MALARIA: THE PESTILENCE THAT WALKETH IN DARKNESS; THE GREATEST FOE OF
THE PIONEER
Malaria has probably killed more human beings than all the wars that
have ever devastated the globe. Some day the epic of medicine will be
written, and will show what a large and unexpected part it has played in
the progress of civilization. Valuable and essential to that progress as
were the classic great discoveries of fire, ships, wheeled carriages,
steam, gunpowder, and electricity, they are almost paralleled by the
victories of sanitary science and medicine in the cure and prevention of
that greatest disrupter of the social organism--disease. No sooner does
the primitive human hive reach that degree of density which is the one
indispensable condition of civilization, than it is apt to breed a
pestilence which will decimate and even scatter it. Smallpox, cholera,
and bubonic plague have blazed up at intervals in the centres of
greatest congestion, to scourge and shatter the civilization that has
bred them. No civilization could long make headway while it incurred the
dangers from its own dirtiness; and to-day the most massive and imposing
remains of past and gone empires are their aqueducts, their sewers, and
their public baths. What chance has a community of building up a steady
and efficient working force, or even an army large enough for adequate
defense, when it has a constant death-rate of ten per cent per annum,
and an ever recurrent one of twenty to thirty per cent, by the sweep of
some pestilence? The bubonic plague alone is estimated to have slain
thirty millions of people within two centuries in Mediæval Europe, and
to have turned whole provinces into little better than deserts.
In malaria, however, we have a disease enemy of somewhat different class
and habits. While other great infections attack man usually where he is
strongest and most numerous, malaria, on the contrary, lies in wait for
him where he is weakest and most scattered, upon the frontiers of
civilization and the borders of the wilderness. It is only of late years
that we have begun to realize what a deadly and persistent enemy of the
frontiersman and pioneer it is. We used to hear much of climate as an
obstacle to civilization and barrier to settlement. Now, for climate we
read "malaria." Whether on the prairies or even the tundras of the
North, or by the jungles and swamps of the Equator, the _thing that
killed_ was eight times out of ten the winged messenger of death with
his burden of malaria-infection. The "chills and fever," "fevernager,"
"mylary," that chattered the teeth and racked the joints of the pioneer,
from Michigan to Mississippi, was one and the same plague with the
deadly "jungle fever," "African fever," "black fever" of the tropics,
from Panama to Singapore. Hardly a generation ago, along the advancing
front of civilization in the Middle West, the whole life of the
community was colored with a malarial tinge and the taste of quinine
was as familiar as that of sugar. To this day, over something like
three-quarters of the area of these United States, the South, Middle
West, and Far West, if you feel headachy and bilious and "run down," you
sum it all up by saying that you are feeling "malarious." Dwellers upon
the rich bottom-lands expected to shake every spring and fall with
almost the same regularity as they put on and shed their winter
clothing. Readers of Frank Stockton will remember the gales of merriment
excited by his quaint touch of the incongruous in making the prospective
bridegroom of the immortal Pomona change the date of their wedding day
from Tuesday to Monday, because, on figuring the matter out, he had
discovered that Tuesday was his "chill-day."
Though the sufferer from ague seldom received very much sympathy at the
time, but was considered a fair butt for genial ridicule and chaff, yet
even there the trouble had its serious side. Through all those
communities there stalked a well-known and dreaded spectre, the
so-called "congestive chill," what is now known in technical language as
the pernicious malarial paroxysm. These were like the three warnings of
death in the old parable. You would probably survive the first and might
never have another; but if you had your second, it was considered
equivalent to a notice to quit the country promptly and without counting
the cost. In my boyhood days in the Middle West, I can recall hearing
old pioneers tell of little groups of one or more families moving out on
to some particularly rich and virgin bottom-land and losing two or
three or more members out of each family by congestive chills within
the first year, and in some cases being driven in from the outpost and
back to civilization by the fearful death-loss.
A pall of dread hangs over the whole west coast of Africa. The factories
and trading-posts are haunted by the ghosts of former agents and
explorers who have died there. Some years ago one German company had the
sinister record that of its hundreds of agents sent out to the Gold
Coast under a three years' contract, not one had fulfilled the term! All
had either died, or been invalided and returned home. It was malaria
more than any other five influences combined that thwarted the French in
their attempt to dig the Panama Canal and that made the Panama Railroad
bear the ghastly stigma of having built its forty miles of track with a
human body for every tie.
Malaria ever has been, and is yet, the great barrier against the
invasion of the tropics by the white races; nor has its injurious
influence been confined to the deaths that it causes, for these gaps in
the fighting line might be filled by fresh levies drawn from the
wholesome North. Its fearfully depressing and degenerating effects upon
even those who recover from its attacks have been still more injurious.
It has been held by careful students of tropical disease and conditions
that no small part of that singular apathy and indifference which steal
over the mind and body of the white colonist in the tropics, numbing
even his moral sense, and alternating with furious outbursts of what the
French have termed "tropical wrath," characterized by unnatural cruelty
and abnormal disregard for the rights of others, is the deadly work
of malaria. It is the most powerful cause, not merely of the
extinction of the white colonist in the tropics, but of the peculiar
degeneracy--physical, mental, and moral--which is apt to steal over even
the survivors who succeed in retaining a foothold. Two particularly
ingenious investigators have even advanced the theory that the
importation of malaria into the islands of Greece and the Italian
peninsula by soldiers returning from African and Southern Asiatic
conquests had much to do with accelerating, if not actually promoting,
the classic decay of both of these superb civilizations.
To come nearer home, there can be little question that the baneful,
persistent influence of malaria, together with the hookworm disease, has
had much to do both with the degeneracy of the Southern "cracker," or
"mean white," and with those wild outbursts of primitive ferocity in all
classes which take the form of White Cap raids and lynching mobs.
However this may be, the disease and the colonization habit brought in a
crude way their own remedy. The Spanish conquerors of Peru were told by
the natives that a certain bark which grew upon the slopes of the Andes
was a sovereign remedy for those terrible ague seizures. Indian remedies
did not stand as high in popular esteem as they do now; but they were in
desperate straits and jumped at the chance. To their delight, it proved
a positive specific, and a Spanish lady of rank, the Countess Chincona,
was so delighted with her own recovery that she carried back a package
of the precious Peruvian bark on her return to Europe, and endeavored to
introduce it. So furious was the opposition of the Church, however, to
this "pagan" remedy that she was completely defeated in her praiseworthy
attempt and was obliged to confine her ministrations to those who
belonged to her, the peasantry on her own estate. About half a century
later, the new remedy excited so much discussion by the numerous cures
that it effected, that it was considered worthy of a special council of
the Jesuits, who formally pronounced it suitable for the use of the
faithful, thereby attaching to it for many years the name of "Jesuit's
bark." Virtue, however, is sometimes rewarded in this world, and the
devoted and enlightened countess has, all unknown to herself, attained
immortality by attaching her name, Chincona, softened into _cinchona_,
and hardened into _quinine_, to the greatest therapeutic gift of the
gods to mankind. It is not too much to say that the modern colonization
of the tropics and subtropics by Northern races, which is one of the
greatest and most significant triumphs of our civilization, would have
been almost impossible without it. Its advance depended upon two
powders, one white and the other black,--quinine and gunpowder.
For nearly three centuries we rested content with the knowledge that in
quinine we had a remedy for malaria, which, if administered at the
proper time and in adequate doses, would break up and cure ninety per
cent of all cases. Just how it did it we were utterly in the dark, and
many were the speculations that were indulged in. It was not until
1880, that Laveran, a French army surgeon stationed in Algeria,
announced the discovery in the blood of malarial patients of an organism
which at first bore his name, the _Hematozoon-Laveran_, now known as the
_Plasmodium malariæ_. This organism, of all curious places, burrowed
into and found a home in the little red corpuscles of the blood. At
periods of forty-eight hours it ripened a crop of spores, and would
burst out of the corpuscles, scattering throughout the blood and the
tissues of the body, and producing the famous paroxysm. This accounted
for the most curious and well-marked feature of the disease, namely, its
intermittent character, chill and fever one day, and then a day of
comparative health, followed by another chill day and so on, as long as
the infection continued. One problem, however, was left open, and that
was why certain forms of the disease had their chills every fourth day
and so were called _quartan_ ague. This was quickly solved by the
discovery of another form of the organism, which ripened its spores in
three days instead of two. So the whole curious rhythm of the disease
was established by the rate of breeding or ripening of the spores of the
organism. Later still another form was discovered, which had no such
regular period of incubation and gave rise to the so-called irregular,
or _autumnal_, malarial fevers. That form of the fever which had a
paroxysm every day, the classic _quotidian_ ague, remained a puzzle for
a little longer, but was finally discovered to be due chiefly to the
presence of two broods, or infections, of the organism, which ripened
on alternate days and hence kept the entire time of the unfortunate
patient occupied.
The mystery of the remedial effect of quinine was also solved, as it was
found that, if administered at the time which centuries of experience
has shown us to be the most effective, between or shortly before the
paroxysms, it either prevented sporulation or killed the spores. So that
at one triumphant stroke the mystery of centuries was cleared up.
But here will challenge some twentieth-century _Gradgrind_: "This is all
very pretty from the point of view of abstract science, but what is the
practical value of it? The discovery of the plasmodium and its
peculiarities has merely shown us the how and the why of a fact that we
had known well and utilized for centuries, namely, that quinine will
cure malaria." Just listen to what follows. The story of the plasmodium
is one of the most beautiful illustrations of the fact that there is no
such thing as useless or unpractical knowledge. The only thing that
makes any knowledge unpractical is our more or less temporary ignorance
of how to apply it. The first question which instantly raised itself
was, "How did the plasmodium get into human blood?" The very
sickle-shape of the plasmodium turned itself into an interrogation mark.
The first clew that was given was the new and interesting one that this
organism was a new departure in the germ line in that it was an animal,
instead of a plant, like all the other hitherto known bacilli, bacteria,
and other disease-germs.
It may be remarked in passing that its discovery had another incidental
practical lesson of enormous value, and that was that it paved the way
for the identification of a whole class of animal parasites causing
infectious diseases, which already includes the organisms of Texas fever
in cattle, dourine in horses, the _tsetse_ fly disease, the dreaded
sleeping sickness, and finally such world-renowned plagues as syphilis
and perhaps smallpox.
Being an animal, the plasmodium naturally would not grow upon
culture-media like the vegetable bacilli and bacteria, and this very
fact had delayed its recognition, but raised at once the probability
that it must be conveyed into the human body by some other animal.
Obviously, the only animals that bite our human species with sufficient
frequency and regularity to act as transmitters of such a common disease
are those Ishmaelites of the animal world, the insects. As all the
evidence pointed toward malaria being contracted in the open air,
attested by its popular though unscientific name _mal-aria_, "bad air,"
and as of all forms of "bad air" the night air was incomparably the
worst, it must be some insect which flew and bit by night; which by
Sherlock Holmes's process promptly led the mosquito into the dock as the
suspected criminal. It wasn't long before he was, in the immortal
language of Mr. Devery, "caught with the goods on"; and in 1895 Dr.
Ronald Ross, of the Indian Medical Service, discovered and positively
identified the plasmodium undergoing a cycle of its development in the
body of the mosquito. He attempted to communicate the disease to birds
and animals by allowing infected mosquitoes to bite them, but was
unsuccessful. Two Italian investigators, Bignami and Grassi, saw that
the problem was one for human experiment and that nothing less would
solve it. Volunteers were called for and promptly offered themselves.
Their blood was carefully examined to make sure that they were not
suffering from any latent form of malaria. They then allowed themselves
to be bitten by infected mosquitoes, and within periods varying from six
to ten days, eight-tenths of them developed the disease. It may be some
consolation to our national pride to know that although the organism was
first identified in the mosquito by an Englishman and its transmission
to human beings in its bite by Italians, the first definite and
carefully worked-out statement of the relation of the mosquito to
malaria was made by an American, King of Washington, in 1882; though it
is only fair to say that suggestions of the possible connection between
mosquitoes and malaria had, so to speak, been in the air and been made
from scores of different sources, from the age of Augustus onward.
Another mystery was solved--and what a flood of light it did pour upon
our speculations as to the how and wherefore of the catching of malaria!
In some respects it curiously corroborated and increased our respect for
popular beliefs and impressions. While "bad air" had nothing to do with
causing the disease, except in so far as it was inhabited by songsters
of the _Anopheles_ genus, yet it was precisely the air of marshy places
which was most likely to be "bad" in this sense. So that, while in one
sense those local wiseacres, who would point out to you the pearly mists
of evening as they rose over low-lying meadows and bottom-lands, and
inform you that there before your very eyes was the "mylary just
a-risin' out of the ground," were ludicrously mistaken, in another their
practical conclusion was absolutely sound; for it is in just such air,
at such levels above the surface of the water, that the _Anopheles_ most
delights to disport himself. Furthermore, while all raw or misty air is
"bad," the night air is infinitely more so than that of the day, because
this is the time at which mosquitoes are chiefly abroad. In fact, there
can be little doubt that this is part of the foundation for that rabid
and unreasonable dread of the night air which we fresh-air crusaders
find the bitterest and most tenacious foe we have to fight. We have
literally discovered the Powers of Darkness in both visible and audible
form, and they have wings and bite, just like the vampire.
It was also a widespread belief in malarial regions that the hours when
you are most likely to "git mylary inter yer system" were those just
before and just after sundown; and now entomologists inform us that
these are precisely the hours at which the _Anopheles_ mosquito, the
only genus that carries malaria, flies abroad.
Of course, a number of popular causes, such as bad drainage, the
drinking of water from shallow surface wells, damp subsoils under the
houses, and especially that peculiarly widespread and firmly held
article of belief that new settlements, where large areas of prairie sod
were being freshly upturned by the plough, were peculiarly liable to
the attack and spread of malaria, had to go by the board,--with this
important reservation, however, that almost every one of these alleged
causes either implied or was pretty safe to be associated with pools or
swamps of stagnant water in the neighborhood, which would furnish
breeding-spots for the mosquitoes.
The discovery explains at once a score of hitherto puzzling facts as to
the distribution of malaria. Why, for instance, in all tropical or other
malarious countries, those who slept in second and third story bedrooms
were less likely to contract the disease, supposedly because "bad air
didn't rise to that height," is clearly seen to be due to the fact that
the mosquito seldom flies more than ten or twelve feet above the level
of the ground or marsh in which he breeds, except when swept by
prevailing winds. It also explained why in our Western and Southwestern
states the inhabitants of the houses situated on the south bank of a
river, though but a short distance back from the stream, would suffer
very slightly from malaria, while those living upon the north bank, half
a mile back, or even upon bluffs fifteen or twenty feet above the water
level, were simply plagued with it. The prevailing winds during the
summer are from the south and mosquitoes cannot fly a foot against the
wind, but will fly hundreds of yards, and even the best part of a mile,
with it. The well-known seasonal preference of the disease for warm
spring and summer months, and its prompt subsidence after a killing
frost, were seen simply to be due to the influence of the weather upon
the flight of mosquitoes. Shakespeare's favorite reference to "the sun
of March that breedeth agues" has been placed upon a solid entomological
basis by the discovery that, like his pious little brother insect, the
bee, the one converted and church-going member of a large criminal
family, the mosquito hies himself abroad on his affairs at the very
first gleam of spring sunshine, and will even reappear upon a warm,
sunny day in November or December. Perhaps even some of the popular
prejudice against "unseasonable weather" in winter may be traceable to
this fact.
Granted that mosquitoes do cause and are the only cause of malaria, what
are you going to do about it? At first sight any campaign against
malaria which involves the extermination of the mosquito would appear
about as hopeless as Mrs. Partington's attempt to sweep back the rising
Atlantic tide with her broom. But a little further investigation showed
that it is not only within the limits of possibility, but perfectly
feasible, to exterminate malaria absolutely from the mosquito end. In
the first place, it was quickly found that by a most merciful
squeamishness on the part of the plasmodium, it could live only in the
juices of one particular genus of mosquito, the _Anopheles_; and as
nowhere, not even in the most benighted regions of Jersey, has this
genus been found to form more than about four or five per cent of the
total mosquito population, this cuts down our problem to one-twentieth
of its apparent original dimensions at once. The ordinary mosquito of
commerce (known as _Culex_) is any number of different kinds of a
nuisance, but she does not carry malaria.
Here the trails of the extermination party fork, one of them taking the
perfectly obvious but rather troublesome direction of protecting houses
and particularly bedrooms with suitable screens and keeping the
inhabitants safely behind them from about an hour before sundown on. By
this simple method alone, parties of explorers, of campers, of
railroad-builders going through swamps, of the laborers on our Panama
Canal, have been enabled to live for weeks and months in the most
malarious regions with perfect impunity, so long as these precautions
were strictly observed. The first experiment of this sort was carried
out by Bignami upon a group of laborers in the famous, or rather
infamous, Roman Campagna, whose deadly malarial fevers have a classic
reputation, and has achieved its latest triumphs in the superb success
of Colonel Gorgas at Panama. While this procedure should never be
neglected, it is obvious that it involves a good deal of irksome
confinement and interferes with freedom of movement, and it will
probably be carried out completely only under military or official
discipline, or in tropical regions where the risks are so great that its
observance is literally a matter of life or death.
The other division of malaria-hunters pursued the trail of the
_Anopheles_ to her lair. There they discovered facts which give us
practically the whip-hand over malarial and other tropical fevers
whenever we choose to exercise it. It had long been known that the
breeding-place of mosquitoes was in water; that their eggs when
deposited in water floated upon the surface like tiny boats, usually
glued together into a raft; that they then turned into larvæ, of which
the well-known "wigglers" in the water-butt or the rain-barrel are
familiar examples; and that they finally hatched into the complete
insect and rose into the air.
Obviously, there were two points at which the destroyers might strike,
the egg and the larvæ. It was first found that, while the eggs required
no air for their development, the larvæ wiggled up to the surface and
inhaled it through curious little tubes developed for this purpose,
oddly enough from their tail-ends. If some kind of film could be spread
over the surface of the water, through which the larvæ could not obtain
air, they would suffocate. The well-known property of oil in "scumming
over" water was recalled, two or three stagnant pools were treated with
it, and to the delight of the experimenters, not a single larva was able
to develop under the circumstances. Here was insecticide number one. The
cheapest of oils, crude petroleum, if applied to the pool or marsh in
which mosquitoes breed, will almost completely exterminate them. Scores
of regions and areas to-day, which were once almost uninhabitable on
account of the plague of mosquitoes, are now nearly completely free from
these pests by this simple means. An ounce to each fifteen square feet
of water-surface is all that is required, though the oiling needs to be
repeated carefully several times during the season.
But what of the eggs? They require no air, and it was found impossible
to poison them without simply saturating the water with powerful
poisons; but an unexpected ally was at our hand. It was early noted that
mosquitoes would not breed freely in open rivers or in large ponds or
lakes, but why this should be the case was a puzzle. One day an
enthusiastic mosquito-student brought home a number of eggs of different
species, which he had collected from the neighboring marshes, and put
them into his laboratory aquarium for the sake of watching them develop
and identifying their species. The next morning, when he went to look at
them, they had totally disappeared. Thinking that perhaps the laboratory
cat had taken them, and overlooking a most contented twinkle in the
corner of the eyes of the minnows that inhabited the aquarium, he went
out and collected another series. This time the minnows were ready for
him, and before his astonished eyes promptly pounced on the raft of eggs
and swallowed them whole. Here was the answer at once: mosquitoes would
not develop freely where fish had free access; and this fact is our
second most important weapon in the crusade for their extermination. If
the pond be large enough, all that is necessary is simply to stock it
with any of the local fish, minnows, killies, perch, dace, bass,--and
presto! the mosquitoes practically disappear. If it be near some larger
lake or river containing fish, then a channel connecting the two, to
allow of its stocking, is all that is required.
On the Hackensack marshes to-day trenches are cut to let the water out
of the tidal pools; while in low-lying areas, which cannot be thus
drained, the central lowest spot is selected, a barrel is sunk at this
spot, and four or five "killie" fish are placed in it. Trenches are cut
converging into this barrel from the whole of the area to be drained,
and behold, no more mosquitoes can breed in that area, and, in the
language of the day, "get away with it."
Finally, most consoling of all, it was discovered that, while the
ordinary _Culex_ mosquito can breed, going through all the stages from
the egg to the complete insect, in about fourteen days, so that any
puddle which will remain wet for that length of time, or even such
exceedingly temporary collections of water as the rain caught in a
tomato-can, in an old rubber boot, in broken crockery, etc., will serve
her for a breeding-place, the _Anopheles_ on the other hand takes nearly
three months for the completion of her development. So that, while a
region might be simply swarming with ordinary mosquitoes, it would
frequently be found that the only places which fulfilled all the
requirements for breeding-homes for the _Anopheles_, that is, isolation
from running water or larger streams, absence of fish, and persistence
for at least three months continuously, would not exceed five or six to
the square mile. Drain, fill up, or kerosene these puddles,--for they
are often little more than that,--and you put a stop to the malarial
infection of that particular region. Incredible as it may seem, places
in such a hotbed of fevers as the west coast of Africa, which have been
thoroughly investigated, drained, and cleaned up by mosquito-brigades,
have actually been freed from further attacks of fever by draining and
filling not to exceed twenty or thirty of these breeding-pools.
In short, science is prepared to say to the community: "I have done my
part in the problem of malaria. It is for you to do the rest." There is
literally no neighborhood in the temperate zone, and exceedingly few in
the tropics, which cannot, by intelligent coöperation and a moderate
expense, be absolutely rid first of malaria, and second of all
mosquito-pests. It is only a question of intelligence, coöperation, and
money. The range of flight of the ordinary mosquito is seldom over two
or three hundred yards, save when blown by the wind, and more commonly
not more than as many feet, and thorough investigation of the ground
within the radius of a quarter of a mile of your house will practically
disclose all the danger you have to apprehend from mosquitoes. It is a
good thing to begin with your own back yard, including the water-butt,
any puddles or open cesspools or cisterns, and any ornamental water
gardens or lily-ponds. These latter should be stocked with fish or
slightly oiled occasionally. If there be any accumulations of water,
like rain-barrels or cisterns, which cannot be abolished, they should
either be kept closely covered or well screened with mosquito netting.
It might be remarked incidentally in passing, that the only really
dangerous sex in mosquitodom, as elsewhere, is the female. The male
mosquito, if he were taxed with transmitting malaria, would have a
chance to reëcho Adam's cowardly evasion in the Garden of Eden, "It was
the woman that thou gavest me." Both sexes of mosquitoes under ordinary
conditions are vegetable feeders, living upon the juices of plants. But
when the female has thrown upon her the tremendous task of ripening and
preparing her eggs for deposition, she requires a meal of blood--which
may be a comfort to our vegetarian friends, or it may not. Either she
requires a meal of blood to nerve her up to her criminal deed, or, when
she has some real work to do, she has to have some real food.
The mosquito-brigade have still another method of checking the spread of
malaria, at first sight almost a whimsical one,--no less than screening
the patient. The mosquito, of course, criminal as she is, does not hatch
the parasites _de novo_ in her own body, but simply sucks them up in a
meal of blood from some previous victim. Hence by careful screening of
every known case of malaria, mosquitoes are prevented from becoming
infected and transmitting the disease. Instead of the screens protecting
the victims from the mosquitoes, they protect the mosquitoes against the
victim.
This explains why hunters, trappers, and Indians may range a region for
years, without once suffering from malaria, while as soon as settlers
begin to come in in considerable numbers, it becomes highly malarious.
It had to be infected by the coming of a case of the disease.
The notorious prevalence of malaria on the frontier is due to the
introduction of the plasmodium into a region swarming with mosquitoes,
where there are few window-screens or two-story houses.
No known race has any real immunity against malaria. The negro and other
colored races, it is true, are far less susceptible; but this we now
know applies only to adults, as the studies of Koch in Africa showed
that a large percentage of negro children had the plasmodium in their
blood. No small percentage of them die of malaria, but those who recover
acquire a certain degree of immunity. Possibly they may be able to
acquire this immunity more easily and with less fatality than the white
race, but this is the extent of their superiority in this regard. The
negro races probably represent the survivors of primitive men, who were
too unenterprising to get away from the tropics, and have had to adjust
themselves as best they might.
The serious injury wrought in the body by malaria is a household word,
and a matter of painfully familiar experience. Scarcely an organ in the
body escapes damage, though this may not be discovered till long after
the "fever-and-ague" has been recovered from.
As the parasite breeds in the red cells of the blood, naturally its
first effect is to destroy huge numbers of these, producing the typical
malarial _anæmia_, or bloodlessness. Instead of 5,000,000 to the cubic
centimetre of blood the red cells may be reduced to 2,000,000 or even
1,500,000. The breaking down of these red cells throws their pigment or
coloring-matter afloat in the blood; and soaking through all the tissues
of the body, this turns a greenish-yellow and gives the well-known
sallow skin and yellowish whites of the eyes of swamp-dwellers and
"river-rats."
The broken-down scraps of the red blood-cells, together with the toxins
of the parasite, are carried to the liver and spleen to be burned up or
purified in such quantities that both become congested and diseased,
causing the familiar "biliousness," so characteristic of malaria.
The spleen often becomes so enormously enlarged that it can be readily
felt with the hand in the left side below the ribs, so that it is not
only relied upon as a sign of malaria in doubtful cases, but has even
received the popular name of the "ague-cake" in malarious districts.
So full is the blood of the parasites, that they may actually choke up
the tiny blood-vessels and capillaries in various organs, so as to block
the circulation and cause serious and even fatal congestions.
Obstructions of this sort may occur in the brain, the liver, the coats
of the stomach, or intestines, and the kidneys; and they are the chief
cause of the deadly "congestive chills," or pernicious malarial
paroxysms, which we have alluded to.
The kidneys are particularly liable to be attacked in this way; indeed,
one of their involvements is so serious and fatal in the tropics as to
have been given a separate name, "Blackwater fever," from the quantities
of broken-down blood which appear in and blacken the urine.
The vast majority of attacks of malaria are completely recovered from,
like any other infection, but it can easily be seen what an injurious
effect upon the system may be produced by successive attacks, keeping
the entire body saturated with the poison; while there is serious risk
of the parasite sooner or later finding some weak spot in the
body,--kidney, liver, nervous system,--where its incessant battering
works permanent damage.
How long the infection may lurk in the body is uncertain; certainly for
months, and possibly for years. Many cases are on record which had
typical chills and fever, with abundance of plasmodia in the blood,
years after leaving the tropics or other malarious districts; but there
is often the possibility of a recent re-infection.
Altogether, malaria is a remarkably bad citizen in any community, and
its stamping-out is well worth all it costs.