ETIOLOGY OF MALARIAL FEVER JI 



malaria in Italy, and transported to London. These fed 

 on two uninfected persons there and these persons then 

 developed malaria. 



(3) It has been further shown that people can live in 

 malarial, swampy country, such as the Campagna, and 

 that so long as they are protected from bites of mosquitoes 

 they will be free from malaria, though other inhabitants 

 suffer. 



(4) Certain islands in the Tropics are free from malaria, 

 though neighbouring islands in sight are intensely 

 malarious, e.g., Barbados is free from malaria, whilst 

 in St. Vincent it is abundant. It is found that in the 

 malaria-free island no mosquitoes capable of carrying 

 malaria exist, whilst in others they are common. Fiji 

 may be quoted as an exception as there is no malaria 

 there, and amongst the many mosquitoes sent from that 

 country one wing of an anopheline was found. No other 

 specimens have been found, though they have been 

 looked for. 



(5) The success of anti-malarial operations which 

 diminish the liability to be bitten by malaria-carrying 

 mosquitoes by diminishing the number of those 

 mosquitoes is an additional proof of the correctness of 

 the hypothesis. In places, such as Ismailia and Kwala 

 Klang, where the reduction in the number of these 

 anophelines was great, the cases of malaria diminished 

 to one-tenth or less. In many other places where the 

 reduction in the number of these mosquitoes was less, 

 there \vas still a decided diminution in the amount of 

 malaria. 



(6) In many parts of Africa the liability to malarial 

 infection in the settlements is very closely related to the 

 actual number of mosquitoes capable of being malaria- 

 bearing. 



It is often urged that although this is one way in which 

 malaria is caused, there may be others. It is possible 

 that in other blood- sucking insects a similar development 

 of the parasites might take place, but there is no evidence 



