C. G. Hewitt 
173 
Mode of infection. 
The larvae of the flies belonging to the genus Fannia inhabit, as 
will be seen from the preceding account of their breeding habits, 
excrement and decaying vegetable products; and the female flies, 
guided by their sense of smell and impelled by their maternal instincts, 
seek such substances. They are attracted to excrement, decaying, 
putrefying or purulent s>ibstances. These facts render several methods 
of infection po.ssible. 
In the case of intestinal myiasis, the flies may have deposited their 
eggs in or upon rotting or decaying fruit, vegetables or other food 
which may be eaten in a raw state, and thus the eggs or young larvae 
will be taken into the digestive tract. Or, the flies, which are generally 
to be found depositing their eggs in the old-style privies, may deposit 
their eggs in or near the anus, especially if the person is somewhat 
costive. The larvae, on hatching, make their way into the rectum and 
thence into the intestine. This latter mode of infection is probably the 
common one in the case of infants belonging to careless mothers. Such 
infants are sometimes left about in an exposed and not very clean 
condition, in consequence of which flies are readily attracted to them 
and deposit their eggs. 
The infection of the urinary tract is more difficult to understand. 
The flies are no doubt attracted to the genital apertures by the 
different albuminous secretions, spermatic, menstrual, gonorrhoeal or 
leucorrhoeal. The larvae would feed upon the muco-purulent secretions. 
It is easier to understand the infection of the urinary tract of a woman 
rather than that of a man. The case recorded by Chevril indicates 
fairly clearly how the female urinary tract may be infected by the 
continued or prolonged exposure of the organ. As the flies are 
frequently found in bedrooms the infection of both sexes during hot 
weather is sometimes rendered possible. 
The whole subject of the relation of these flies to myiasis of the 
intestinal and urinary tracts is one which has received comparatively 
little atteirtion. Certainly not the attention it deserves on account of 
the complications incident to such infections that may arise. 
