IS MOSQUITO OR MAN THE WINTER CARRIER OF 
MALARIA ORGANISMS? 
By M. Bbuin Mitzmain, Technical Assistant, United States Public Health 
Service. 
The potential hosts, mosquito and man, were studied to determine 
the carrier responsible for the perpetuation of the malaria organ¬ 
ism during the inactive period of winter. An effort was made to 
show where the causative agent of malaria remains latent in locali¬ 
ties having a dormant season, during which the anopheline mosquitoes 
hibernate. The results of this study are given herewith. The solu¬ 
tion of the problem is aimed at because its economic importance 
appears to be not inconsiderable, judging from the discussion devoted 
to it by many writers on malaria epidemiology. 
LITERATURE. 
The available references in the literature on this problem of hiber¬ 
nation are as follows: 
Herms (1915) has given probably the best exposition of the relationship of 
man and mosquito in regard to the question, “ How does the malaria parasite 
overwinter?” He is quoted as follows: 
“ Since malaria has a typical seasonal occurrence, with little or no appear¬ 
ance during the winter months, the question arises, Does the parasite over¬ 
winter in its human host to break out in the spring in individual cases by the 
process of parthenogenesis, or does it overwinter in the body of the mosquito? 
The weight of evidence is against the latter possibility. The writer believes 
that the Anopheles mosquito seldom or ever takes a suck of blood before going 
into hibernation. A suck of blood would militate against the life of the mos¬ 
quito inasmuch as it causes the development and ultimate extrusion of ova 
and that terminates the life of the insect. Other physiological reasons, involv¬ 
ing further increased metabolism, seem to discount the possibility of success¬ 
ful hibernation. Furthermore, the writer has seen great numbers of voracious 
Anopheles in the spring both indoors and out, and has been frequently bitten 
by these as have many others without becoming infected. These hibernated 
individuals on coming out early in the spring bite viciously even at noonday. 
Furthermore, evidence that infected mosquitoes exist during the winter months 
seems to be lacking or has been overlooked. 
“ On the other hand, latent human infection has been amply proved, and 
this may easily lead to the infection of the mosquitoes appearing in the early 
spring and thus lead to the spread of malaria as the- season advances.” 
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