PROPHYLAXIS OF MALARIA. 
93 
proximity to this post would have very greatly reduced the amount 
of malaria among the troops at that time, as the observations upon 
the latent infections in the natives proved conclusively that much of 
the malaria existing among the troops at Camp Stotsenburg was due 
to infection received while visiting the barrios and that any efforts 
to limit the disease in the post must take this condition into account. 
It will thus be seen that latent infection among the natives in a 
country occupied by troops is a most important factor in the spread 
of malaria, and that the discovery and, if possible, the treatment 
of these infections, is necessary in the prophylaxis of the disease. 
Not only are the natives in a malarial region a source of danger 
to troops, but latent infections among the soldiers themselves furnish 
a constant menace to the health of the command. Improperly treated 
cases of the disease almost always become “ carriers ” of the infection, 
and it is just as important to recognize latent infection among the 
troops as it is among the native population. As an illustration of 
this I may mention the results of an examination of the blood of a com¬ 
pany of United States soldiers returning from the Philippine Islands 
in 1902. 
In August, 1902, Company H, Sixteenth Infantry, United States 
Army, reached San Francisco from the Philippine Islands, having 
served in the Cagayan Valley, a notoriously malarial region in those 
islands. On August 16, 1902, this company, out of a total strength 
of some 60 men, had 14 men in hospital suffering from malarial infec¬ 
tion, all having had chills since arrival in the United States. On 
account of this large proportion of sick in hospital, I believed it 
would be advisable to make a blood examination of the entire com¬ 
pany, and accordingly, on August IT and 18,1 examined the blood of 
every man on duty in Company H, with the following results: Of the 
47 men who were doing duty and were apparently in good health, I 
found that 27, or over 57 per cent, showed some form of malaria 
plasmodium in their blood. Of these 27 men, 25 were infected with 
the estivo-autumnal plasmodia and 2 with the tertian plasmo¬ 
dium. Of these men no less than 13 showed crescents or gametes , 
and were, therefore, carriers of malarial infection, while the remain¬ 
der showed the forms observed in the human life cycle of the plas¬ 
modia. It is unnecessary to discuss the importance, from a pro¬ 
phylactic standpoint, of such a body of men, should they have entered 
a territory in which anopheline mosquitoes were present but in which 
malarial infections were absent, nor is it necessary to speak of the 
importance of properly treating such infections in the prevention of 
the disease. One thing, however, should be emphasized, and that is 
that had these men been properly treated in the beginning their in¬ 
fections would have been cured and they would not have become car¬ 
riers of the disease. 
