a 

 check on this method, Barbadians in the West India regiment who 

 have not been previously exposed to malaria, and consequently are 

 highly susceptible, should be examined. In them malarial infection 

 is indicated by malarial fever. The length of residence in Sierra 

 Leone requisite for malarial infection in the Barbadians will then give 

 an indication of the present liability to infection.* 



In conclusion, I wish to express my thanks to you personally, and 

 to the Liverpool School of Tropical Medicine, for the opportunity 

 afforded me of seeing the first real British practical application of the 

 principles you have elucidated. 



I am, 

 Yours very sincerely, 



C. W. DANIELS, M.B., 



London School of Tropical Medicine. 



* In order to guard against misapprehension, it is advisable to state here that 

 we are not now undertaking to prove over again that mosquitoes carry malaria. 

 This fact was fully established long ago. Our present intention is simply to give 

 an object lesson in the manner of ridding tropical towns of mosquitoes by drainage 

 and cleaning up. We are prepared to spend a large sum of money for this 

 purpose ; but we are not prepared to continue the work for ever. The work- 

 especially the drainage and collection of rubbish properly belongs to the local 

 authorities. If they choose to continue our efforts, then we can confidently promise 

 that the mosquito-borne disease in Freetown will be, ultimately, very materially 

 reduced. If, however, they discontinue them if they allow the town to sink back 

 into the condition it was in when we arrived then I can only say that the 

 mosquito-borne disease will remain. It is for them to choose. I may add, how- 

 ever, that I have no doubt that the former course will be the one adopted. 



Original Note, 



