_PARASITICAL DISEASES (MALARIA, YELLOW FEVER, HOOKWORM, BUBONIC PLAGUE,
AND PELLAGRA)_
_Malaria._
From time immemorial, malaria (or fever-and-ague) has been one of the
great plagues of humanity. No advance outpost of civilization but has
suffered, more or less severely, from this disease. Dickens, in one of
his novels, describes graphically the disease as it existed in the early
American settlements, and vividly portrays its ravages, both mental and
physical, among the pioneer settlers. Certain sections of the world have
been especially noted for the prevalence of this disease, making
extensive regions practically uninhabitable. The vicinity of Rome, with
its swampy marshes and low-lying areas, has been one of these plague
spots. The jungles and swamps of the equator and the coastline of Africa
and South America and the valley lands of the Mississippi River have all
been noted as most dangerous districts for human beings to live in. Even
in civilized communities the ravages of the disease have, under
conditions most conducive to malaria, been fearful, so that only most
urgent requirements of mining, manufacturing, or similar material
processes have prevented the obliteration of entire communities.
The cause of the heavy death roll resulting from a bold defiance of the
reputation of these localities--a defiance bravely adopted by hardy
pioneers, by agents of trading companies, and by representatives of
governments--has been, up to the last ten years, assigned to the
water-laden condition of low-lying ground. Swamps and stagnant pools,
moisture-laden air, and a hot climate have been universally considered
to be the cause of the fever, and the transmission of the disease has
been supposed to be due to the passage through the moist air of the
germs of the disease, although the exact form and behavior of these
germs was unknown. Certain specifics have been proved by experience to
have some value. For instance, it has been found that planting a row of
trees between the house and a pool from which malaria might come has
been of aid in warding off the disease. In a number of cases a thick row
of eucalyptus trees, so associated in the popular mind with this purpose
that they are known as the malaria tree, have been planted as a tight
hedge with apparently very useful results. Drainage or filling up the
low lands has always been found to reduce the prevalence of the disease.
Many years ago the use of quinine in large doses was found to be a
specific, and the writer well remembers, on the occasion of his visit to
a malarial region, buying quinine at the grocery store by the ounce in
the same way that one would buy spices or tea, the dose being a
teaspoonful. Why quinine should prevent the daily or periodical chills
characteristic of the disease was not known, or why a row of eucalyptus
trees interfered with the development of the disease was not known, and
people generally were content to rest with the knowledge of these facts
only.
_Mosquitoes and malaria._
[Illustration: FIG. 78.--Resting positions for ordinary mosquito (left)
and malarial mosquito (right).]
In the year 1900, however, English scientists, working in the Roman
Campagna, demonstrated conclusively that which had been vaguely
suggested before, namely, that the cause of malaria is a parasite
composed of little more than an unformed mass of protoplasm, not
floating in the air at all, but transmitted only by the bite of a
mosquito. By a series of most interesting experiments, conducted by them
and by other scientists in other parts of the world, it has been
definitely proved that when a mosquito bites an individual suffering
from malaria, the mosquito draws up into his body, along with the blood
of the bitten person, some of the malarial parasites. In the body of the
mosquito, the parasite develops, requiring for a full-grown specimen
about seven days; then, if the mosquito bites another person, the
parasite is injected into the skin of the victim, and in the course of
about a week a good case of malaria ensues.
Fortunately, only a small proportion of the number of mosquitoes in the
world are capable of nourishing the malaria parasite. Under ordinary
conditions about 5 per cent of all mosquitoes found are malarial, and a
particular name has been given to those capable of transmitting the
disease. The ordinary mosquito is known as the "culex," while the
malarial kind is known as "anopheles." Figure 78 shows the
characteristic attitude of the two kinds by which the one can be
distinguished from the other when resting on a wall or ceiling. As will
be noticed in the drawing, the culex carries his body parallel to the
wall with his hind legs crossed over his back. The harmful mosquito, the
female anopheles, always hangs on by her front legs and has her body at
an angle of about forty-five degrees to the surface to which she clings,
her hind legs hanging down. The wings of the harmless mosquito are
usually mottled, while the wings of the malarial mosquito are of an even
color. The details of the behavior of the parasite on its long journey
from the original malarial patient through the body of the mosquito and
into the body of the person bitten is full of interest to the scientist,
who must, however, be provided with a good microscope to follow such
minute bodies; but the methods of avoiding the disease are more
pertinent to our present purpose.
While quinine is still recognized as the particular antidote for the
malarial poison, efficient as we know now because it is poisonous to the
parasite and not because it has any particular effect on the person, of
late years more and more stress is being laid on the elimination of the
mosquito. Naturally, if the mosquito can be destroyed and the
transmission of the disease thus prevented, there will be no further
need of quinine. The general impression that swampy land is favorable
to the development of malaria is correct, but not because the damp air
is itself pernicious. The significance of the damp ground lies solely in
the fact that mosquitoes in one stage of their existence require water
for their development. They breed only in water and always deposit their
eggs in water, on the surface of which the eggs float in very small
layers. The eggs hatch into larvae or wrigglers, which also must remain
in water for development, and it is not until the third stage, that of
the full-grown mosquito, that the animal leaves the water which was his
birthplace. Obviously, therefore, if there is no water there can be no
mosquitoes.
_Elimination of mosquitoes._
Another pertinent fact discovered by scientific research is that the
development of the malarial mosquito is confined to the vicinity of
stagnant pools, because in fresh water, where fish are to be found, the
eggs and larvae of the mosquito are a most acceptable fish food. One of
the most practical ways, therefore, of getting rid of possible
mosquitoes is to make sure that the pond always contains a number of
fish. Woods Hutchinson gives the following interesting description of
the way this fact was discovered:--
"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 an 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."
[Illustration: FIG. 79.--Top view is of larva of Anopheles. Bottom view
is of larva of Culex.]
Another factor in the development of the mosquito from the egg to
full-grown mosquitohood is that in the larvae stage air must be supplied,
curiously enough, through the tail which projects slightly above the
surface of the water as the larvae hang head downwards (see Fig. 79). If
the surface of the water is covered with some impervious material, the
mosquito larvae will be suffocated, and it has been found that oil lends
itself most readily to this desirable purpose, applied at the rate of
one ounce per fifteen square feet of water surface. The oil spreads out
over the surface in a very thin film, but persistent enough to keep off
the air supply from the mosquito larvae. This method, about which much
has been written and said, is perhaps the one most commonly employed,
and its results have been most satisfactory. In the vicinity of the city
of Newark, New Jersey, for instance, is an area of about 3500 acres, 8
miles long and about 3 miles wide, practically all marshland. In 1903
ditches were dug throughout this marsh in such a way that the surface
water was drained off, drying the ground so that hay can now be cut
where formerly rubber boots were necessary to get onto the ground at
all. The consequence has been that the mosquitoes have practically
disappeared from this region, formerly frightfully infested, and the
cost of the 70 miles of small ditches dug has been amply repaid by the
freedom from malaria as well as from the nuisance of the ordinary
mosquito.
Other campaigns have been waged, using kerosene or crude petroleum for
the coating of ponds or pools. Wherever clear water exists the kerosene
treatment is probably best. Where marshland is found, through which the
kerosene penetrates with difficulty, drainage is a more useful method.
The size of the pools required for the development of the mosquito is
very small. Thousands of mosquitoes may be formed in the amount of water
contained in an old tomato can, and barrels half full of rain water or
pools of water in the vicinity of an old pump or in the barnyard will
afford golden opportunities for mosquitoes looking for a place to lay
their eggs. While the ordinary culex requires from one to two weeks only
for the complete transition from egg to mosquito, so that a pool filled
with rain water and not dried up within that period will be sufficient
to develop a brood, the malarial mosquito requires much longer--two or
three months--for the full completion of her development. It is,
therefore, a simple problem for an individual householder to search out
the pools which remain filled with water for a period of two months, and
either stock them with fish, drain them entirely, or coat them with
kerosene. No hesitation need be felt about the result of this treatment.
It will positively eliminate all malaria in the vicinity if the work is
thoroughly done.
_Limitation of mosquito infection._
The distance that the malarial mosquito can fly is of interest as
indicating the distance which one must go from a house, hunting for
available pools. All mosquitoes are unable to fly against the wind, so
that, as already noted, one side of a swamp may be comparatively free
from malaria, while the other side may be overrun with it, merely on
account of the direction of the prevailing winds. Some mosquitoes that
breed in salt marshes may be carried for miles, so that a land breeze
will bring millions of the pests to seashore cottages which, with a sea
breeze, are quite free from them. The anopheles has a habit of clinging
to weeds, shrubs, and bushes when the wind blows, so that it is seldom
carried more than about two hundred yards from the place where it is
hatched. If all pools of water, therefore, within this radius are
disposed of, the elimination of malaria will logically follow.
If one is obliged to be in a region where malaria is common, the disease
can be avoided absolutely by protecting one's self from mosquitoes, and
since the anopheles prefer the early morning and evening hours, it is at
those times of the day particularly when precautions must be taken. It
was once thought that the night air caused malaria, and this had some
foundation in fact, because it is in the early evening that the
anopheles is on the wing. By staying in the house after sundown and by
carefully screening the doors and windows, one may live in a malarial
country with perfect immunity. Volunteers have lived for months in the
worst malarial regions in the world without a trace of the disease, the
only precaution being to keep the doors and windows screened and to
prevent mosquitoes from biting.
An interesting experiment was made some years ago by sending a malarial
mosquito by mail from Italy to England, where an enthusiast allowed
himself to be bitten by the insect. He had had no trace of malaria
before, but a week after the mosquito's bite he came down with the
disease. It has also been noted that in such parts of the country as
Greenland and Alaska, where mosquitoes are as thick as in the far-famed
New Jersey marshes, malaria does not result from the mosquito bites
unless a malaria patient from other countries starts the infection.
The disease itself may be mild or severe. It takes about a week after
the mosquito bites before the symptoms appear, and sometimes the attack
is postponed for weeks or months. Chills are the usual accompaniment of
the disease; in children under six, convulsions are more common. The
chill lasts from a few minutes to an hour, and directly after the chill
comes the fever, which lasts three or four hours. The attacks usually
occur every other day and sometimes every two days, generally at the
same time of day. When persons have lived for a long time in malarial
regions, the intermittency of the chill and fever is less noticeable and
the continuous character of the fever often leads the disease to be
mistaken for typhoid. The intermittent regularity of the fever, however,
although between attacks the temperature never falls to normal,
distinguishes this type of malarial fever from true typhoid. The
positive determination of the disease is possible by an examination of
the patient's blood, in which the malarial parasite can readily be
found. Quinine is the remedy and the only remedy, and, fortunately, it
does no harm, even before the character of the disease is positively
known. The chill seems to be due to the development of a new brood of
parasites in the blood of the malarial patient, and in order that the
quinine shall have its effect on the blood, it must be swallowed three
or four hours before the time of the expected chill, and then it will
probably prevent, not the next chill but the one after. If the quinine
cannot be taken directly with reference to an expected chill, then it
must be taken regularly, sometimes for months before the chills cease.
_Yellow fever._
Yellow fever, although not common in this country, is interesting as
being almost exactly similar in its mode of infection to malaria. It is
transmitted through a parasite, as is malaria, and can only be passed
along through the agency of another kind of mosquito, known as
stegomyia. In 1899 there was a serious outbreak of this pestilence in
the cities of our southern coast, and the terrors of the plague of the
Middle Ages were revived for a number of months. Trains going out of the
infected regions were stopped by crowds armed with guns and the
passengers prevented from proceeding, lest the disease might spread. No
goods or freight were allowed to pass out from the infected area, and
the prejudice against intercourse with the outside world went so far
that guards even forbade the carrying of disinfectants to the victims.
Like malaria, the disease is one requiring a hot climate, generally
because it is favorable to mosquito growth. It is most common in the
seacoast cities of the South, and is probably transmitted often by
mosquitoes brought on board ship. Since Havana has been cleaned up by
Americans, the danger formerly existing from intercourse with that city
has ceased, although only three years ago the writer stopped in a hotel
at Havana, where two persons had died of yellow fever a week before. The
smell of disinfectants in the hotel was so great that not a fly or
insect of any sort was visible, and no other hotel in the city could
have been safer or more comfortable. It has been proved positively that
yellow fever cannot be transmitted by direct contact, since, in the
interests of science, volunteers have slept in beds from which the dead
from yellow fever had just been removed without contracting the disease.
That the infection is due only to mosquitoes is proved by the fact that
later, when bitten by mosquitoes, they succumbed to the disease. It
requires about two weeks for the disease to pass through its regular
stages in the body of the mosquito, so that there is no possibility of
its transmission for that time after the mosquito has come in contact
with a yellow fever patient.
The symptoms of yellow fever are characteristic and very severe. The
eyes first become bloodshot and, in the course of two days, yellow,
whence the name of the disease. Severe vomiting is also characteristic,
the discharge being sometimes discolored like coffee or even tar and
known as black vomit. The skin appears yellow, a condition which lasts
for some time and is particularly noticeable if by the pressure of the
finger on the skin the blood is made to recede. Among persons previously
in good health, the death-rate is about that of typhoid fever, but among
those in unfavorable surroundings and among those given to the use of
alcohol, the rate will be much higher. Practically, it may be expected
that this disease, like malaria, will disappear from the face of the
earth. When the only requirement is the destruction of the mosquitoes
and when mosquitoes can be so easily killed as already explained, it is
only a question of time before mosquitoes and the diseases they cause
will be stamped out. In Havana, before 1901, the number of the deaths
yearly was about 750. In the year after the American intervention, when
Colonel Gorgas, by military command, insisted on the thorough cleaning
of the houses and the general use of kerosene in all drains and
cesspools, there was not one single death.
_Hookworm disease._
The third parasitical disease common in some parts of the United States
has received much attention during this last year and is known as the
hookworm disease. It is a new discovery in medical science, and whereas
the physical condition of the victim is usually a clear indication of
the disease, a positive diagnosis is always obtained by the use of the
microscope. Several years ago it was announced in the United States that
the laziness and shiftlessness of the poor whites living in the sand
lands and pine barrens of the South was due, not to any inherent
cussedness but to the presence of a parasite in the intestine, known in
Italy and Germany as the hookworm, the disease being called
Uncinariasis.
The development of the disease is interesting. The worm, which is about
an inch long and looks not unlike a bit of thread, lays eggs by the
thousand in the intestinal tract of a human victim. Afterwards they pass
out in the excreta and, favored by heat and moisture, develop in the
soil in about three days into minute larvae. These larvae have a most
extraordinary power of attaching themselves to and penetrating into the
human skin and body. They may also enter the human body in a drink of
water or on unwashed vegetables. In infected regions the soil becomes
fairly alive with these larvae, and it is hardly possible for a child to
walk barefoot outdoors without becoming infected. When the larvae have
penetrated the hand or foot, they begin a long and circuitous journey
through the body, moving from the extremities through the veins to the
heart and thence to the lungs. From here they are carried through air
cells into the bronchial tubes, thence along the mucous membrane up the
windpipe and down into the stomach and finally, from the stomach, they
pass out into the intestines, the goal of their long journey.
This all takes time, and probably from the time they enter the skin to
the time they begin their murderous work on the lining of the intestines
requires about two months. In the intestine the larvae develop into
adults; but before this final stage an intermediate existence is
reached, at which time they attach themselves to the mucous lining and
bore into it, presumably for the purpose of making a nest in which
later to lay their eggs. The burrowing parasite causes a great loss of
blood, and it is on account of the resulting anaemia that the poor whites
show always such incapacity, indifference, and apparent laziness. That
this disease is of importance in considering the hygienic condition of
the country is apparent when it is pointed out that in the southern part
of the United States, chiefly in the rural districts, there are at least
two million persons at present infected with the disease, and that
should these hookworms be blotted out of existence, two million
incapables would be changed into two million active Americans, ready to
raise the southern districts to a commercial elevation which their
natural resources seem to justify.
The treatment of the hookworm disease is simple, and the donation by Mr.
Rockefeller of $2,000,000 is intended to be sufficient to furnish the
opportunity at least for a complete cure of all the cases. It has been
found that a small dose of a preparation of thyme known as thymol
stupefies the parasites with which it comes in contact, so that they
unloose their claws and are set free in the intestine after its use. A
dose of epsom salts shortly after clears them out, and except for the
loss of blood, the disease is finished. Sometimes, however, in
long-continued cases the worms have penetrated so far into the membrane
that the use of thymol cannot withdraw them. In fact, in autopsies, it
has been found necessary to take tweezers and to use considerable force
in order to pull them out.
The prevention of the disease is really the cure of the disease, an
apparently simple matter, as already described. An improvement of
sanitary conditions so as to make impossible further pollution of the
soil should be also undertaken. Wherever the disease has prevailed in
this country or in Europe, it has been because of an utter neglect and
disregard of what are now known as ordinary sanitary conveniences, and
the report of the Country Life Commission, although many charges were
made against the conditions of living in different parts of the country,
was far from telling the whole story in the matter of the shortcomings
in parts of the southern states. There is, therefore, every reason why
the farmer and others living in the country should be urged to make
themselves comfortable with all known modern sanitary appliances. This
is desirable, first, for the sake of others on whom their sins of
unhygienic living might be visited, and then for their own sake, because
there such sins would also have an effect to a degree tenfold more
severe.
_Pellagra._
Another disease peculiar to country life, and which has only within the
last few years been recognized, is known as pellagra. Not yet is it even
known through what agency the disease is transmitted, but it has been
beyond question established that in some way corn is responsible for its
spread. Apparently, spoiled corn is necessary, and while presumably the
corn itself is not the agent, the parasite or organism that is
responsible lives only on corn which has been spoiled. Scientists have
long worked on the disease, and it would be a merely speculative
pursuit, one of interest to scientists and medical men only, except for
the fact that within the last few years it has broken out in this
country and is increasing to a most alarming degree. The disease itself
is almost hopeless when once established, physicians being yet utterly
unable to grapple with it; and while in Italy, Spain, and Egypt it has
been known for a century, there is still a death-rate of over 60 per
cent, and these deaths occur after most horrible suffering and agony.
As in rabies, the parasite, if it is a parasite, acts through a poison
which penetrates to the nervous centers, producing mental disturbances
culminating in an active insanity. At the same time, the agent attacks
the skin, whence its name "pell'agra," which means "rough skin," so that
the body appears as if it were affected with a severe attack of eczema,
large patches of skin peeling off and leaving the raw surface. In fact,
in one of the Illinois hospitals, only a few years ago, some insane
persons, infected with this disease, died, and because the effect of the
disease on the skin was not known, the nurse in charge was accused of
scalding the patients with boiling water, the appearance of the skin
being the only proof. The nurse was discharged, although, without doubt,
she was innocent, and the appearance of the skin was due solely to the
disease. It has been estimated that there are at present in the United
States five thousand victims of pellagra, with the number constantly
increasing, although physicians of standing make estimates largely in
excess of this.
Apparently preventive measures must consist in eliminating the
possibility of the use of spoiled corn. Indications are that the disease
appears only when such corn has been used, and in parts of Mexico where
corn is always roasted before being used, pellagra is never known. It
has been described as a disease of the poor, because the disease has
flourished chiefly in districts where poverty is so extreme that corn,
and spoiled corn at that, is the only food within reach. Usually, where
a mixed diet with meat is possible, pellagra never appears. In other
places, as in Italy, where the peasants live on a porridge of corn meal
cooked in great potfuls, a week's supply at a time, and during the week
exposed to dirt and flies and often spoiled before eating, pellagra is
most common. Experiments have shown that in these districts, by
excluding corn from the diet and furnishing a substantial fare, the
disease has been banished. Unfortunately, the taint of the disease
passes from parent to child and even to the third and fourth generation,
and the physical deformities commonly seen in pellagrous districts are
due to this hereditary taint. Dr. Babcock, Superintendent of the City
Hospital at Columbia, South Carolina, after discussing the disease, sums
up by saying, "Pellagra is a fact, and the United States is facing one
of the great sanitary problems of modern times."
_Bubonic plague._
The bubonic plague, or "The plague," as the importance of the disease
has caused it to be called, is one of the oldest of known epidemics. In
the third century it spread through the Roman Empire, destroying in many
portions of the country nearly one-half of the people. Its immediate
origin is a bacillus causing symptoms similar to blood poisoning,
although in some cases, where the lungs are attacked, the disease has
some of the characteristics of pneumonia.
A description of this disease is included here because, while bacterial
in its nature, it is transmitted largely, if not entirely, by fleas and
by a particular species of flea known as the rat flea. These fleas
harbor the plague bacilli in their stomachs and inject them into the
bodies of those they bite, in the same way that the anopheles or
stegomyia mosquito transmits malaria or yellow fever. Elaborate
experiments made in India in 1906 show conclusively that close contact
of plague-infected animals with healthy animals does not give rise to
any epidemic, so long as the passage of fleas from infected to healthy
animals is prevented. When opportunity, however, was given for fleas to
pass from one animal to another, the bacillus and the disease was
generally carried over. It has also been found that while this species
of fleas have their normal residence on the body of rats, they will also
desert a rat for man, if the infected rat is dying and no healthy rat is
in the vicinity to receive them. It is, then, obvious that to eliminate
the disease, the most direct and positive course is to destroy the rats
which are the home of the disease.
In India, where the plague appeared in 1896, causing about 300 deaths,
it rapidly increased in virulence until in 1907 it caused 1,200,000
deaths. The ports of the Pacific coast became much alarmed, and when
cases of the disease were actually found in San Francisco in 1906, the
matter was so terrifying that the United States Marine Hospital Service
was at once instructed to stamp out the disease if possible. This
procedure was directed almost entirely against rats. Deposits of garbage
on which rats might feed were removed, rat runs and burrows were
destroyed and filled in, and stables, granaries, markets, and cellars
where rats might abound were made ratproof by means of concrete. Rats
were trapped and poisoned by the thousand, nearly a million being thus
disposed of. As a result of such thorough work, the plague was stayed,
and in 1909 not a single case of the disease among human beings was
found, and although 93,558 rats captured were examined, only four cases
of rat plague were found.
In southern California, however, the fleas deserted the rats for ground
squirrels, and one county in particular, Contra Costa County, had an
epidemic which caused the squirrels to die by the thousands. The
attention of the scientists was thus turned to the squirrel as a host of
the flea, and a warfare similar to that against the rat has been for a
year past carried on against the infected squirrels. Between September
24, 1908, and April 12, 1909, 4722 ground squirrels were killed and
examined for plague infection, and from June 4 to August 13, 1909, the
work being continued, 178 squirrels were found to have the plague.
Now that the relation between fleas and their hosts and the transmission
of the disease is known, there need be but little fear in the future of
this old enemy of man again getting control and spreading without
hindrance throughout a whole country.