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Malaria. 
In its many phases malaria is unquestionably the most serious 
adversary 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 intercurrent affections such as dysentery and 
ankylostomiasis. Malaria is conveyed to man through the bites of 
anoplieline mosquitoes, several 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 purposes all anophelines must be taboo, no 
effective measures for their extermination or reduction should be 
neglected. We do nob know very much about tlie 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 great 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 
prophylaxis, oiling, and piping. One or other measure may be all 
that is necessary 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 are 
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 ravines, a very effective means for the 
destruction of mosquito larvse. 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 
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