PROPHYLAXIS OF MALARIA. 
89 
mation of gametes , and it will, every patient presenting these forms 
in the blood is an evidence of the improper treatment of his infection 
by his physician, provided, of course, that they were not present when 
he was first seen, as the result of a latent or very mild infection. As 
a matter of fact the vast importance of the proper treatment of the 
infected in the prophylaxis of the malarial fevers has never been 
fully realized by the profession or even by officers engaged in sanita¬ 
tion in malarial regions, for there is nothing more common, in many 
such localities, than to see gamete carriers going about their daily 
occupations without having received any advice regarding treatment 
and Avholly ignorant that they are a danger to the people of the 
community in which they reside. In much of our prophylactic work 
in the military service this phase of the subject appears to have been 
entirely overlooked and it is because of their importance in the 
prophylaxis of malaria that the subjects that follow are here 
discussed. 
In any thorough campaign against the malaria fevers the dis¬ 
covery and treatment of latent infections, the treatment of gamete 
carriers, or carriers of malaria, and the proper treatment of initial 
and recurrent cases of the disease are fully as important as other 
methods of prophylaxis, and yet, until recently, these subjects have 
been looked upon as being practically outside the province of the 
sanitarian and of preventive medicine. As a matter of fact, the 
prevention of “ carriers ** of any infection and the treatment of 
those who have become carriers is one of the most important func¬ 
tion of preventive medicine, while the discovery of latent infec¬ 
tions and their treatment would logically appear to be the first step 
in the prevention of any disease. This has been found to be true 
in typhoid fever, diphtheria, entamoebic dysentery, cholera, and 
other infectious diseases and it is equally true in the malarial in¬ 
fections. 
The discovery and treatment of latent infections .—By a latent 
malarial infection we understand one in which the plasmodia may be 
demonstrated in the peripheral blood, but in which no clinical symp¬ 
toms of sufficient gravity to attract attention are observed. The 
term includes both those instances in which no definite symptoms of 
malaria have ever been observed, and those cases in which the disease 
is latent between recurrences. 
It is well known that in malarial localities a considerable propor¬ 
tion of individuals in apparently fair health are “ carriers ” of the 
plasmodia, and that the natives of these regions possess an acquired 
immunity to the usual effects of the malaria toxin, although the 
plasmodia may develop in such individuals and be demonstrable in 
the blood. It has also been shown that insufficient treatment of 
