yellowish-white, thickish, band-like worm, ranging from six to twenty
feet or more in length. The head, about the size of a yellow
mustard-seed, is rounded quadrate and provided with four equidistant
hemispherical suckers. Succeeding the head is a short, slightly
narrower, flattened neck, which merges into the gradually widening and
segmented body. The segments, at first narrow fore and aft and several
times wider than the length, become successively larger,
proportionately longer, more distinct, and quadrate in outline; and
finally the length may exceed the breadth two or three times. A
full-grown tape-worm may possess twelve hundred segments and more, and
specimens are recorded as reaching a length of thirty feet. The larger
segments measure from a quarter of an inch to an inch long and from
three to four lines wide. The larger or riper segments exhibit on one
border, irregularly alternating on the two sides, at or near the
middle, a papilla in which is the external aperture of the genital
apparatus. In the fully-ripe segments the uterus, distended with eggs,
may be obscurely seen through the wall of the body, but is rendered
more visible by drying the segments, moderately compressed, between two
pieces of glass. It appears as a long, narrow, white or brownish median
line or tube, giving off laterally numerous short, transverse, more or
less branching tubes.
The worm in its usual position lies along the course of the intestine
in loose coils, and exhibits lively movements, alternately shortening
and elongating, expanding and contracting the head, and protruding and
retracting the suckers. The ripe segments spontaneously detach
themselves, and may be found scattered along the large intestine ready
to be discharged with the excrement, or, as is sometimes the case, they
may spontaneously creep from the anus. Rarely more than a single worm
infests a person at the time. The species is of rapid growth. According
to Perroncito, quoted by Cobbold, a mature worm was reared from a beef
measle, swallowed by a student, in fifty-four days.
It is estimated that the number of eggs in the mature segments of the
beef tape-worm amounts to about 35,000. As the full-grown worm may
consist of 1200 segments, and there is reason to believe these are
renewed several times annually, we learn that the whole number of eggs
produced by a single individual is enormous. The ripe segments,
attached to the parent or becoming spontaneously detached, lay their
eggs in the intestine to be discharged with the feces. When more or
less emptied they shrink and appear reduced in size, and in this
condition are expelled or spontaneously creep from the anus. If the
ripe segments are forcibly expelled and are alive, they will lay their
eggs in the feces externally. The ripe eggs are brown, oval, about 0.03
mm. long, and have a thick shell, with an outer vertically striated
envelope.
As previously intimated, the common source of the beef tape-worm in man
is the use of raw or insufficiently cooked beef affected with measles.
The ox becomes infested by swallowing the eggs, or, it may be, even the
entire segment, of a tape-worm deposited with feces in the {935}
pastures of cattle. The measles usually occur in the muscles, including
the heart, though they have also been noticed in the liver and lungs.
They appear, in beef, as oval, whitish bodies from the size of a
mustard-seed to that of a pea. They consist of a sac of connective
tissue containing the larval tape-worm or cysticercus. Measles under
ordinary circumstances are seldom noticed in beef, and when they occur
are commonly few in number.
According to the latest authorities--Leuckart, Cobbold, Stein, and
others--the beef tape-worm is the most common of the cestodes which
infest man. Until within about thirty years it was generally not
distinguished from the pork tape-worm, and this was accordingly
regarded as the most common human species. Since the writer distinctly
recognized the beef tape-worm within the last twenty years, all the
specimens of Tæniæ, from people of Philadelphia and its vicinity, that
have been submitted to him for examination--perhaps in all about
fifty--have appeared to belong solely to Tænia saginata. The prevalence
of this species with us is no doubt due to the common custom of eating
underdone or too rare beef, while the pork tape-worm is comparatively
rare, as with us pork is only used in a well-cooked condition.
* * * * *
TÆNIA SOLIUM.--SYNONYMS: The Pork tape-worm; Solitary tape-worm; Armed
tape-worm.
Larval condition: Cysticercus cellulosæ; Pork measle-worm.
Until a recent period this species was generally regarded as the most
common tape-worm of man--a view which in great measure was due to the
circumstance that the beef tape-worm was not distinguished from it. It
was called the solitary tape-worm, still expressed by the specific
name, from the impression that it rarely occurred otherwise than single
at a time in a person. This has also proved to be incorrect, likewise
due to the two kinds of tape-worms having been confounded together; for
while the beef tape-worm most commonly occurs solitary, the pork
tape-worm not unfrequently occurs with several together.
The species is now appropriately named the pork tape-worm, as
indicating its common source--pork used as food. The frequency of the
parasite is proportioned to the prevalence of the custom of using pork
in a raw or imperfectly cooked state, conjoined with that of depositing
excrement where it may be accessible to hogs. In the mature condition
the pork tape-worm is peculiar to man and lives in the small intestine,
but in the larval condition, though especially infesting the hog, it
also occasionally infests man, and lives in any organs of the body, but
mostly the muscles, liver, and lungs.
The mature pork tape-worm, as commonly seen, is a soft white, thin,
band-like worm, from five to ten feet long and about four lines where
widest. The head is spheroid, about the size of that of an ordinary
pin, and smaller than that of the beef tape-worm. It is furnished with
four hemispherical cup-like suckers, and the summit forms a blunt
papilla armed with a double circle of twenty-five or twenty-six hooks.
The neck is narrow, thread-like, about an inch long, and merges into
the segmented body, which gradually widens to the extent mentioned. The
segments, at first much wider than long, as they successively enlarge
also become more distinct and proportionately longer, so that the more
{936} posterior ripe ones are as long as they are wide, and often
longer, though not to the same degree as in the beef tape-worm. The
genital papilla, with its external aperture, is marginal as in the
latter. The fully-developed uterus is quite distinctive in character
from that of the beef tape-worm. The median tube is coarser, and the
lateral branches are likewise coarser, much fewer--half the number or
fewer--less branched, and less crowded. The ripe and often
spontaneously detached segments are commonly longer than broad, more or
less elliptical in outline, with truncated ends, and usually measure
about half an inch in length by about a third in breadth. The ripe eggs
resemble those of the beef tape-worm, but are usually spheroid in
shape.
The common source of the pork tape-worm is pork affected with measles
eaten in the raw or insufficiently cooked state. The hog becomes
affected with measles when it has access to human excrement containing
eggs and ripe segments of the tape-worm, which it eats with avidity.
The eggs, with their already developed embryos, when swallowed, undergo
the same series of transformations and course as those indicated in the
account of the beef tape-worm. Pork affected with measles is much more
common than beef affected in the same way, and is frequently a subject
of ordinary observation. From the difference in habit of the hog and ox
this is what might have been suspected; and the fact that the beef
tape-worm is more common than the pork tape-worm is to be explained
from the circumstance that fresh beef is in more general use than pork,
and is usually employed less thoroughly cooked.
The pork measles are commonly seen as round or oval, hard, whitish
bodies, from the size of a hempseed to that of a pea, imbedded in the
connective tissue of the muscles or flesh. The measle consists of a sac
of connective tissue enclosing the scolex or larval tape-worm, which
resembles that of the beef tape-worm, but differs especially in the
possession of a double circlet of hooks to the head, as in the adult
worm. The scolex has long been known, and was regarded as a distinct
parasite, with the name of Cysticercus cellulosæ. When fresh pork
measles are swallowed by man they are digested in the stomach, and the
cysticercus or scolex is released and passes into the small intestine.
Here, attaching itself to the mucous membrane by means of its suckers
and crown of hooks, it rapidly develops and grows into the adult
tape-worm. In this condition it lies in loose folds along the
intestine, to which it clings so tenaciously that commonly the neck
gives way when the greater part of the worm is forcibly detached by the
use of medicines. Fragments, consisting of the more mature segments,
frequently appear detached from the posterior part of the worm, and the
fully-ripe segments may be seen scattered singly in the course of the
large intestine. The isolated segments are thinner and more translucent
than those of the beef tape-worm, and in this condition are discharged
with the feces, but may also spontaneously creep from the anus, though
seldom as compared with the other species.
Experiments repeatedly made by swallowing pork measles prove that the
mature tape-worm may be developed in the course of three months. The
length of life attained by it under favorable circumstances is
uncertain, but it probably continues a dozen years or more.
The scolex of the pork tape-worm, or the cysticercus, so common in the
hog, is also less frequently a parasite of man, and in this condition
is a {937} more potent agent of danger than in its ordinary or mature
state. The infection is due to the introduction of eggs or mature
segments of the tape-worm into the stomach--a circumstance which may
readily occur through handling these objects and transferring them to
the mouth, or more rarely perhaps by their transference from the
intestine into the stomach through vomiting.
In the measle form the parasite may occur in any organ of the body, but
is mostly found in the muscles and subcutaneous tissue. Its
pathological significance depends on its number and position. Located
in the nerve-centres, it may occasion the most serious consequences.
Usually it occurs in small numbers and gives rise to no obvious
inconvenience, and is only accidentally detected in dissection after
death. It appears to maintain its vitality for some years, but finally
dies, and undergoes degradation. Only when it can be detected in such
position as the interior of the eye or beneath the conjunctiva can the
patient be relieved by surgical aid. Elsewhere, even if its presence is
suspected, it is ordinarily beyond the reach of medical treatment. The
writer a few years since, in dissecting the body of a colored man to
illustrate his lectures on the muscles, found two living measles, of
which one was in the diaphragm and the other in the transversalis
muscle of the abdomen, but none were detected elsewhere. The parasite
unquestionably gave no inconvenience to its host during life.
* * * * *
Other species of Tænia which have been observed as parasitic in the
human intestine are mostly of rare occurrence.
* * * * *
TÆNIA CUCUMERINA, the common tape-worm of the dog, and TÆNIA ELLIPTICA,
the common tape-worm of the cat, are very much alike in appearance, and
are regarded by many authorities as the same species. They occur
frequently in considerable numbers in these animals, living in the
small intestine. They have also been occasionally found in man,
especially children.
It is a comparatively delicate worm, chain-like in appearance, ranging
from four inches to a foot in length. The head is provided with four
suckers and a prominent rostellum armed with about sixty hooks. The
neck and anterior part of the body are thread-like. The mature segments
are elliptical in outline or like a melon-seed, whence the name. There
is a double set of sexual organs, and a genital orifice occupies the
middle of both lateral margins of the segments. The ripe segments
become readily detached and creep actively in the intestine, and are
either expelled with the feces or they spontaneously creep from the
anus. The eggs are comparatively few and measure 0.05 mm.
Late researches appear to show that the eggs adhering to the hair about
the anus or elsewhere are eaten by lice of the same animals, and within
these insects undergo further development. The dog and cat,
subsequently swallowing the lice, infect themselves with the mature
worms. Thus also persons, especially children, from too great
familiarity with these animals, directly or through their food, may
likewise become infected.
* * * * *
TÆNIA NANA, the Dwarf tape-worm, has been observed but once. It was
discovered by Bilharz, in Egypt, in a boy who died of meningitis. It
{938} is a little worm, about half an inch in length, and occurred in
large numbers in the duodenum.
* * * * *
TÆNIA TENELLA.--This is another small species, which has been but once
observed. It is described by Cobbold, who suspects it to be derived
from measles of the sheep.
* * * * *
TÆNIA FLAVOPUNCTATA is also a small species, from eight to ten inches
long, with ripe joints about one millimeter long and from one and a
half to two millimeters broad. It is described by Weinland, and has
also been but once observed. A half-dozen specimens were discharged
from a healthy child, of nineteen months, in Boston, Mass.
Since the above was written the author has had the opportunity of
examining some little tape-worms which he suspects to be of the same
kind as the former. They occurred in the practice of T. V. Crandall in
Philadelphia, and were expelled from a child of three years of age
after the use of santonin. About a dozen fragments appear to have
pertained to three worms, from twelve to fifteen inches in length. The
head in all was lost. The anterior part of the body is thread-like, the
posterior part about two and a quarter millimeters wide. The width of
the joints is more than twice the length. The ripe joints are pale
brown, and are remarkable for the comparative simplicity of the uterus,
which is distended with brown eggs. A peculiarity of the worm is the
repeated but irregular alternation of fertile with sterile joints.[1]
[Footnote 1: _Amer. Journ. of Medical Sciences_, 1884, p. 110.]
The species is probably more common than might be supposed, and from
its small size, and perhaps harmless character, has generally escaped
notice.
* * * * *
TÆNIA MADAGASCARIENSIS.--This species, described by Davaine, is
imperfectly known. Fragments of the worm have been twice observed in
the Comoro Islands.
* * * * *
BOTHRIOCEPHALUS LATUS.--SYNONYMS: Dibothrium latum; Tænia lata; Broad
tape-worm.
This tape-worm, of another genus than the preceding, is a common
parasite of man in certain localities of Europe, but has not been found
as an indigenous product elsewhere. It occurs especially in Sweden and
Russia, East Prussia, Poland, and West Switzerland. In the latter
country it prevails to such an extent that it is reported that about
one-fourth of the inhabitants of Geneva are thus infested. Among the
tape-worms submitted to the writer from time to time for identification
a few years ago was a large specimen of Bothriocephalus latus, but it
proved to have been derived from a Swede who had arrived in this
country only a few months previously.
There are many species of Bothriocephalus, which in the adult condition
mainly live in fishes. The genus is distinguished from Tænia by many
points, chiefly in the form and construction of the head, the form of
the joints and uterus, and the position of the genital aperture, which
is situated centrally on one of the broad surfaces instead of the
lateral margin.
{939} The broad tape-worm is the largest of the tape-worms infesting
man, a full-grown specimen reaching to twenty-five feet in length with
a breadth of three-fourths of an inch, and consisting of upward of four
thousand segments. It is a soft, grayish, flat, band-like worm, with
head, neck, and segmented body holding the same proportions as in the
other tape-worms. The head is elongated, clavate, and is provided with
a long, narrow, elliptical sucker on each side. The narrower neck is
short and merges into the segmented body, which gradually widens to
half an inch or more. As the segments successively enlarge, they
increase proportionately to a greater extent in breadth, so that their
width for the most part measures from two to four times their length. A
few toward the end of the series become narrower and longer than those
in advance. In the ripe segments the uterus, distended with brownish
eggs, forms a central rosette-like group of pouches. The genital
aperture is central in the broad surface of the segments, and is always
on the same or ventral side.
The broad tape-worm inhabits the small intestine, and is usually found
single, but occasionally several together, and sometimes also in
association with one or both the other common tape-worms. The species
is also reported to be not infrequent in the dog.
Ripe portions of the broad tape-worm become detached in fragments of
variable length, to be discharged with the feces. The partially-emptied
appearance of the uteri in these fragments indicates the laying of the
eggs previous to the expulsion of the latter. The eggs are oval, of a
light-brown color, and measure about 0.07 mm. long. The shell at one
pole is furnished with an operculum or lid for the escape of the
embryo. This is developed subsequently to the discharge of the eggs
from the intestine. If the eggs are placed in water, in the course of
some months the embryos are developed and escape from the shell. The
embryo is a round or oval body furnished with three pairs of spicules,
as in that of the Tæniæ, but differs in possessing a ciliated envelope,
by means of which it freely swims about in the water. After some days
the embryo discards its envelope and creeps about in an amoeboid
manner. Further than this, until recently, the fate of the embryo was
unknown. Braun of St. Petersburg, after determining the presence of
scolices of Bothriocephalus in the muscles, liver, and organs of
generation of the pike, trout, and eel-pout, by feeding these to cats
and dogs succeeded in rearing worms which differed in no respect,
except in being smaller, from the Bothriocephalus latus of man. Such
being the case, it becomes evident that man may ordinarily become
infested with the parasite by eating raw or insufficiently cooked
fishes of the kind mentioned.
* * * * *
BOTHRIOCEPHALUS CORDATUS, described by Leuckart as a common species
infesting the dog in Greenland, has been reported as having once been
found in a woman. Böttger regards it as not distinct from
Bothriocephalus latus.
* * * * *
BOTHRIOCEPHALUS CRISTATUS.--This species, but once observed, is
described by Davaine. It was passed by a child in Paris, and the worm
was upward of nine feet in length.
* * * * *
SYMPTOMS OF TAPE-WORMS.--Whichever may be the species of {940}
tape-worm infesting the human intestine, the symptoms to which it gives
rise are mainly of the same character, modified of course in degree by
the size and number of the parasites and the susceptibilities of the
patient. Clinging by means of the head to the mucous membrane of the
intestine, and involved among the valvulæ conniventes and villi, the
worm may extend in loose folds along the greater part of the course of
the intestine or lie coiled in an elongate mass. Besides being rendered
evident from time to time by the discharge of segments or fragments,
the beef tape-worm especially sometimes introduces itself to the notice
of its host through the segments creeping from the anus. Sometimes
segments of tape-worms are vomited, especially in women; and the
exhibition in this way, especially of the pork tape-worm, is to be
deplored, for should segments be retained in the stomach the patient
becomes further liable to be affected with measles or cysticerci.
Some persons continue infested with a tape-worm a long time without
suspecting its existence and with little or no inconvenience, and
perhaps first become aware of its presence by the accidental discovery
of segments discharged from the bowels. Usually, however, the parasite
creates more or less disturbance, and not unfrequently occasions great
discomfort. The symptoms are both local and of a general nature.
Itching at the extremities of the alimentary canal and various
dyspeptic symptoms are common; uncomfortable sensations in the abdomen,
uneasiness, fulness or emptiness, feeling of movement attributed to the
worm, and colicky pains; disordered appetite, sometimes deficient,
oftener craving; paleness, discoloration around the eyes, furred
tongue, fetid breath, and sometimes emaciation; fulness of the
forehead, dull headache, buzzing in the ears, twitching of the face,
and dizziness; often uncomfortable feelings in the abdomen increased by
fasting, which are temporarily relieved by taking a full meal. Certain
kinds of food also at times appear to produce greater uneasiness,
apparently due to more than usual disturbance of the parasite. Symptoms
of a more grave character are sensations of fainting, chorea, and
epileptic fits. Others of a chlorotic and hysterical character are not
unfrequent, especially in women, who also may suffer more or less from
uterine disorder.
All the ordinary symptoms are quickly relieved by the expulsion of the
tape-worm--permanently if it is entirely removed, but temporarily, as
is frequently the case, when only the greater bulk of the parasite is
discharged and the head continues to remain securely attached to the
intestine and ready to renew its many-segmented body. The tape-worms
are capable of a wonderful amount of extension from traction without
detachment; and from the delicacy of the neck and the anterior part of
the body, and the action of medicine on the peristaltic motion of the
intestine, the posterior part of the worm, including its great bulk, is
most apt to be torn away and discharged, while the head remains. So
long as this is the case, and the worm has not been poisoned or killed,
the anterior portion grows, and thus the parasite is renewed and
accompanied by a return of all the former symptoms. Under the
appropriate treatment the evacuations of the patient should be
carefully inspected, so as to satisfy both physician and patient that
the parasite has been completely expelled. To properly examine the
evacuations, they should be repeatedly drenched with clear water, and
the sediment, after the settling {941} of the washings, must be
inspected. It is only when the physician has seen the head of the
parasite that he can reasonably ensure his patient a permanent cure.
* * * * *
TREATMENT.--To get rid of tape-worms many remedies have been employed,
though comparatively few retain a reputation for positive success. Some
act by powerfully operating on both bowels and worms, producing the
detachment and discharge of the latter without killing them, as is
often indicated in the lively movements they exhibit after their
expulsion. Others poison and kill the worms, and also cause their
detachment and expulsion from the bowel.
Before the administration of the appropriate medicine for tape-worms,
with the object of rendering it more effective it is advisable to bring
the alimentary canal into a condition which will render the parasites
most vulnerable. For this purpose fasting is to be recommended for
several days previously, and when food is used it should be in moderate
quantity, and of such a character as to leave little residue to
accumulate in the intestine. Wheat bread, the ordinary meats, milk and
coffee, are best, while the usual vegetables should be avoided.