no DISEASES DUE TO PROTOZOA 



tends to diminish at 500 — 1,000 feet high, but under suitable conditions 

 it may be found 5,000 feet high. 



(9) Rice should not be cultivated within five miles of towns in 

 Italy because of the swampy nature of the ground. In India, however, 

 where this law would mean famines it could not be enforced. 



Professor Pearson has worked out an interesting point on mosquito 

 reduction. Me affirms that if moscjuito propagation is suppressed 

 within the circular area of a mile — 



The mosquito density at the centre will be 3 per cent. 



At a quarter of a mile from the centre 18 per cent. 



At the periphery 75 per cent, of the density surrounding that area. 



Sir Ronald Ross's work at Ismailia reduced malarial cases from 

 1,551 in 1902 to 37 in 1905, the latter being all relapses. The cost of 

 the work was 2 — 3 francs per head of the population. 



Every malarial district before being opened up should be systematic- 

 ally surveyed with regard to malarial propagation, and the work 

 commenced at once on given lines. 



Celli has shown us some interesting figures on the 



Relative Values of Malarial Prophylaxis. 



Protection Quinine and 

 Method of prophylaxis None Qjinine alone from mosquito protection 



alone from mosquito 



Percentage of infection ... 33 ... 20 ... 2*5 ... 175 



Hence quinine alone will prevent 13 per cent, of cases, and 

 Quinine plus mosquito protection will prevent 3r25 per cent, of 

 cases. 



FOR NEW INFECTIONS ARE REQUIRED:— 



(i) That an infected person with gametocytes is living in or near 

 to the locality. 



(2) That an Anopheles, capable of carrying" such gametocytes,. 

 sucks up sufficient blood from the infected person. 



(3) That this mosquito lives for a week or more under suitable 

 conditions. 



(4) That it then bites a person non-immune and not protected by 

 quinine. 



(5) Infected persons and carrying flies must be sufficientlv 

 numerous. If there are many flies and few infected persons the 

 chances of becoming infected are greater than if there were few flies 

 and many infected persons. 



The following facts may be of interest : — 



Spleen Rate. 



Within 300 yards of jungle, undrained, it was 47 per cent. 



