PROPHYLAXIS OP MALARIA. 
109 
learned in a short time by observations of the kind of mosquitoes 
present, the location of their breeding places, and an examination of 
the blood of from 20 to 40 children and adults in the region being 
investigated. This entire study of a location need not consume more 
than a few hours and will generally result in definite knowledge 
regarding the prevalence of malarial infection. If, despite the pres¬ 
ence of infection, the locality must be selected for a camp site, the 
measures pursued will vary, of course, with the length of time the 
camp is to be occupied and the facilities afforded for their execution. 
If the camp is to be occupied for only a few days, the prophylactic 
use of quinine, the use of the mosquito net, and the clearing of an 
area from 100 to 200 yards around the camp of long grass and under¬ 
brush will be about all that can be done in the way of prevention. 
In the case of camps that will probably last for several months and 
are, therefore, of semipermanent character, the same precautions 
should be taken regarding the selection of a site as recommended for 
permanent posts, and similar prophylactic measures should be em¬ 
ployed if malarial infection appears. 
Malaria prophylaxis in permanent posts .—Before establishing a. 
permanent military post in the tropics or in regions in which the 
presence of malarial infection is suspected, a malaria survey of the 
locality is of the greatest importance, and, in most instances can be 
made without interfering with military movements. If such sur¬ 
veys had been made before certain posts were established in the 
Philippines, it is probable that other localities would have been se¬ 
lected with a resultant saving in money and efficiency. Certainly 
there can be no excuse for establishing a military post in a very 
malarious region when a malaria survey would have shown that 
adjacent regions were free from the infection and when there was no 
military necessity for occupying exactly the locality chosen. 
The following points should be considered in estimating the safety 
of a locality as regards malaria when the question of choosing it for 
the site of a post is considered: The statistics regarding fevers in 
the locality, if there are any, should be studied; the character of the 
soil and the nature of the terrain; the species of mosquitoes present; 
the breeding places of mosquitoes and the kind of larvae present; the 
presence and number of infected mosquitoes; and the number of 
latent infections in children and adults. A map of the locality should 
be obtained, or prepared, and the entire region districted, after which 
a careful investigation regarding the points mentioned should be 
made of each district by a trained medical officer. Upon the map 
should be marked the location of breeding places of mosquitoes, the 
species found in each breedery, and whether any of the insects 
examined were found infected with plasmodia. In addition the 
dwellings of individuals found infected with malaria during the 
