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In these huts men from all parts of China, India or the Malay Penin¬ 
sula, slept crowded together without any protection against mosquitoes. 
Our statistics here show that adult Chinese are not immune to any 
form of Malaria any more than adult Europeans, Asiatics, Americans or 
Africans are unless reared and living in a badly malarious district. 
Most of the men are Chinese highly susceptible to Malaria, and 
amongst them will always be some who are harbouring malarial parasites. 
From these the mosquitoes, which are not numerous, become infected and 
in turn infect every susceptible person they bite. So great is the liability 
to infection that in three instances to my own knowledge a single night’s 
residence was followed in io days by an attack of Malaria. Children play 
no part in the propagation of Malaria, it is entirely a question of infected 
adults infecting, via mosquitoes, other susceptible adults, as there are 
no children at such camps. 
It will be noted that no question of drainage, filling up of pits, etc., 
can arise in connection with these mountain streams. Something might be 
done at considerable expense by clearing the course of the streams, but as 
these streams are running over masses of granite or between granite 
boulders it could not be economically undertaken for temporary stations. 
In some instances artificial obstructions to the streams are made in the 
course of felling the jungle, and portions of the streams in the vicinity of the 
huts are often dammed up for bathing and other purposes. Such practices 
should be avoided. 
Mosquito curtains in a place where mosquitoes are not troublesome 
are not satisfactory, as it is impossible to enforce their use on persons who 
are engaged for short periods only. A. Treacherii is a very small mosquito, 
and when confined in mosquito nets sometimes passes through. 
Advantage should be taken of the inability of the imago to live in dry 
air. More extensive clearings on all sides of the huts and drier houses 
will render the human habitations unsuitable for these mosquitoes. 
Such measures were partially undertaken at Gombak and for some 
months the amount of Malaria was much reduced. As the growth of the 
imperfectly cleared land recurred the returns were nearly as bad as at first. 
Work under similar conditions has been attended with very heavy 
mortality and much Malaria in many parts of the Malay States. It will 
continue to do so till good clearings are made and maintained for the labour 
employed on such works. 
The contract for such clearings and camps and the labour employed 
on the clearings and other sanitary work should be distinct from the 
contracts and bodies of men employed on the works themselves. Experience 
has shown that with the desire to expedite w r orks all available labour 
if under one authority is diverted to that work and sanitary undertakings 
are neglected. 
The second class of place of great importance is that occurring on 
extensive flat swampy areas near the coast or towards the mouths of rivers. 
Here the conditions as regards housing of labour may or may not be 
similar to the temporary camps established in the jungle. In any case 
conditions for introduction and spread of Malaria are present, and susceptible 
individuals abound. 
