Vol. 60, 1909 - University of North Carolina at Chapel Hill

S4
THE CHARLOTTE MEDICAL JOURNAL
of flagella, found in the salivan' glands. Frost is invariably fatal to its life. It cau- I
Thus when such an infected mosquito bites not stand drought, but the dry season in |
another individual the lubricating fluid or the countries where the mosquito seems to .
secretion of its puncturing apparatus will abound is never so much prolonged as to i
carry the parasites into the blood and trans- completely dry up the usual breeding places. !
mit the disease. Only the female anopheles Under suitable conditions it is a long-lived \
!
bite; hence, they alone ran be responsible insect: a specimen has been known to live i
for spreading the infection. They fly mostly for 75 days after hatching in the laboratory.
'
at night or in the dusk of the evening, while It has been definitely shown that a period
the common mosquito or at/tw, which can- of at least 12 days, at a temperature of 80
not carry malaria, flies often in the day to 85° P., was necessary before the infected
j
j
i
time; and there are other physical differ- insect could transmit the disease; but a ',
ences between them, which have been thoroughly
studied.
mosquito which had reached the age of 70
days was able to produce a case of yellow I
j
i
:
I
!
The importance of the studies regarding fever 57 days after it became infected. The
malaria cannot be overestimated. Among stegomyia bites principally in the late afterother
hitherto obscure problems, they have noon, though it may be incited to take blood i
explained the relation of the disease to at any time of the day. The insects are
marshy districts, the seasonal incidence, abundant from March to September, and
the nocturnal infection, etc. More import- have been captured even in November.
ant still, these studies have pointed out They are generally believed to be incapable
clearly the way by which malaria may be of long flights unless materially assisted by
'
i
prevented: I'irst, the recognition that any the wind. Their tendency, at any rate,
j
individual with malaria is a source of dan- seems to be to remain restricted within very j
ger in a community, so that he must be limited areas, unless carried afar by other •
thoroughly
the importance
treated
of the
with quinine; second,
draining of marshy
means
observed
than
that
natural
not all
flight.
stegomyia
It
mosquitoes
has been |
;
i
j
districts and ponds in which mosquitoes
breed; and third, that even in the most infected
regions persons may escape the diswhich
bite a yellow fever patient become
infected, but that of several which bite at
the same time some may fail either to get
i
!
ease by living in houses thoroughly pro- the parasite or to allow its later developtected
from mosquitoes by nets in windows ment in the body. How long do infected
and doors. mosquitoes remain dangerous to the non-
Yellozc Fever.—The results of the recent immune community? This is a question
experiments of Reed, Carroll and Agra- that cannot be positively answered at presmonte
make it certain that yellow fever is ent, but there is good presumptive evidence
i
|
(
I
•
transmitted by the bite of a mosquito, that the insects may harbor infection through
stegomyia faciata, in the same way that the winter, under favorable conditions, and
i
<
malaria is transmitted by the anopheles, be ready to transmit it in the spring, or that I
although the specific organism causing yel- once infected they can transmit the disease \
low fever has not yet been discovered. at any time during the balance of their i
'
The following interesting facts are known lives.
regarding the stegomyia: It is spread over The brilliant practical results obtained in t
a wide range of territory, embracing many the prevention of yellow fever, since these .'.
varieties of climate and natural conditions, investigations regarding the cause of the i
It has been found as far North as Charles- disease have been made, which have been
ton, S. C, and as far South as Rio de la demonstrated by the work of the U. S. i
Plata. There is no reason to believe, there- Marine Hospital Service in Havana, New \
fore, that it may not be present at some Orleans and Panama, render it certain that i
time or other in any of the intermediate yellow fever will never again become prevalatitudes.
Brackish water is unsuited for lent in this country. In cities where all .:
the development of the larvae. The stego- infected persons are immediately quaran- ]
myia seems to select any deposit of water tined and efficiently isolated by protective ^
which is comparatively clean. Defect- netting, and all breeding places of the spe- >
ive drains along the eaves of house-roofs, cific mosquito are drained or properly pro- i
open cisterns, and the like, are favortei tected by screening (as open cistern, etc.)
breeding places; indoors they find an excel- from the deposit of larvae, there is no doubt ,
lent medium in the standing water of cups that the disease can be controlled,
and other vessels. Like other ctiHcidae, to Rabies.—Until recently all of the numer- :
'
which family it belongs, it prefers to lay at
night. It is eminently a town insect, seldom
breeding far outside of the city limits,
which explains the well-founded opinion
ous researches regarding the cause of hydrophobia
have given negative results. The
latest studies, however, make it probable
that this disease may be added to the list of
that yellow fever is a domiciliary infection, infectious specifically caused by protozoa.
'