Part 160

The thorn-head worms in the mature condition are comparatively robust cylindrical worms, with a body-cavity or coelum, but devoid of mouth and alimentary canal. They are provided with a protrusile and retractile proboscis-like head armed with circular rows of recurved hooks, by which they firmly cling to the wall of the intestine of their host. The sexes are distinct. There are many species, which mostly in the mature state live in fishes. In the juvenile or larval condition they live in other animals, mostly crustaceans and insects. It is doubtful whether any species naturally infests man.

* * * * *

ECHINORHYNCHUS GIGAS.--The great thorn-head worm is a common parasite of the hog, living in the small intestine. It is a large white worm, the female of which reaches a foot in length, while the male is about one-third the size. It is doubtful whether it occurs as a human parasite, though a worm less than the fourth of an inch found in a man in Prague has been attributed to this species.

The Nematodes, or Thread-worms.

The nematodes, or thread-worms, are slender, cylindrical, and inarticulate, and usually more or less tapering toward one or both extremities. {950} They have a distinct coelum or body-cavity, with thick muscular walls limited by a transparent elastic, chitinous integument, which is sometimes more or less distinctly and regularly transversely wrinkled. The alimentary canal extends the length of the coelum, with the mouth at the anterior extremity, and usually an anus at or near the posterior extremity. In some forms in the mature condition the intestine is atrophied and the anus absent. The sexes are distinct, and commonly the male is very much smaller than the female. The organs of generation occupy the coelum along the sides of the intestine. The female aperture is commonly situated ventrally near or in advance of the middle of the body, while the male aperture is at or in the vicinity of the anus. Mostly, the worms are oviparous, but many are viviparous. The development is direct, and usually the transformations are inconspicuous, so that the embryos mostly differ but little from the parent, except in the absence of the generative apparatus.

* * * * *

OXYURIS VERMICULARIS.--SYNONYMS: Ascaris vermicularis; Seat-worm; Pin-worm; Maw-worm; Maggot-worm; Thread-worm; Ascarides.

The seat-worm is the most common intestinal parasite of man, prevails everywhere, and is peculiar to him. It is a lively, wriggling creature which inhabits the small and large intestines and feeds on their contents. It frequently occurs in large numbers together, and in such cases incessantly makes its appearance, associated with multitudes of eggs, in the evacuations.

The female, which is ordinarily seen alone in the greatest abundance, is a white cylindrical worm tapering toward both extremities. The head end is thickened, and is provided with three prominent labial papillæ enclosing the mouth. The posterior end extends from the anal aperture in a long and straight, narrow, conical, sharp-pointed tail. The double uterine tube, distended with eggs, terminates in a vagina, the external aperture of which is situated ventrally near the anterior third of the body. The smaller male hardly tapers behind, but is incurved and ends in a short, blunt, conical tail. The penis is a single chitinous spicule, the end of which is usually seen projecting from the cloacal aperture.

The young seat-worms, in various degrees of growth and development, and the mature males are chiefly to be met in the lower portion of the small intestine, while the pregnant and mature females chiefly occupy the cæcum.

The seat-worm is exceedingly prolific, it being estimated that a single ripe female contains from 10,000 to 12,000 eggs, and these, it is suspected, may be renewed several times before her functions become exhausted. From time to time the ripe females proceed along the large intestine to the rectum, in which position they lay most of their eggs. These are discharged, together with many of the worms, in the feces.

The eggs are ovoid in shape and about 0.05 mm. long. After they are laid under favorable conditions the embryos are rapidly developed. Left in water, they soon die.

The investigations of the helminthologists of the day make it appear that it is necessary that the eggs of the seat-worm should be swallowed {951} and pass through the stomach, in which the embryos are freed, before they can undergo development to sexual maturity. Moreover, observations go to show that infection may, and probably ordinarily does, occur from eggs scratched from the anus and conveyed to the mouth directly or by being applied to food from uncleanly hands. It is evident that itching of the anus, induced by the presence of the parasites in the rectum, often accompanied by itching of the nose and lips, may lead to alternate scratching of the parts and the transference of eggs from one to the other. Thus, too, uncleanly nurses who may be infested with seat-worms after scratching may handle food and infest children under their charge. Children are commonly more liable to the parasites than others, no doubt from the circumstance that they are less capable of avoiding the conditions favorable to infection. Seat-worms prevail in all conditions of society, but their prevalence is largely proportioned to the more or less uncleanly habits. Persons sleeping with others infested are liable to infection, especially if they are uncleanly and in the habit of eating in bed. Obvious hints to avoid the parasites are obtained by regarding the statements thus given.

SYMPTOMS.--The presence of a few seat-worms is usually attended with no obvious inconvenience, and they may remain unnoticed unless accidentally observed in the evacuations. The symptoms occasioned by them are in great measure proportioned to their quantity and the susceptibility of the patient. The most prominent symptom is excessive itching of the anus; often trifling or even absent during the day, it becomes very annoying and distressing in the evening or during the night. This periodic change appears to be due to the movement of the worms to the rectum, apparently induced by the position and repose of the patient and the increased warmth of the body in bed. Under these circumstances the patient attempts to relieve the incessant itching by scratching, and often by boring with the finger in the anus. In this way eggs become adherent to the finger-nails, under which they have been repeatedly detected, and may thus be inadvertently transferred to the mouth. Occasionally, some of the worms wander from the anus, and in women may thence penetrate into the vulva. The itching of the anus may induce more or less sexual irritation, which in the young may further lead to onanism and its attendant evils. Other symptoms of the presence of the parasites are itching of the nose and lips, restlessness in sleep, grinding of the teeth, startings, twitchings, and general nervous disturbance. When the worms are very numerous they may produce intestinal catarrh, with discharges of mucus, pain, and diarrhoea. In children especially they may give rise to more serious nervous symptoms, as epileptic fits and chorea.

TREATMENT.--Generally, persons are readily relieved of seat-worms. Epsom salt alone or with senna as a purgative, repeated once or twice, often answers to completely expel them. Castor oil, also alone or with a few drops of the oil of turpentine or of wormseed, is also an effectual remedy. The tincture of aloes, in the dose of from half a fluidounce to two fluidounces, once or twice repeated, the writer has found to fully answer the purpose. Besides the purgatives, medicated suppositories, in obstinate cases injections of olive oil, and enemata of a solution of castile soap introduced by means of an elastic tube, so as to wash out the entire length of the large intestine, may be employed.

* * * * *

{952} ASCARIS LUMBRICOIDES.--SYNONYMS: Round-worm; Long round-worm; Maw-worm; Lumbricus.

The round-worm is the largest of the nematodes which ordinarily infest man, and is second only in frequency to the seat-worm. It is a well-known parasite, and prevails everywhere in all conditions of society. It is less lively in its movements than the seat-worm, and is remarkable for possessing a peculiar disagreeable odor, which is independent of the medium in which it lives. It inhabits the small intestine and feeds on the contents. It also infests the hog and the ox.

The round-worm is cylindrical, reddish or brownish, and tapering toward both extremities. The head end terminates in three prominent labial papillæ surrounding the mouth, and the tail end is short and conical. The female, as commonly seen, ranges from six inches to a foot in length, and is about a fourth of an inch in thickness. The ovarian tubes are long, thread-like, and tortuous, and, with the shorter, nearly straight, and wider uterine tubes, contain many millions of eggs. The genital aperture is situated ventrally near the anterior third of the body. The male is about half the size of the female, but is capable of considerable extension, and the tail end is incurved. The penis consists of a pair of slender, clavate, chitinous spicules, the ends of which protrude from the cloacal aperture at the root of the tail.

The round-worm is exceedingly prolific, it being estimated that the genital tubes of a large mature female contain the enormous number of 60,000,000 of eggs. The ripe eggs are laid in the intestine, and are discharged with the evacuations in great numbers, and often in considerable masses together. They are oval, about 0.05 mm. in length, and are provided with a thick shell and an additional tuberculate albuminoid envelope, usually colored by the intestinal contents.

The eggs of the round-worm after being expelled from the body are very tenacious of life, and under ordinary favorable circumstances they may remain in a condition capable of development for several years. Experiments have shown that they have great power in resisting the destructive influences of heat and cold, dryness, and the agencies of decomposition. In water and moist earth they have been retained alive for a year or two. When ripe eggs are placed in water the development of the embryo is observed to proceed very slowly, and is only completed after five or six months. The embryo while still contained within the egg sheds its skin and becomes provided with a tooth-like spine to the head end. The smallest examples of reputed round-worms found in the human intestine measured only about a line in length.

The further history of the round-worm is unknown, nor has it yet been positively ascertained in what manner man becomes infected with the parasite. Repeated experiments, not only on the hog and other animals, but on man himself, go to show that he is not directly infected by swallowing the recently-laid ripe eggs. It is rendered probable that the eggs are swallowed by some common but yet unknown minute aquatic animal, within which the embryo may undergo further development, and in this condition may be swallowed by man in drinking-water. In confirmation of the view that man becomes infected in the latter way, Davaine remarks that the "people of Paris, who drink only filtered {953} water, are rarely infected with the round-worm, which is otherwise the case in the rural districts of France."

The round-worm is most prevalent in warm climates, and especially among the less-civilized peoples. The better classes among the more enlightened nations suffer comparatively little from the parasite, and it is the lower classes, especially the ill-fed and uncleanly, who are most afflicted. It is exceedingly frequent in the Orient, in Africa, the West Indies, and Brazil.

Most commonly, only a few round-worms--one, two, three, up to a dozen--occur together in the same person, but they often occur in considerable number, even to several hundreds. Not unfrequently they are found in association with seat-worms. They are more frequent and usually occur in greater abundance in children, perhaps in a measure due to the circumstance that they are less able to discriminate the conditions favorable to infection and avoided on other grounds by adults.

The natural and ordinary habitation of the round-worm is the small intestine, especially the jejunum, and it commonly only occurs in the large intestine, mostly dead, on the way to be discharged with the evacuations. Under disturbing circumstances, as the character of certain irritating food, the parasite is disposed to become restless and wander from its usual position. Not unfrequently it enters the stomach, and thence may ascend to the mouth or nose, and perhaps the first intimation of the presence of such an unwelcome guest is in its expulsion from the mouth. From the pharynx the worm may enter the larynx and trachea, or advance farther into the air-passages, giving rise to the usual symptoms of foreign bodies in these parts. Occasionally the parasite forces its way through the bile-ducts into the liver and gall-bladder, creating disturbance in those organs proportioned to the number and size of the worms and the extent of their progress. In the liver it may occasion inflammation and the formation of an abscess attended with all the usual symptoms of hepatitis. It has been reported that it may penetrate the intestinal wall and enter the peritoneal cavity, but it is generally regarded as doubtful whether the worm can do so in a healthy state of the intestine, but only where there may be ulceration or other similar condition.

SYMPTOMS.--The symptoms indicating the presence of the round-worm in the intestine vary with its numbers and with the age and susceptibility of the patient. In general, the presence of one or two worms is unattended with any marked disturbance, and is mostly unsuspected until the parasite is accidentally seen in the discharges. The ordinary symptoms are disordered appetite (usually increased), flatulence, hiccough, foul breath, dyspepsia, abdominal pains, itching at the extremities of the alimentary canal, furred tongue, darkening of the eyelids, and emaciation. The nervous symptoms are restlessness in sleep, unpleasant dreams, starting in fright, grating of the teeth, and muscular twitchings. In more aggravated cases, especially in children, epileptic fits may occur. If the parasites are numerous, they produce diarrhoea with copious mucus discharges, and may induce enteritis with all its attendant symptoms. When the worms wander into the stomach, they induce colic, nausea, retching, and vomiting, all of which disappear with the expulsion of the parasites.

TREATMENT.--The remedies employed for seat-worms often serve to {954} expel the round-worm, and not unfrequently the two are discharged together. Wormseed, or the seed of Chenopodium anthelminticum, has been a favorite remedy for the round-worm, especially in children. The dose in these cases is one or two scruples of the powdered seeds in electuary with syrup or molasses, administered in the morning before breakfast and at bedtime for three or four days. It should be followed by calomel or other brisk cathartic. The volatile oil, in the dose of from five to ten drops in emulsion, may be used in the same manner.

A much-extolled remedy to destroy and get rid of the round-worm is santonin, given in doses of from one-third to one and a half grains three or four times a day, the larger dose being used only for adults. It should be followed by a purgative, for which a dose of castor oil answers a good purpose.