Report: Anti-Malarial Measures for Farm Houses and Plantations, by [Henry Rose Carter], [n.d.]

    Anti-Malarial Measures for Farm Houses and Plantations.

    Malaria is essentially a rural disease. It is found in towns
only as they approach rural conditions--i.e. in small towns and
in the suburbs of large cities--not in the bodies of large cities.
It is for this reason that the consideration of anti-malarial meas-
ures specially applicable for farm houses and plantations may be
of interest.

    As is known, the direct cause of malarial fever is the presence
af an animal parasite in the blood of the man developing it. This
parasite is, in nature, introduced into the blood (only) by n the
bite of a certain kind of mosquito, rendered infective by biting a
man himself infected with malarial parasites and only thus introduced.

    There are certain conditions necessary for infection. Let us
note them, as they will show us what to guard against. To become
infected with malarial fever it is necessary to

    (1) To be bitten by a certain kind of mosquito.

    Only mosquitoes of the genus Anophelina--and not all species
of that genus--are concerned in the conveyance of malaria. To guard
against all mosquitoes is no wiser than to defend one's chickens
from all birds because hawks do prey on them.

    ( 2 )

    (2) This mosquito to have been infected by previously biting
some man infected with the malarial parasite.

    It is not true, as one often hears, that mosquitoes of swamps
who have had no access to men can convey malaria. The early English
expeditions direct to America as to the Orinoco and Darien rarely
recorded fever among them until after meeting Spaniards. Those that
came by the Slave Coast of Africa suffered severely.

    (3) That some time, usually not less than eight to ten days,
must elapse between the infection of the mosquito and the biting
which infects the other man.

    This is the time for the completion of the sexual cycle of the
parasite, which occurs in the body of the mosquito, and for the
product of this union--the Sporozoites--to reach her salivary glands.
Until this--the extrinsic incubation of malaria--is accomplished
the mosquito is not infective.

    No description of this mosquito will be given except to say

    (1) That in the female, the sex that bites, the palpi--two
little projections on either side of the probocis--are nearly as

    (2) That when resting after a meal of blood the anapholes has
her fore legs, proboscis, body and hind legs all in one line, or
nearly so, usually at a considerable angle--45° to 90°--with the wall
while other mosquitoes are "humped up," both fore and hind legs being
bent on the body toward each other. It is a slight, graceful mosquito.

    Nor shall I go into its life history save only to say

    (1) That the female lays her eggs in the shade of grass or

    (2) That it is from 15 to 22 days, or longer, depending on
the temperature, from the time the egg is laid to the birth of the
adult mosquito.

    (3) That the forms between the egg and the mosquito-- larva
and pupa--live in water, but breathe air from the atmosphere and
must come to the surface every few minutes to get it.

    (4) That they are attracted by light for some distance and
are conveyed by light winds. How far they travel has not been deter-
mined. One species--the white footed anopheles in Panama was found
in large numbers nearly a mile from its breeding place. It was
found, however, in a village brilliantly lighted by electricity and
the conditions were otherwise favorable for conveyance. Generally

    (5) That she flies and feeds in the U. S. almost exclusively
in the evening and at night. The bite is little painful--one used to
the pestiferous day mosquito will not notice it--and the insect is
so shy that she rarely bites a moving--i.e. a waking-person-and
hence ana h [p] heles frequently exist where there are no complaints of
mosquitoes.

    (6) That she comes into the house at night, attracted by light
(and possibly smell) feeds and, if not exceedingly full, leaves it
as soon as it becomes light. If she can not she hides in some dark
place during the day, so that not finding anopheles in the day time
in a room with open windows is no proof that they were not present
at night.

    I lay some stress on (5) and (6) because I have known good men
puzzled to account for a malarial outbreak where they could find

    Since malaria is contracted only from the bite of a certain
kind of mosquito rendered infective by having fed on a man himself
infected with malaria, if we can keep, the infective insect from the
well man or the man harboring the malarial parasite in his blood
from infecting the insect there will be no spread of malaria. Either
method perfectly carried out would extinguish the disease. We will
consider the second method first.

    I

    Measures Involving the Control of the Human Host.

    The writer is on record as regarding methods to prevent the
access of mosquitoes to men infected with malaria as in practice
entirely inefficient for the elimination, or even control, of malaria
in villages or thickly settled communities where it is prevalent, as
in some parts of the tropics. The reason is the large number of
"carriers", people who carry malarial parasites in their blood and
are infective to mosquitoes with no signs of illness whatever. There

    But for families in farm houses and in plantation houses not
too close to colored quarters much may be done on this line. Espec-
ially is this true of places in districts not very malarious, or
at least, with a long period--winter and spring--during which mala-
ria is not contracted so that it is reasonable to expect during some
part of the year that none of the household are carriers.

    (a) In such cases, then, a case of malarial fever should be
treated--as it is--like a communicable disease. No access to anoph-
eles mosquitoes should be allowed. It should be kept in a screened
room and--not "or"--under a mosquito bar, especially at night.

    (b) For sanitary reasons quinine should be freely administered
and in sufficient doses, with such other medication as is necessary,
to cure the case, to rid him of his parasites--not simply to reduce
their number--and get him on his feet. Remember that a few--say two--
doses of quinine will practically free the blood vessels of the skin

    Visitors convalescent of malarial fever or from badly infected
neighborhoods are so apt to be carriers that the above anti-malarial
measures are indicated for them also as far as they can be applied.
Parasites in the blood of a carrier can always be demonstrated by
blood examination. Negative findings from Ross' thick film may be
regarded as conclusively negative.

    (c) Killing the mosquitoes which one finds in the sick room
each morning, with a fly-flap or small pan of coal oil (for the
ceiling) may be made an efficient anti-malarial measure. Anopheles
enter the room in the evening or night when the light burns, feeds
and remains quiet until morning; then, unless she can quickly get
out, and the windows are frequently shut toward morning, or if very
full of blood hides herself in dark corners, where she can be easily

    These measures are of little value in a community unless one
can be assured that it is free from carriers to start with. It is, I
think, of none in houses close to the quarters of negroes, as is fre-
quently the case in Southern plantations; so many negroes, espec-
ially children, are carriers.

    ( 10 )

    (d) The use of quinine by well people in small doses to pre-
vent the development of malaria is not admitted to be efficient
universally by sanitarians (and some observations by Medical Offi-
cers of the U. S. Navy wouls show that it is certainly not so
always). Yet the general consensus of opinion is in its favor and
comparative experiments by the Japanese in Formosa and the Germans
in East Africa would show it decidedly valuable. There are two
methods of giving it, one from three to five grains a day and one
a single dose of ten or even fifteen grains once per week. The
latter seems to give the best results--certainly in proportion to
the quinine taken. The former was mainly the method used on the
Canal Zone. It gave, I think, no discomfort to those using it, as
a great many of the higher officials and their families did for
long periods from '04 to '06 when malaria was prevalent. This method,
in the opinion of the writer, is mainly of use to tide over a
specially bad season. He is sure it prevents sickness; it may
prevent infection.

    (e) Personal hygiene, especially the avoidance of getting

    II

    Measures Involving the Control of the Insect Host.

    The measures found efficient for villages, etc., are, of course,
efficient for farm houses, but some--and these among the most ef
ficient in the former--are not practicable for farm houses on account
of the expense involved. Fortunately farm houses are usually better
situated with regard to elevation, wind and proximity to marshes
than are villages.

    It may be taken as a principle in bimomics that when an animal
is exceedingly prolific, like rats, mosquitoes, flies, etc., that
control of their numbers, far less their extermination, is not pos-
sible by killing the individuals. One must destroy their breeding
places, their shelters or their food supply. We attempt the first
with mosquitoes. These methods under this head are briefly

    (1) To prevent breeding of anopheles by destruction of their
breeding places. And in addition

    ( 12 )

    (2) To kill their larvae in such breeding places as we fail
to destroy.

    (3) To prevent the access to the men we would protect of such
anopheles as exist in spite of the above attempts to destroy them.

    Obviously any one of these methods perfectly carried out would
be sufficient. Each one is intended to supplement the imperfect
success of the others. But the problem is so difficult that imper-
fect success with any one--or may be with all--is the most that can
be hoped for on most farms and plantations in malarial regions.

    (1) To destroy the breeding places, then, one drains all pools,
marshes and wet lands near the house and cleans up the banks of the
streams.

    If this drainage be done by open ditches it is likely enough
that they will themselves breed anopheles, although in less-- gen-
erally far less--number than formerly. Tile or box or "blind" drain-
age generally is not open to this objection. If the pools and small
streams contain fish, cleaning up of their edges so that the fish
can get to the larvae will be sufficient.

    ( 13 )

    (2) Ponds which can not be drained are best treated by coal oil.
This forms a film on the surface through which the larvae can not
pass to get air and without air they die. It takes a very small
amount. The oiling in the U. S. Heeds to be done only about once
in two weeks, but it is safer to do so every week as one is less apt
to forget it. It is of little use in ponds of large surface or with
grass growing in them and, in general, is far less dependable than
drainage. [✗] Foot note [Foot note here]

    These last two measures, which are the sheet anchors in anti-
malarial work for communities, are less applicable for farms on
account of the expense. The area to be freed from breeding places,
however, is less--one-half to one-sixteenth less--for the area varies
as the square of the distance of flight. In estimating what area
is dangerous naturally the seasonal prevailing winds must be taken
into consideration as much as, or more than, the distance. [✗ Foot note here]

    (3) To prevent the access of anopheles to man there are three
things of service

    (a) To cut down the brush and tall weeds about the house.

     [✗] Foot note for page 17

    The use of agents which act by poisoning the larvae, as Pinotas
oil, is not taken up. There is a wide field for their use in village
and community sanitation, but the need of special material and methods
render them, it is thought, little applicable to purely rural work.

    ( 14 )

    These harbor mosquitoes--they do not breed them--and keep a supply
close to the house. Porch vines and mostbshrubbery also act in this
way. Anopheles can not live long in full sunlight. A treeless,
shrubless yard open to the sun and wind--shade being given by gal-
leries and awnings--is the most sanitary so far as malaria is con-
cerned, but one may pay a higher price in comfort and beauty than
the risk is worth. Trees, high branched, furnish little shelter to
mosquitoes unless very dense. Aromatic trees and shrubs are usually
avoided by them.

    (b) Planting a screen of trees some distance from the house
between the mosquito breeding place and the house. This probably
serves to hide the lights of the house from the marsh or stops the
mosquitoes brought by the breeze from it--or both.

    (c) Screening and mosquito bars. (a( and (b) are of some value,
but screening is our reliance to keep out mosquitoes. Properly ap-
plied it will do it. Screening is many fold better then mosquito
bars which seldom protect for long if anopheles be abundant. Screened
houses, however, are safe to intelligent and careful people, provided

    No. 16 mesh wire is the best for screens. A very few anopheles
may pass No. 14, but the mesh is large enought to be painted which
will double its time of lasting and hence halve its cost and after
one painting no more will pass. If one screens against stegomyia 66 [--]
two sizes smaller should be used. The writer has used the ordinary
bobinet of mosquito bars, some times single, sometimes double. It
is simply tacked over the m entire window opening on the outside. It
made a perfect screen and was cheap. It lasted one season.

    As few entrances are possible to the screened part of the house
should be allowed. It is nearly always possible to cut them down to
two. The screens in the windows should, if possible, be fixed so
that they can not be opened--especially in the servant's part of
the house. Unless they exclude mosquitoes, no matter how the window
is opened, i.e. cover the whole window, constant pains must be taken

    Screen doors must open outward and the light inside should be
arranged so as not to fall on the door when shut--else mosquitoes
will gather on it and come in when opened. It should, of course,
have a strong spring to close it. It is far better to screen
the porch if it runs around a good part of the house, than to screen
the doors and windows on that side. It is also more expensive. It
will do little good, however, to rely on a screened house and sit,
in the evening on an unscreened porch.

    When the door of entrance is at the top of a flight of steps,
no landing intervening, it should be so placed that the edge of the
door opposite the hinge comes as near the middle of the length of
the step as may be. This may be done

    (a) By ha b [v] ing folding doors, one best stay fastened.

    (b) By moving the whole door to the left and fill in the space
to the right by screening.

    The reason is that one always goes up about the middle of the

    Naturally all screens and screen doors must fit tightly and be
heavy enough not to warp. Where they do not fit tight and are im-
movable the writer has frequently rendered them mosquito proof by
caulking the openings with newspapers. An imperfectly screened house
is simply a mosquito trap. They come in at small crevices, at night,
which they find by the light streaming through and, at daylight, fly
directly to the screened windows through which they can not go and

    To sum up

    For farm houses anti-malarial measures based on the control
of both the human and the insect host should be used.

    Of the first the isolation of men sick of malarial fever from
mosquitoes is the most important.

    Of the second, draining mosquito breeding land near the house,
especially to windward, is of great value.

    Of almost equal value is the screening of the house. This is
always possible. Drainage, unfortunately, is not inmmany parts of
the country. Until drainage is done screening must be our anchor
anchor in preventing malarial fever in farm houses.

    The problem of drainage should be taken up both by the indi-
vidual farmer and by the community just as plantation and county
roads are.