Chapter LIX: Front Matter (59)

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.

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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.

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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.

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FILARIA SANGUINIS.--SYNONYMS: Filaria sanguinis hominis, Lewis; F. sanguinolenta; F. Bancrofti, Cobbold.

Another species of Filaria, a more dangerous parasite of man and indigenous to the tropics, is of frequent occurrence, though of comparatively recent discovery. It has been observed in India, Africa, Brazil, and the West Indies. It is commonly seen in the embryonic condition, living in the blood of patients affected with elephantiasis and certain other diseases, and is also found in the urine. In this early condition it is a minute worm, scarcely more than the 1/100 of an inch in length, and occurs together in immense numbers.

In the sexually mature condition the female filaria is a white hair-like worm three or four inches in length, living in the lymphatic vessels distally to the glands, especially in those of the lower limbs and scrotum. The embryos after leaving the parent pass into the lymphatic stream, and thence into the circulating blood. According to recent observations of Manson, they enter the blood in the evening and increase in number until midnight, after which they decrease and disappear by morning, from which time during the day they remain absent from the circulation. The investigations of the same authority have shown that when the blood of infected persons is sucked by mosquitoes these insects also imbibe the embryos, which subsequently undergo transformation in the mosquitoes into the larval state. In this condition the filariæ may be transferred to water, by drinking which man may become infected with the parasites. The larvæ introduced into the stomach appear thence to make their way to the lymphatics, within which they undergo further development to maturity, and thus remain a long time.

The presence of the worms in the lymphatics, with their numerous brood in the circulating blood, gives rise to hæmaturia and chyluria. As results of the obstruction of the lymphatic currents, the parasites induce inflammation, suppuration, lymphatic abscesses, buboes, lymphangiectasis, {964} oedema, ascites, chylous hydrocele, elephantiasis,[3] and certain cutaneous affections.

[Footnote 3: Several years since, with the view of ascertaining the presence of parasitic worms, the writer examined the blood of a case of elephantiasis under the charge of T. G. Morton, but none were detected. From what we have since been informed of the habits of Filaria sanguinis, the absence of the parasites may have its explanation in the circumstance that the blood examined was withdrawn in the daytime.]

TREATMENT.--While the treatment of the affection induced by the Filaria sanguinis is varied and uncertain, the prophylactic measures are obvious and certain. Under favorable conditions of bright light, high temperature, and abundant food the stagnant waters of tropical countries are especially prolific of the minute forms of animals which harbor parasites. It hence becomes evident that all such waters, whether obtained from puddles, ponds, tanks, or cisterns, should be filtered before being used for drinking. Boiling is also effectual in destroying all the animal life of waters, and thus rendering them innocuous so far as parasites are concerned.

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Several other species of Filaria have been found in the human body, but are little known and very rare in their occurrence.

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FILARIA LOA.--This species occurs in Western Africa, on the Gaboon River, and is perhaps more frequent than now commonly supposed. It is an active worm, little more than an inch in length, and is usually found beneath the conjunctiva of the eye. It probably also occupies other positions, and a missionary on the Gaboon informed the writer that he had extracted one from the back of one of his own fingers. Its presence produced an intense burning pain. The negroes are reported to extract the worm by means of a thorn. The worm has also been observed in Brazil and the West Indies.

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FILARIA RESTIFORMIS.--Under this name the writer recently described a large Filaria reported to have been withdrawn from the urethra of a man in West Virginia. It was obtained by C. L. Garnett, and sent, together with an account of the case, to the Army Medical Museum of Washington, where it is now preserved. It was a red cylindrical worm, twenty-six inches in length, tapering at the head, and thick, incurved, and obtusely rounded at the tail end.[4]

[Footnote 4: _Proceedings of the Academy of Natural Sciences_, Philada., 1880, p. 130.]

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FILARIA OCULI HUMANI; FILARIA LENTIS.--A few cases are on record of the occurrence of little worms in the aqueous humor and crystalline lens of the human eye, to which the accompanying names have been applied.

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FILARIA TRACHEALIS.--Recently some minute worms found by Rainey in the trachea and lungs have been described under this name.

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In conclusion, the writer acknowledges his indebtedness for much of the information of this article to the articles on "Intestinal Parasites" and "Diseases from Migratory Parasites" in _Ziemssen's Cyclopædia of the Practice of Medicine_, and to Glazier's _Report on Trichina and Trichinosis_.

{965}

DISEASES OF THE LIVER.

BY ROBERTS BARTHOLOW, A.M., M.D., LL.D.