Other tomes: NEMAQ1915
Definition.—An infectious disease, generally recognized as caused by a micro-organism, the bacillus tuberculosis of Koch, and characterized by the formation of small nodular bodies, tubercles, varying from the size of a millet-seed to that of a mustard-seed, or even larger. They may infiltrate the general tissues, miliary tuberculosis, or, aggregating, form tubercular masses. These bodies undergo caseation, followed by ulceration or, more rarely, calcification.
History.—Could one write the history of tuberculosis in full, he would chronicle more suffering, more distress, and more deaths from this lesion than from any other disease that flesh is heir to. For twenty-five centuries this foe of the human race has steadily marched the highways of life, his victims increasing in numbers with the advance of years, and the twentieth century is compelled to record the awful fact that, notwithstanding our great advance in hygienic and sanitary measures, and notwithstanding our increased knowledge of this devastating scourge, and all our prophylactic means, one-seventh of all deaths recorded are due to this disease.
Its habitat is found all over the world. Previous to 1810 the study of this disease had been principally a clinical one, and was regarded as a suppurative process, but with the advent of Bayle and his pupil, Laennec, the tubercle was studied as a distinct, anatomical growth. The cheesy gland gave way to a distinct nodule or tubercle.
From this new era its development has been more rapid. In 1865, Villemen startled the medical world with his experiments on rabbits and guinea-pigs. He inoculated these innocent victims of science with cheesy products and tubercular particles, and invariably produced tuberculosis, proving beyond all doubt its infectious character. He writes, "Tuberculosis is the effect of a specific causal agent, a virus." Repeated experiments by other investigators confirmed its infectious character, and from this time forth the search began for the infecting cause.
This Koch announced to the expectant world March 24, 1882, before the Physiological Society of Berlin, as the bacillus tuberculosis. Since then the profession has largely acknowledged the bacillus as the exciting cause, though some still contend the microorganism is the result and not the cause.
Zoological Distribution.—This disease, so fatal to mankind, is widely distributed among the animal world, especially domesticated animals; in fact, it is only found in wild animals after having been reduced to captivity, proving that environment is one of the predisposing causes of tuberculosis.
Of domestic animals, cattle are by far the most frequently affected, especially dairy cattle. Dr. Carpenter stated before the British Medical Association, held in Glasgow in 1880, that he was informed by a London meat inspector that 80 per cent of the meat sold in the London markets was tuberculous, and that, if this were all condemned, the inhabitants could not be fed. While this statement is most likely exaggerated, it shows that it is extremely common in cattle.
Swine are next in order of frequency, while sheep and goats are almost free from it. The horse is not often affected, though not exempt. Fowls are frequently troubled, though the tuberculous material is of a milder and less infectious character. Monkeys, when brought into captivity, are peculiarly susceptible, Forbes stating that 43 per cent dying in the London Zoological Gardens succumb to tuberculosis. Dogs and cats, for a long time considered proof against its ravages, are now found tuberculous, most likely from their close association with man. Rabbits and guinea-pigs, when domesticated, soon show the same tendency.
Geographical Distribution.—Tuberculosis is the most universal of all diseases, and is to be found in all parts of the world, perhaps more extensively in warm climates than cold; however, the local conditions figure more prominently than climate. Wherever large masses of people congregate, there tuberculosis prevails.
Altitude has a more deterring influence on tuberculosis than latitude, and at one time it was supposed that the high mountain regions' were exempt; and while the condition of the atmosphere is undoubtedly purer and more fatal to the bacillus, yet the fact, that the mountainous regions are more sparsely settled than the valleys, is not to be overlooked, and were the summits of the highest ranges densely settled, we would, in all probability, find the disease very prevalent. Cities, then, with their teeming thousands, where many are crowded into close quarters, where the sun never enters, where foul and dark quarters house the submerged half, where malnutrition is the rule, and the unhygienic surrounding breeds disease,—these are the plague-spots of tuberculosis, and these conditions are found, be it hot or cold, in valley or on mountain-top, tuberculosis will be found.
Etiology.—Predisposing Causes.—Heredity.—That a child born of tuberculous parents is very prone to become tuberculous has been recognized by the profession in all times, though till very recently it was denied that a child ever came into the world with tubercles already developed. It was believed that a child simply inherited an enfeebled vitality, which was unable to resist the encroachments of the specific infection; in other words, they furnished the soil for the reception and development of the virus, whatever that may be.
Lehmen, however, records a case of undoubted intra-uterine infection, and, as proof, found tubercles, in which the bacilli were found in great numbers, in the spleen, lungs, and liver of a child who died one day after birth, the mother having died three days after delivery, with tubercular meningitis.
Pregnant animals have been inoculated, and the offspring found to be tuberculous at birth. While this is undoubtedly true in rare cases, the fact is apparent to all medical observers that the heritage bequeathed by turberculous parents, is a feeble vitality, feeble digestion, feeble assimilation, resulting in malnutrition—conditions favorable for the development of the disease.
Race.—Race is quite a factor in the receptivity of the infectious material. In the negro tuberculosis occurs more than twice as often as in the white race. The Indian is also very susceptible to its ravages, while Sears found 50 per cent of his cases to be of Irish descent. Perhaps the least susceptible of all peoples are the Hebrews, and no doubt their mode of life, which has been taught from generation to generation ever since Moses left his incomparable laws to his people, is largely responsible for this exemption.
Previous infectious diseases, such as la grippe, chronic bronchitis, measles, whooping-cough, typhoid fever, diabetes, etc., are often followed by tuberculosis. They furnish the soil, which only needs the planting of the seed for its development. Children begotten of syphilitic and cancerous parents come into the world handicapped by a feeble vitality, and the conditions are favorable for tuberculosis.
Environment.—The surroundings, habits, and occupations also figure prominently as predisposing causes. Among that large class of the human race, known as the submerged half, their method of living is conducive to the disease. Herded together in close quarters, where the sun never finds its way, where foul air reeks with the poison given off from the filthy inhabitants, and where wholesome food is an unknown quantity, we find all the conditions favorable for the disease.
Dissipations of all kinds also tend to produce it, while occupations that are attended by inhaling irritant particles, render the subject peculiarly liable. Summing up the predisposing causes, we find that,—whether the result of heredity, such as tuberculous, syphilitic, or cancerous offspring, or from environment—poverty, drunkenness, or occupation, or from previous diseases, whether catarrhal or infectious,—they all produce the same result; viz., an enfeebled vitality, a poorly elaborated blood and feeble resisting power; and when the infectious material, whatever it may be, gains entrance into the system, the battle begins. The conservative forces of the body are marshaled for the fray, the leukocyte or phagocyte against the parasite. The weak succumbs to the strong, the bacilli come off victorious, and tuberculosis is established. The vitality having been reduced, the contest is a short one.
Exciting Cause.—The bacillus tuberculosis of Koch is now generally recognized as the exciting cause. This organism is a slender, rod-shaped body, straight or slightly curved, and, in rare instances, branched. Its average length is from one and one-half to three and one-half microns, or one-half the diameter of a red-blood corpuscle. After staining, it presents a beady appearance, which may be due to the presence of spores. (See frontispiece.)
It stains slowly with the basic aniline dyes, and what is peculiarly characteristic is its resistance to decolorizing agents, such as a twenty-per-cent solution of sulphuric or nitric acid, the bacillus of leprosy being the only other micro-organism possessing this same characteristic. It may be grown on blood serum, glycerin, agar, bouillon, or potato, but more easily on blood serum, which must be kept at 98°, the temperature of the body. It requires about two weeks for their development, when colonies appear on the culture medium in the form of thin, grayish masses of scales.
Its vital tenacity is also characteristic, and, whether inside or outside the body, has great resisting power. These bacilli survive freezing and desiccation, and live indefinitely outside the body. In the body they are found in all tubercular masses, though in varying quantity, the greatest numbers being found in actively forming tubercle. Should a tubercular mass open into a vein or lymph tract, they will be found distributed to every tissue of the body.
Outside the body they are found principally in the sputum. Nuttall has estimated that several billion are thrown off daily by a phthisical patient during the advanced stage. The sputum drying, is reduced to dust by the friction that is constantly going on, and this dust permeates the atmosphere everywhere, settles upon furniture, draperies, carpets, the bed-linen, in fact, upon every article in the home of the afflicted, as well as upon walls and ceilings. When this dust is dislodged, it again floats in the air and is even then a source of danger.
The bacillus may be found in quite large numbers in the nares of people occupying or visiting these infected quarters. The chemical products resulting from the evolution of the bacillus and infected tissue has not yet been determined.
Mode of Infection.—The most frequent manner of receiving the infectious material is, undoubtedly, through respiration, and the minute bronchial tubes and lung are the first to show its ravages, although the nares and larynx follow in quick succession. At other times it gains entrance through the digestive apparatus, through infected meat and milk. Hereditary transmission, while possible (tubercles having been found in the fetus), is extremely rare and is most likely transmitted through the blood by way of the placenta. Inoculation may occur, by coming in direct contact, through cuts, fissures, excoriations, abrasions of any character, and generally assumes the character of tuberculosis of the skin.
Pathology.—Any organ of the body may be the seat of the disease, though some special parts are peculiarly susceptible. In the adult the lungs are the most frequently affected, while in children the lymph glands, joints, and intestines are the seat of election. The brain is also quite often the seat of the lesion, while the other viscera, liver, kidneys, spleen, and heart are less seldom affected.
Tubercle.—The invasion of a suitable soil by the bacilli or virus, induces characteristic phenomena of the tissue-cells. The poison, whatever it may be, excites the connective tissue-cells, there is an increased proliferation of these bodies, while out from the blood-vessels migrate polynuclear leukocytes. In or near the center of this mass of cells, a few cells enlarge, either by fusion or by proliferation of their nucleus, and become giant cells; others near them enlarge, and are called epithelial cells, and this mass of cells constitutes a small nodule or tubercle.
It is non-vascular, and early undergoes necrosis. The origin of the giant cells is not very clear, but they are generally regarded as being developed from phagocytes, and are found more abundantly where the bacilli are few in number. The tubercle at first is of a grayish color, but very soon this turns to a yellowish hue, owing to the destructive changes that take place.
Caseation.—Either from a poison, developed by the bacilli, or from some other source, necrosis of the cells occurs, forming a cheesy condition known as caseation: at a later period this breaks down, forming an abscess, the cavity being filled with purulent material.
Sclerosis or Fibrosis.—Sometimes nature comes to the rescue, and a secondary inflammation arises contiguous to the mass; there is cell proliferation, and the tubercular mass is enveloped in a capsule or fibrous tissue. Sometimes the transformation of the tubercle is complete, leaving a hard, indurated, fibrous nodule.
Calcification.—At other times there is a calcareous deposit, and the tubercular mass is said to undergo calcification. We thus see going on in tubercular patients a war of forces,—the constructive arrayed against the destructive; and only as the physician succeeds in building up the vital forces, enabling the tissues to resist the encroachments of the bacilli or toxins, will he be successful in benefiting his patient.
Miliary Tuberculosis.—When the infectious material is distributed to all parts of the body through the general blood supply, we have the formation of small nodules, millet-seed in size, formed in the various tissues, though the distribution is unequal, being abundant in some organs, while few in others. This form generally results from the breaking down of an old lesion, either a lymphatic gland, a pulmonary lesion, a tubercular bone-marrow, or the involvement of the liver or spleen.
Acute Miliary Tuberculosis.—Typhoid Form.—This form bears a striking resemblance to the infectious fevers, especially that of enteric fever, and unless the physician is familiar with the family history, where tuberculosis is well established, the diagnosis may not be confirmed till after death.
There is usually a period of incubation as in typhoid fever, though .somewhat different. The patient notices that he is growing more feeble, is losing flesh, and is taking on a cachectic appearance. The appetite fails or is capricious, and the tongue is dry or furred. After days, or sometimes weeks, of progressive decline, the patient becomes feverish, though the temperature chart shows it to be different from that of enteric fever. It is irregular, and does not show the gradual "step-ladder" rise the first week, so characteristic of typhoid. In fact, there may be subnormal morning temperature, and in rare cases it is afebrile.
There is generally some cough, though not more marked than often attends enteric fever. The respiration is more hurried, and the pulse is small and rapid, rarely dicrotic. There may be active delirium, though more often the patient grows dull, and is inclined to be passive, sleeping much of the time. There is nausea, and sometimes vomiting. In the early stages there is constipation, but as the disease progresses, there is diarrhea, and where there are tubercular ulcers of the intestines, there may be some hemorrhage. There may be tympanites. There is no eruption.
As the end approaches, there is the Cheyne-Stokes respiration. The spleen is somewhat enlarged, though not so marked as in typhoid. This form is fatal, and a favorable prognosis should never be given.
Diagnosis.—While there is a marked resemblance to enteric fever, if the physician is careful he need make but few mistakes. During the period of incubation, there is a normal or subnormal temperature, the patient loses flesh and strength, and there is nearly always some cough. When the fever makes its appearance, it is irregular in character, not uniform. There is no eruption. The respiration is generally more rapid and the pulse never dicrotic; and, lastly, though perhaps I should say first, there is the family history, which generally points to tuberculosis as a primal factor.
Pulmonary Form.—The general symptoms embrace most of those already mentioned, plus a more marked pulmonary group. The first symptom noticed, is a cough which may have existed for months, and been regarded as "cold on the chest," or, if a child, it frequently follows measles or whooping-cough. The fever is quite active, the temperature ranging from 103° to 104° or 105°. The respiration is increased in frequency, and is more or less labored. The face is inclined to be cyanotic, especially during or following an attack of dyspnea. The pulse is rapid and sometimes irregular. The cough resembles that of broncho-pneumonia, the expectoration is muco-purulent, and, if the inflammation is active, may be rusty-colored.
The physical signs are those of bronchitis or broncho-pneumonia. On auscultation, we hear sibilant rales, if there is but little secretion; or there may be fine, crepitant rales, telling of the gradual efracement of the air-cells by accumulation of mucus, or the deposit of tubercular material.
Diagnosis.—As in the preceding fever, the diagnosis is not easily made. The history of tuberculosis, coupled with the knowledge of a chronic cough, or following an attack of measles or whooping-cough, or diseased lymph glands; the marked dyspnea, the cyanotic appearance of lips, the high temperature, with rapid pulse,—are symptoms that point to this form of miliary tuberculosis.
Meningeal Form.—This form is perhaps more frequently found in acute tuberculosis than either of the other forms, or both combined. It occurs more frequently among children between the ages of two and six, though it may occur at any time of life. It was known by the older writers as hydrocephalus or dropsy of the brain.
The primary affection can very often be traced to tuberculosis of the lymph glands, while the exciting cause may be any of the infectious fevers incident to childhood, or the lesion may be regarded as arising from a fall.
The tubercles, especially in children, are deposited in the membranes at the base of the brain and in the sylvian fissure; becoming inflamed, a sero-fibrinous or fibro-purulent exudate is deposited, in which are found entangled the tubercles, varying in size from the microscopic to those plainly visible by the unaided eye. The meninges being affected accounts for the symptoms resembling meningitis.
The disease may begin more or less suddenly, with marked cerebral excitement, or convulsions may usher in a severe form that may prove fatal in a few days. As a rule, the disease has a course of from two to six weeks in children, and from three to five months in the adult.
Symptoms.—Prodromal Stage.—This stage may last for some weeks, especially if following measles or whooping-cough or the infectious diseases of childhood. The child is cross and fretful, restless at night, the appetite capricious, the breath is bad, and the tongue is coated. The bowels are usually constipated. The child has occasional spells of vomiting, which can not be traced to wrongs of the stomach. The patient loses flesh and strength, the face has a pinched appearance, the eyes are contracted, and the child, if old enough, complains of pain in the head.
Stage of Cerebral Excitement.—These symptoms grow more pronounced till the stage of excitement is fully ushered in. Chilly sensations, accompanied by severe headache and vomiting, may usher in this stage. The pain in the head is often of an intense character, the child uttering a sharp, piercing, hydrocephalic cry. The face is flushed, eyes bright, and pupils contracted. The screams of the child may persist for hours or until the child is completely exhausted.
Vomiting, so characteristic of cerebral irritation, is a prominent symptom. The bowels are obstinately constipated. The fever is usually not very high, the temperature ranging from 101° to 103°, though sometimes it may reach 104° or 105°. The pulse is small and rapid during the early days of the fever, but grows irregular as the disease advances. With the progress of the disease, owing no doubt to the pressure caused by the exudate, the cerebral symptoms become more passive. The patient becomes dull and drowsy, the pupils, which at first are contracted, now dilate, and the child sleeps with the eyes partly open. There is twitching of the muscles, and retraction of the head, especially when the spinal meninges are involved. The respiration may become, irregular and sighing.
Stage of Paralysis.—This stage occurs as the patient nears the end of the struggle. The patient can not be aroused, lies with the eyes partly closed, and there is involuntary twitching of tendons and muscles. Paralysis of the third nerve is most common, which may involve the face. Optic neuritis, together with strabismus or ptosis, is not uncommon.
Hemiplegia may occur. Osier records two cases of monoplegia of the right side of the face, with aphasia. In rare cases a typhoid state develops, tympanites occurring with diarrhea. The tongue becomes dry, brown, with sordes on teeth and lips; low delirium follows, the urine and feces are discharged involuntarily, the temperature falls, and death ends the scene.
Diagnosis.—A history of old foci, especially of the lymph glands, so far as can be learned; the irregular course of the fever; the excruciating pain in the head, attended by shrill screams; the constipated condition of the bowels; the coma, twitching of various groups of muscles; and finally paralysis of certain parts,—render the diagnosis not extremely difficult.
Prognosis.—The progress is decidedly unfavorable, and though cases of recovery have been recorded, it may have been that a mistaken diagnosis could have accounted for the favorable termination.