129 



Malabia. 

 In its many phases malaria is unquestionably the most serious 

 advereary of the planting interests. It is the one disease which 

 permanently cripples a labour force. When it does not kill outright 

 it may so reduce the vitality and physique of the coolies that they 

 fall ready victims to intercui-rent affections such as dysentery and 

 ankylostomiasis. Malaria is conveyed to man through the bites of 

 anopheline mosquitoes, sevei^l species are known to be malarial 

 carriers. It is probable as our knowledge advances that other 

 species not at present known to carry infection will be found to be in 

 fact capable of so doing. 



For practical pui'poses all anophelines must be taboo, no 

 effective measures for their extermination or reduction should be 

 neglected. We do not know very much about the habits and 

 capabilities of anophelines and for that reason it is unwise to 

 dogmatize as to the best methods to be adopted to control them. 

 We do know that in Panama anophelines have been found to be swift 

 and strong on the wing and to cover gi'eat distances against or even 

 at right angles to the wind in order to obtain human blood. It seems 

 certain also that they avoid strong light, especially bright sunshine. 



Conditions are so varied that no single system of anti-malarial 

 measures can be laid down as applicable to all estates. Apart from 

 a judicious choice of line sites, already referred to, there are three 

 principal measures that may be mentioned, these are quinine 

 pi-ophylaxis, oiling, and piping. One or other measure may be all 

 that is necessai'y but it will commonly be found that a combination 

 of two at any rate is indicated. 



The regular medication by quinine over a prolonged period to an 

 estate labour force is no easy matter. It can be relied upon to 

 be effective only when the distribution is under the direct supervision 

 of a manager or assistant. It is a common experience to be told 

 that all labourers get quinine daily and to find that actually only 

 those complaining of fever get quinine and that they get it only so 

 long as they are sick. Where malaria is prevalent the children ai'e 

 certainly infected, it is therefore imperative that they and also the 

 " dependants " should be given the quinine ration. ^ 



The spraying of mosquito breeding grounds by means of an oil 

 vapour is becoming more popular, it is, when combined with the 

 clean weeding of streams and i-avines, a very effective means for the 

 destruction of mosquito larvae. In addition it is a method which has 

 the advantage that it is easily extended at a small additional cost. 

 Oil spraying is certainly the most generally suitable measure of 

 mosquito reduction upon estates and rural areas. 



The plan of conducting under ground all surface water is 

 without doubt the ideal one for the 'abolition of malaria. The 

 success of this system is, however, beset by many difficulties. It is at 



