252 Arthropod Transmission of Disease 
Sendee summarize their conclusions in the statement, (i) that it is 
dependent on some yet undetermined fault in a diet in which the 
animal or leguminous protein component is disproportionately large 
and (2) that no pellagra develops in those who consume a mixed, 
well-balanced, and varied diet, such, for example, as that furnished 
by the Government to the enlisted men of the Army, Navy, and 
Marine Corps. 
Leprosy 
Leprosy is a specific, infectious disease due to Bacillus lepree, and 
characterized by the formation of tubercular nodules, ulcerations, 
and disturbances of sensation. In spite of the long time that the 
disease has been known and the dread with which it is regarded, 
little is known concerning the method of transfer of the causative 
organism or the means by which it gains access to the human body. 
It is known that the bacilli are to be found in the tubercles, the 
scurf of the skin, nasal secretions, the sputum and, in fact in prac¬ 
tically all the discharges of the leper. Under such conditions it is 
quite conceivable that they may be transferred in some instances 
from diseased to healthy individuals through the agency of insects 
and other arthropods. Many attempts have been made to demon¬ 
strate this method of spread of the disease, but with little success. 
Of the suggested insect carriers none seem to meet the conditions 
better than mosquitoes, and there are many suggestions in literature 
that these insects play an important role in the transmission of 
leprosy. The literature has been reviewed and important experi¬ 
mental evidence presented by Currie (1910). He found that mosqui¬ 
toes feeding, under natural conditions, upon cases of nodular leprosy 
so rarely, if ever, imbibe the lepra bacillus that they cannot be 
regarded as one of the ordinary means of transference of this bacillus 
from lepers to the skin of healthy persons. He believes that the 
reason that mosquitoes that have fed on lepers do not contain the 
lepra bacillus is that when these insects feed they insert their probos¬ 
cis directly into a blood vessel and thus obtain bacilli-free blood, 
unmixed with lymph. 
The same worker undertook to determine whether flies are able 
to transmit leprosy. He experimented with five species found in 
Honolulu, — Musca domestica, Sarcophaga pallinervis, Sarcophaga 
barbata, Volucella obesa and an undetermined species of Lucilia. 
The experiments with Musca domestica were the most detailed. 
