parasites present and the quantity of blood they consume and cause to
be lost. Bad cases may end fatally in a few weeks, but generally the
disease lasts for months, and where the patient is provided with
abundance of good food it may continue for years.
The prognosis of the disease is rather unfavorable; if, however, the
nature of the affection is ascertained before it has greatly exhausted
the patient, and the parasites can be expelled, the result should be
favorable.
We have thus far obtained but little information as to the best
treatment for Anchylostomum. Calomel and turpentine have been
recommended, and, as these are most powerful vermicides, we have reason
to believe they would prove most effectual remedies.
In regard to the prophylaxis for Anchylostomum--and we may add in
general for all parasites which gain entrance to man through
drinking-water--all stagnant or standing waters should be filtered, so
as to remove any source of infection, whether by eggs or free embryos
of parasites or of larval forms existing within minute aquatic animals
which serve as intermediate hosts to parasites. Standing waters, such
as those of puddles, ditches, marshes, and ponds, more or less swarm
with minute animals, all of which may be entirely removed by
filtration. Even the water of cisterns and wells, if supplied from the
free surface of the country, may not be free from minute animals, and
especially eggs, and therefore requires filtration to be safe. Only
spring and freely-running water of rivers and creeks and of lakes is
commonly free from microscopic animals and their eggs, and therefore
devoid of all danger in these respects.
* * * * *
STRONGYLUS LONGEVAGINATUS; S. bronchialis.--This nematode has been only
once satisfactorily observed. Many occurred in the lungs of a boy in
Germany, but the real cause of his death was not stated. The female
worm is about an inch long, the male about five-eighths of an inch.
Certain worms previously discovered in the bronchial glands of a case
of phthisis, and described under the name of Hamularia lymphatica, are
regarded by Cobbold as the same with the former; but the descriptions
of the two render this improbable. Treutler's drawing of Hamularia, as
copied by Leuckart, looks like an Ascaris upside down.
* * * * *
{957} EUSTRONGYLUS GIGAS; Strongylus gigas; Palisade-worm;
Kidney-worm.--This worm, recorded in the catalogue of human parasites,
is doubtful as such. Pertaining to the same family as Anchylostomum, as
the common name indicates its usual habitation is the kidney. It is the
largest of the nematodes, and is a long, cylindrical red worm, slightly
tapering, and blunt at the ends. The mouth is enclosed by six rounded
labial papillæ. The caudal extremity of the male ends in an inverted
cup-like pouch, from which the penal spiculum protrudes. The female
commonly ranges from one to three feet in length and from a fourth to
nearly half an inch in thickness. The male ranges from six inches to a
foot in length and from one to three lines in thickness.
The mature parasite is common in many fish-eating mammals, from which
it is inferred that fishes are the intermediate host for the juvenile
condition of the worm. It is frequent in the wolf, dog, mink, weasel,
raccoon, otter, and seal. It also occurs in the hog, and is reported to
have occurred in the horse, ox, and man. Usually it is solitary, and
occupies one of the kidneys coiled upon itself. Under its influence the
kidney is atrophied and reduced to the condition of a capsule of
connective tissue, often containing bony spicules. It feeds on blood
and on the purulent matter resulting from the inflammation it produces.
The worm is occasionally found in other positions, as the mesentery,
the abdominal cavity, the intestine, liver, urinary bladder, and lungs,
but perhaps in most of these cases has been derived from its usual
habitation. In this country the writer has repeatedly observed the
kidney-worm in the mink, the dog, and the wolf. In one instance in the
former animal he found a female and a male associated together in one
kidney, which was reduced to the condition of a fibrous capsule
containing in its wall a large radiated plate of bone.
The cases on record of the occurrence of this formidable parasite in
man are of very early date, and are mostly doubtful as to the authentic
nature of the worm, and are all unsatisfactory as to the attendant
phenomena.
* * * * *
TRICHINA SPIRALIS.--The trichina, or flesh-worm, a minute nematode, is
a common parasite of man, and from its wide prevalence and results may
be regarded as the most dangerous of all. Perhaps from the earliest
ages it has been dealing death freely and indiscriminately to our kind
without its existence having been suspected until within the last
half-century. Frequently, the affection, now named trichinosis,
produced by its presence has been so prevalent in communities as to
appear epidemic. The parasite was first discovered, and is commonly
observed, as a little worm coiled up and imbedded in the flesh of man.
In the same manner it is frequently seen in the flesh of the hog. In
the adult or mature state it lives in the small intestine of both man
and the hog, but its duration of life in this position is comparatively
brief.
Trichinosis, or the disease induced by the introduction of trichinæ
into the intestinal canal and the migration thence into the voluntary
muscles, varies in symptoms and gravity with the number, condition, and
position of the parasites and the susceptibility of the patient. The
presence of trichinæ in the alimentary canal, though often accompanied
by violent symptoms, is comparatively free from danger, whereas in the
muscular {958} system they not only produce the greatest suffering, but
often the most disastrous results.
Man is ordinarily infected with the trichina by eating the raw or
insufficiently cooked meat of the hog, or pork in any of its varieties
of food. Infected meat often contains immense numbers of the parasite,
a single ounce at times being estimated to contain from 50,000 to
100,000 worms.
The trichina was first distinctly noticed in the muscles of the human
body by Paget in 1835, and was described by Owen with the name it now
bears. It was subsequently observed under the same circumstances by
other investigators. In 1846 the parasite was found by the writer in
the muscles of the hog, but neither he nor others for some time
afterward suspected the significance of the discovery. In 1860, Zenker
of Dresden treated a supposed case of typhus complicated with excessive
muscular pain and oedema. On post-mortem examination the muscles were
found swarming with trichinæ, and to these the affection altogether was
attributed. Nearly at the same time the investigations of Leuckart
confirmed the relationship of the parasites as the cause of the
disease. In 1862, Friederich first diagnosticated the affection and
experimentally determined the presence of the worms in the living
patient.
The trichina is also found infesting other animals of the same class
besides man and the hog, especially the rat, mouse, rabbit, cat, and
fox. Experiments further prove that mammals are generally more or less
susceptible to infection with the parasite, though some appear to
resist its extension to the muscular system, as in the case of the dog.
The horse, ox, and sheep exhibit little disposition to artificial
infection of the muscles, and hence from this circumstance and the
nature of the food of these animals they are rarely found to be
infested with trichinæ. In experiments on birds and lower classes of
animals, though trichinæ were ascertained to advance in development in
the intestine, they failed to invade the muscular system.
Ordinarily, it appears that while man is infected with trichinæ through
the hog, this animal becomes infected by eating infested rats, mice,
and cats, fragments of waste pork, and perhaps occasionally by feeding
on the excrements of infested animals.
The trichinæ occupying the muscles are immature, and it is only after
they are swallowed and the parasites are freed by digestion of the
envelopes and pass into the intestine that they undergo development to
sexual maturity. In this state the female is viviparous and gives birth
to a multitude of active embryos, which immediately commence to migrate
to the muscular system. As it is estimated that each female may give
birth to upward of a thousand embryos, it is readily conceived to what
an extent the body may become infested from eating a few ounces of
trichinous pork.
The immature or larval trichinæ are also distinguished as muscular, and
the sexually mature ones as intestinal, trichinæ, in accordance with
their position in the two principal conditions.
Muscular trichinæ vary in condition from the embryo, which works its
way among the muscular fibres or has obtained entrance into these, to
the coiled-up worm lying quiescent in a capsule imbedded among the
muscular fibres.
Infected flesh in the early state is scarcely distinguishable as such
with {959} the naked eye, but in old cases the trichina capsules become
imbued with calcareous matter, and are thus rendered visible as minute
white or grayish specks scattered through the red meat.
In the recent state of invasion the worms are found free among the
muscular fibres or within these. Later, they appear mostly solitary and
at rest, coiled within a fusiform mass of semi-liquid granular matter
resulting from the degradation of the muscular substance. Subsequently,
they become enclosed in an elliptical capsule, apparently derived from
the myolemma of the muscular fibre they had entered. The capsules,
situated among the bundles of sound muscular fibres, are arranged with
their long diameter parallel with the latter. The trichina capsules
commonly measure about one-fifth of a line long, and the coiled worm
within is scarcely a half-line long.
If muscular trichinæ remain with their host, after a year or more they
exhibit signs of decay. Commonly, little fat-globules appear at the
poles of the capsules, and these become the seat of calcareous deposit.
Finally, the worms die and undergo degeneration.
When meat with living trichina capsules is swallowed, the freed worms
pass into the intestine, and here in the course of four or five days
reach maturity.
The adult intestinal trichina is a minute, filiform white worm, thicker
behind and tapering forward. The female is about an eighth of an inch
long, and has the genital aperture at the anterior fourth of the body.
The male is little more than half the length of the former, and has the
caudal end provided with a pair of conical processes, between which is
the genital aperture.
The ripe female trichinæ give birth to living embryos, and continue the
function for about a month, after which they appear exhausted,
ordinarily die, and disappear from the intestinal canal. The new-born
embryos, about 1/200 of a line long, quickly leave the intestine to be
disseminated throughout the body. Penetrating the mucous membrane, they
probably enter the blood-vessels to be carried onward by the
blood-currents, and perhaps also, in part, directly migrate to their
destination in the muscles. The latter mode of progress is rendered the
more probable from the circumstance that the muscles contiguous to the
intestinal canal, as the diaphragm and those of the abdominal walls,
are commonly most abundantly infested with the parasites. In the
muscles of the limbs they are sometimes noticed to predominate toward
the extremities of the former, as if retarded in their course by the
tendinous connections.
It would appear that muscular trichinæ, to be capable of producing
infection--that is to say, of further development--must have reached a
certain stage, corresponding with the encapsulated condition, before
they are swallowed. In this stage they may remain within their host
probably for a year or two.
Children seem to suffer less in proportion to the quantity of
trichinous meat they eat than adults, and they appear less susceptible
to muscular invasion of the parasites. The difference is probably in a
measure due to the greater susceptibility of the intestinal canal and
the consequent production of more copious diarrhoea in children, with
more complete expulsion of the worms.
SYMPTOMS.--In general, the effect produced by eating trichinous meat
{960} is proportioned to the number and condition of the trichinæ
ingested and to the susceptibility of the patient. A few of the
parasites may pursue their entire career and die within their host
without ever exhibiting any obvious evidence of their presence.
Sometimes the symptoms of trichinosis are obscure or trifling,
sometimes sufficiently well marked, but moderate, and often they are
more or less striking and violent. The period of incubation of the
affection varies from a few hours to a week or more, and the duration
of the disease also varies--both in a measure proportioned to the
number and condition of the parasites.
In mild cases of trichinosis the patient may pass through the course of
the disease without being confined to bed, and in a few weeks may be
regarded as convalescent. The majority of cases pursue a slow course of
from six or seven weeks to three or four months. A fatal termination is
frequent, and is most common from the fourth to the sixth week, and
appears mainly to be due to the loss of respiratory power. Fatal cases
rarely happen after the seventh week.
From a few hours to a few days after eating trichinous meat the patient
may be seized with dyspeptic symptoms--nausea, cardialgia, flatulence,
eructations, and vomiting. These may be accompanied with complete loss
of appetite, excessive thirst, bad taste, and fetid breath. There is
also commonly a feeling of general uneasiness, with fulness of the
forehead or headache, and feeling of weakness and fatigue to exhaustion
or complete prostration. Neuralgic pains are felt in the abdomen and
limbs, and the muscles generally are more or less relaxed and flabby.
Violent disturbance of the alimentary canal occurs only when large
quantities of active trichinæ are taken with the food. The subsequent
symptoms, due to invasion of the muscular system, may, but do not
necessarily, accord in degree with the former.
Diarrhoea usually comes on early, and the evacuations, at first more
consistent, become thin and clay-colored, like those of typhus or like
the rice-water stools of cholera. In the severest cases the patient may
die in this stage from extreme exhaustion and with all the appearance
of cholera. Sometimes the diarrhoea subsides and gives place to
obstinate constipation.
The muscular symptoms induced by the invasion of the trichinæ may be
trifling or moderate, varying to a most violent character. They
commonly appear after a week, and later up to the sixth week. The
muscles become more or less swollen, hard and tender to the touch, or
highly painful under pressure. Motion is extremely painful, and the
patient usually lies in a helpless state with the limbs flexed--adults
on the back, children on the side. Difficulty, with pain, in chewing
and swallowing ensues, and even complete trismus, due to the presence
of the parasites in the muscles of mastication and deglutition.
Difficulty of breathing also arises from the presence of the trichinæ
in the respiratory muscles, especially the diaphragm and those of the
larynx. Even movement of the eyes is painful, due to the parasites in
the orbital muscles. Bronchial catarrh comes on early, attended with
hoarseness and asthmatic cough.
Fever may be absent in mild cases of trichinosis, but is considerable
in the severer forms, though not in the first few days. The pulse
accords with the increase of temperature.
Profuse sweating is a common symptom of the affection, commencing {961}
early and continuing throughout. Generally there is considerable
decrease in the quantity of urine, which is highly colored.
Adults suffer with insomnia, while the reverse state prevails in
children, who commonly lie in a soporose condition. Formication and
dilatation of the pupils are frequent symptoms.
Oedema is a characteristic and pathognomonic symptom of trichinosis,
and is seldom so slight as to escape attention. It commonly appears in
the eyelids and face about the end of the first week, and may disappear
after several days, to recur after several weeks. It usually commences
in the limbs in the second week, and is more marked and persistent, and
increases, especially in severe cases.
Peritoneal and pleuritic irritation and inflammation, with bronchitis
and pneumonia, are not unfrequent complications in the more aggravated
form of trichinosis.
Most cases of the disease reaching the seventh week advance in
convalescence, while those of mild character by this time have
recovered, except from the weakness and emaciation, which remain as
evidences of serious illness.
Trichinosis in children is distinguished by greater mildness, less
danger, abundant oedema, less muscular pain, a dormant condition, and
more rapid convalescence.
The distinct recognition of trichinosis is difficult in isolated cases,
but becomes more evident where it occurs in numbers, as in an entire
family or in large portions of a community. The proof that the patient
has partaken of trichinous pork helps to establish the diagnosis.
In the beginning of severe cases of the affection symptoms of a more or
less violent gastro-intestinal catarrh are commonly present, often
associated with slight fever and almost invariably excessive
perspiration. Muscular lameness, both in mild and severe cases, is an
early symptom. The disease is distinguished from cholera by the profuse
perspiration and the peculiar muscular symptoms; from ordinary
rheumatism by the gastro-intestinal catarrh and general exhaustion.
With the appearance of oedema of the eyelids and face at the end of a
week the diagnosis becomes more certain. The further progress of the
affection is so characteristic that its distinction can scarcely remain
in doubt. The general prostration, the violent muscular symptoms, the
bronchial catarrh, the hoarseness and dyspnoea, the profuse sweating,
and the sleeplessness, render the case pretty clear.
In the prognosis of the disease no positive conclusion can be derived
from the severity or early appearance of the initial symptoms.
Commonly, the more speedily they occur and the more violent they are,
the less favorable will be the prognosis, while the later they appear,
the more propitious it is. Long-continued diarrhoea is especially
unfavorable, while a profuse diarrhoea at the beginning is to be viewed
as a fortunate event. The prognosis is more favorable in cases in which
sleep and the appetite are maintained, and in those in which the
disturbance of the respiratory organs is slight. A favorable
termination of the affection is the rule with children.
TREATMENT.--The treatment of trichinosis is not generally promising in
favorable results. No means have yet been discovered to destroy or
remove trichinæ which have migrated from the intestinal canal. While
{962} the parasites continue within the latter we may have reasonable
hope of expelling them from the body by means of the usual remedies for
intestinal worms. Experience, however, with these remedies has not been
in accordance with expectations. In the mean time, until some more
potent vermicide is discovered applicable to the destruction and
removal of trichinæ from the intestine, we are disposed to place most
reliance on such purgatives as oil of turpentine and castor oil and
calomel and jalap. Subsequently, a good nutritive diet with wine is
recommended to preserve the life of the patient until the affection has
reached that period when the parasites become capsulated and there is
no longer danger from them as irritants.
As a preventive of trichinosis, besides the avoidance of pork or its
varied preparations of ham, sausages, etc. when it is known or
suspected they may be infested, thorough cooking of meats is a certain
means. A boiling temperature surely kills all animal parasites, but
care is requisite that large pieces of meat should be cooked
sufficiently long that the desired heat may extend to the interior
throughout. The writer may add that it was in a slice of boiled ham,
from which he had partly made his dinner, that he first discovered
trichina in the hog.
* * * * *
Of the nematode worms there are many species of comparatively long,
slender proportions, which constitute the family of Filaridæ. As
parasites they rarely occupy the interior of the intestinal canal,
except by way of transit, and live in most other organs and tissues of
the body of both vertebrate and invertebrate animals.
* * * * *
FILARIA MEDINENSIS.--SYNONYMS: Dracunculus; D. medinensis; Medina-worm;
Guinea-worm.
The Medina-worm has long been recognized as a parasite of man, and by
competent authorities has been regarded as the fiery serpent which
afflicted the children of Israel in the wilderness of Judea. It
prevails in the tropical regions of Africa and Asia, and thence has
been introduced into tropical America. It is ordinarily observed as a
long, white, cord-like worm, situated beneath the skin in any part of
the body, but mostly in the lower limbs, and especially in the vicinity
of the ankle. Though a frequent parasite, only the female is known. In
the mature condition it is nearly uniformly cylindrical, and ranges
from eighteen inches to three or four feet in length and less than a
line in thickness. The head end is rounded and furnished with a little
papillate plate, in the centre of which is situated a minute oral
aperture. The caudal end is conical and incurved. The intestinal canal
is atrophied and without an anal aperture. The coelum is mainly
occupied by a capacious uterus filled with free embryos. A generative
aperture appears also to be absent, and the young can only escape by
rupture of the parent.
Experiments made about a dozen years since in Turkestan by Fedschenko,
at the suggestion of Leuckart, have shown that when the embryos of the
Medina-worm are introduced into water containing the familiar little
crustacean cyclops, they penetrate into this, and within it undergo
transformation into the larval stage. The subsequent history of the
larval worms remains unknown, but from what we have learned of the
history of many parasitic worms it is reasonable to suppose that if
{963} the infested cyclops is swallowed in drinking-water, it may
explain the presence of the mature worm in the human body. The young
worms, liberated from their crustacean host by digestion in the
stomach, probably enter the intestine, and thence migrate to their
destination. In the young condition, advancing to maturity, the worms
have been found in all parts of the body except within the cranium and
eyeball. They appear to migrate in the course of the least-resisting
connective tissues, along the route of the principal blood-vessels,
until they reach the surface of the body.
Usually, a single worm is found in a person, though cases occur where
several, to a dozen or more, are present. Commonly, the parasite is
solitary, though two or three may be associated together. When deeply
seated the Medina-worm ordinarily produces but little discomfort,
though in some cases its movements are accompanied with more or less
severe pain. It also gives rise to inflammation and the formation of an
abscess, in the purulent matter of which the worm lies bathed. The
removal of the worm, when accessible, by the proper surgical aid is
followed by complete relief.
It is evident that filtration of the drinking-water would be a certain
prophylaxis for the Medina-worm.
* * * * *
FILARIA SANGUINIS.--SYNONYMS: Filaria sanguinis hominis, Lewis; F.
sanguinolenta; F. Bancrofti, Cobbold.