Tropical Diseases/Chapter 36

by Patrick Manson

Section IV.— INFECTIVE GRANULOMATOUS DISEASES

CHAPTER XXXVI

LEPROSY (ELEPHANTIASIS GRÆCORUM)

Definition.— A chronic infective granulomatous disease produced by a specific bacterium, and characterized by lesions of the skin, nerves, and viscera eventuating in local anæsthesia, ulceration, and a great variety of trophic lesions. After a long course it is almost invariably fatal.

History.— The many allusions in the oldest Chinese, Indian, Syrian, and Egyptian writings to a chronic, disfiguring, and fatal affection possessing well-marked and characteristic skin lesions, warrant us in concluding that the disease now known as leprosy was as common and familiar in the East in times of remotest antiquity as it is at the present day.

There is some evidence— necessarily of a negative character— that leprosy is of comparatively recent introduction into Europe. The earlier Greek .and Latin writers do not mention the disease. Hippocrates, who, had he been practically acquainted with leprosy, would undoubtedly have described it accurately and fully, makes but brief allusion to the subject. Aristotle is the first of the Greek writers to give an unequivocal description. We may infer, therefore, that the introduction of leprosy into Greece probably took place between the time of Hippocrates and that of Aristotle— that is to say, between 400 B.C. and 345 B.C. Most likely it came from Egypt. In the time of Celsus— 53 B.C. to A.D. 7— it was still a rare disease in Italy ; but during the earlier centuries of our era it increased there, and, probably following in the wake of the Roman conquests, it appears to have spread thence over the greater part, if not over the whole, of Europe. By the end of the seventh century it was well known in Spain, France, and Lombardy. There is a notice of its occurrence in Ireland in 432. As regards England, the first allusion to leprosy refers to about the year 950. The popular idea that it was brought to this country from the East by the returning Crusaders (circa 1098) is therefore incorrect; though, doubtless, the Crusaders, and the multiplicity of pilgrimages so much the fashion in the Middle Ages, and the destitution arising from the many wars of the period, had something to do with its rapid diffusion and great increase about this time.

So common was leprosy during the Middle Ages that the rulers and clergy of nearly all European states, becoming alarmed at its rapid extension and terrible ravages, took measures, by instituting leper asylums and enacting stringent laws for the segregation and isolation of lepers, to restrict the spread of what was speedily becoming almost a general calamity. These measures, based on what we now know to be a correct appreciation of the infectious nature of the disease, were ultimately crowned, in the case of most European countries, with almost complete success. Reaching its acme during the fourteenth century, leprosy then began to decline, although as regards Great Britain it did not finally disappear as an indigenous disease until the end of the eighteenth century. It died out first in England, later in Scotland the last British leper dying in Shetland in 1798. In Italy, France, Spain, Germany, and Russia the repressive measures were almost equally successful, although in these countries, in Greece, and in the Greek islands leprosy of indigenous origin is still occasionally to be seen. The only country in northern Europe in which at the present day it may be said to linger to any extent is Norway, where, in places, it is still by no means uncommon(in 1890 there were 1,100, in 1906 under 500 known lepers); but even here, under a system of segregation and comparative isolation— more humane perhaps in its application than that practised by our ancestors, although identical with it in principle— the disease is rapidly dying out.

Apart from Egypt, we know nothing of the early history of leprosy in Africa. We are equally ignorant as regards aboriginal America. The historians of the Spanish Conquest do not allude to it as a native disease; we appear, therefore, to be justified in concluding that the introduction of leprosy into the New World was probably effected by the Spaniards, or through the negroes in the days of the slave trade.

Rise of modern knowledge of leprosy.— The more important landmarks in our modern knowledge of leprosy are, first, the publication in 1848 of Danielssen and Boeck's "Traité de la Spedalskhed," in which, for the first time, the clinical features of the disease were carefully and critically described; second, the descriptions of the macroscopic and microscopic lesions —the leproma, the nerve lesions, and the lepra cell— by Virchow, Vandyke Carter, and many others; and last, the discovery in 1874 by Armauer Hansen of the specific cause of leprosy the Bacillus leprœ —a discovery which brings this disease into line with tuberculosis, and has given a much- needed precision to our ideas on the important subjects of heredity and contagion, and on other practical points bearing on the question of the leper as a source of public danger and on his treatment and management.

Geographical distribution.— Whatever may have been the case formerly, at the present day, with unimportant exceptions, leprosy is a disease more particularly of tropical and sub-tropical countries. So generally is it diffused in these that it would be more easy to specify the tropical countries in which leprosy has not, than to enumerate those in which it has been ascertained to exist. Moreover, it is probable that in many of the countries not yet positively known to harbour the disease it does really exist; for experience show that the endemic area of leprosy enlarges as our knowledge of the natives of the uncivilized regions of the earth becomes more intimate. It may be safely concluded, therefore, that, with the exception of a few insignificant islands, leprosy is an element, and often an important element, in the pathology of nearly all warm countries.

The only tropical country of any magnitude about which .we have anything like accurate leprosy statistics is India; and even in this instance the figures for many reasons— principally errors in diagnosis and concealment— are untrustworthy. According to the census of 1891, after making allowance for error, it is estimated that in British India there were 105,000 lepers in a population of 210,000,000— a ratio of about 5 in 10,000. Respecting China, of all countries probably the one in which there is the largest number of lepers, we have no figures to go by; but, judging from what is seen in the coast towns and treaty ports, the number of lepers is probably sensibly greater than in India. In Japan, in the Philippines, in Cochin China, in the Malay Peninsula, in the islands of the Eastern Archipelago and of the South Pacific, in Persia, Arabia, and Africa, the disease is common enough. The same may be said of- the West Indies and of the tropical regions of America.

As regards more temperate countries, we know that there are a considerable number of lepers at the Cape, a few in Australia (principally Chinese, but also a few Europeans), a few in San Francisco (Chinese). In Canada and in the United States there are also a few lepers of European blood, but their number is quite insignificant. In New Zealand, where leprosy used to be common among the Maoris, it has died out. There are a good many lepers in Iceland. Leprosy is also reported as existing among the aborigines of the Aleutian peninsula and Kamtchatka. In Great Britain and other European countries, particularly in the capital cities, lepers are not infrequently exhibited at medical societies; but, with rare exceptions, these cases are not of indigenous origin, most of them having contracted the disease abroad.

Though thus extensively diffused, leprosy is by no means equally prevalent throughout the wide area indicated. Thus in China it is comparatively rare in the northern provinces, excessively common in the southern. In India a similar caprice of distribution is noted; in Burdwan, for example, the proportion of lepers in 10,000 of the population is as high as 19.5, whereas in several other districts it is as low as 1.5 or even lower. This caprice of distribution does not seem to depend directly on climate, geological formation, or such-like physical conditions; for leprosy is found in mountainous districts, on the plains, on the coast, in the interior, in all varieties of climate, and on all kinds of geological strata. Social conditions, it would seem, have most to do in determining distribution; its endemic prevalence appearing to be bound up in some way with uncleanly habits, squalor, dirt, and poverty —not, be it noted, directly caused by these things, but associated with them.

Recent introduction.— An interesting and, from the etiological standpoint, an important circumstance about the geographical distribution of leprosy is its appearance and rapid spread in recent times in certain islands whose inhabitants, there is good reason to believe, had previously been exempt. This modern introduction of leprosy into virgin soil, so to speak, has taken place in the Sandwich Islands, in New Caledonia, and elsewhere.

Sandwich Islands.— In the case of the Sandwich Islands leprosy was noted among the aborigines for the first time in 1859. After the most painstaking investigation Dr. Hildebrand failed to trace it farther back than 1848. Soon after its presence was recognized the disease spread so rapidly that by the year 1865 there were 230 known lepers in a population of 67,000. By 1891 the native population, from various causes, had diminished to 44,232; of these 1,500 were lepers— about 1 in 30.

New Caledonia.— In New Caledonia leprosy was unknown until 1865. It is supposed to have been introduced about that time by a Chinaman; the man was well known. Its rapid diffusion throughout the island can be, and has been, traced step by step. In 1888 the lepers numbered 4,000. Isle of Pines.— Similarly, in the Isle of Pines leprosy was introduced in 1878, and has since spread. In the Loyalty Islands the first case was seen in 1882; in 1888, in the island of Mare alone, there were 70 lepers.

Symptoms.— Although, as will "afterwards be explained, the Bacillus leprœ is the cause of all leprosy, the clinical manifestations of its presence are far from being identical in every case; indeed, they are almost as varied as are those of syphilis or of tubercle. Our early conceptions of the disease, derived for the most part from the Bible or poetical literature, in which the leper is symbolical of all that is loathsome and hopeless, are apt to mislead. As a matter of fact, in its earlier stages leprosy is far from being always, or even generally, a striking disease. Often for years the only visible evidence of its existence may be two or three small blotches, or perhaps one or two patches of pale or pigmented skin on trunk or limbs— very likely concealed by the clothes and perhaps disregarded by the patient himself— the true significance and nature of which can be appreciated only by the expert. It is generally not until the later stages that we see the disfiguring and extensive lesions on which the popular conception is founded. As a rule, leprosy is a disease of very slow development. Sometimes, it is true, it is suddenly and frankly declared from the outset, and progresses rapidly; but in the vast majority of cases the early lesions are trifling and are apt to be misinterpreted and overlooked, and years elapse before serious mutilation or deformity is produced. The student must bear this important practical fact in mind in the study and diagnosis of all equivocal skin lesions in persons residing in or coming from the endemic haunts of leprosy.

To facilitate description, it seems advisable to divide the evolution of leprosy into stages, premising, however, that the division proposed is in great measure an artificial one. What are here designated stages are not, all of them, clinically and in every instance, abruptly separated or even present; for the most part they merge imperceptibly into each other, and, in not a few instances, some of them cannot be recognized.

1. Primary infection.

2. Period of incubation.

3. Prodromata.

4. Primary exanthem or macular stage.

5. Period of specific deposit.

6. Sequelæ ulceration, paresis, trophic lesions.

7. Terminations.

1. Primary infection.— Seeing that leprosy is caused by a specific germ, there must have been a time, in the history of every leper, when the infecting germ entered the body. In many specific diseases, such as syphilis, the site of the primary infection is indicated by a well-marked local lesion, and the time of infection can usually be ascertained. So far as present knowledge goes, this much cannot be affirmed of leprosy; in this disease we know of nothing that indicates precisely either the seat or, with rare exceptions, the time of primary infection. In this respect leprosy resembles tuberculosis. We are equally ignorant as to the condition of the infecting germ, whether it enters the body as spore or as bacillus, and also as to the medium in or by which it is conveyed. We cannot say whether it enters in food, in water, in air; whether it passes in through the unbroken epithelium, or whether it is inoculated on some accidental breach of surface, or, perhaps, introduced by some insect bite.

Sticker has found Bacillus leprœ in the nasal mucus in 128 out of 153 lepers examined. He considers that the initial lesion of the disease is a specific ulceration of the cartilaginous septum of the nose; the lesion persists and is an active source for the diffusion of infection. Of the presence of this condition, epistaxis, he maintains, is often an early symptom. Several subsequent observers favour this view.

Although we are in absolute ignorance as to the process of infection, we may be quite sure that in leprosy there is an act of infection, and that the infective material comes from another leper. Leprosy has never been shown to arise in a country de novo. There are many facts and arguments to support this statement; their discussion is deferred until the subjects of heredity, contagion, and the hygienic questions connected therewith, come to be considered.

2. The period of incubation.— This is generally, possibly always, long, and has to be reckoned usually in years— two or three at least. There are cases on record in which the period of incubation must have been longer even than this. Danielssen mentions one in which the period was ten years, Leloir describes another in which fourteen years or more, and Höegh one in which twenty-seven years elapsed between the time at which infection was presumed to have occurred and the first manifestations of the disease. On the other hand, cases are on record in which the incubation period was set down at three months or even at a few weeks.

3. Prodromata.— Fever of greater or less intensity and occurring more or less frequently is, almost invariably, a feature of the prodromal stage of leprosy. Febrile attacks may recur off and on during one or two years. It is well to bear in mind that in tropical countries such attacks are apt to be looked on as malarial. Another very common prodromal feature is an unaccountable feeling of weakness, accompanied usually by a sensation of heaviness and a tendency, it may be irresistible, to fall asleep at unusual times. Dyspeptic troubles, associated with diarrhœa in some cases, with constipation in others, and usually attributed to " liver," are also common. Epistaxis and dryness of the nostrils, perhaps symptomatic of the initial lesion, perhaps corresponding to the epistaxis in the prodromal stage of typhoid, tuberculosis, and such as is sometimes met with in early syphilis, are noted by Leloir. Headache; vertigo; perversions of sensation such as localized pruritus, hyperæsthesia, " pins and needles," neuralgic pains— intermittent for the most part, and perhaps very severe and especially common in the limbs and face; general aching, rheumatic-like pains in loins, back, and elsewhere; all or any of these for months may herald the explosion of unequivocal leprosy.

Another curious feature in early leprosy, also noted by Leloir, is the liability in many instances to excessive sweating, which comes on without apparent or on very slight provocation. I had once under observation an Englishman who subsequently developed leprosy, in whom this prodromal symptom was particularly pronounced, so pronounced that he had remarked it himself. This gentleman for many years kept a diary in which, among other things, he recorded very carefully matters relating to his health; so that it was easy to trace from this diary the gradual evolution of his leprosy. The first unequivocal manifestation of the disease, an extensive erythematous patch on the ulnar side of the left arm and hand, which afterwards became anæsthetic, and two or three pigmented spots on the cheek, back, and leg, was noted on March 3rd, 1894. Five years before this there is an entry in his diary, under date June 4th, 1889, of the first of a long series of severe headaches, transient febrile attacks, and progressive deterioration of health and vigour. Under date of June 9th, 1892, is the first mention of the profuse perspiration which, occurring without obvious cause, continued to be a prominent feature until several months after the appearance of the skin lesions referred to. In the diary such entries as the following frequently occur : " Nov. 20th, 1892. Feel poorly and sweating inordinately; wondering what is coming over me. I am very ill." " Dec. 5th to 19th, 1892.— 111 in bed. 1 had furious sweats during this time, and had dreadful pains in the back, the lower part." And again: "Dec. 21st, 22nd. Feeling very ill; awful sweats; weak; done up." As pointed out by Leloir, this hyperidrosis may be general or it may be confined to particular parts, generally the trunk, the limbs being unaffected or even being the subject of anidrosis. A still more limited anidrosis is sometimes noted; it usually happens that these non-sweating Spots become anæsthetic at a later period of the disease. Just as in syphilis, in a very small proportion of cases of leprosy there is a complete absence of constitutional symptoms prior to the appearance of the specific skin eruption.

4. The primary exanthem.— In a considerable proportion of cases, after a longer or shorter period of indifferent health, sometimes preluded by an outburst more severe than usual of fever and other prodromal phenomena, an eruption appears on the skin. This generally coincides with, or is soon followed by, an improvement in the general health.

Although strictly macular, this eruption the primary exanthem of leprosy— varies in different cases as well in respect of the size of the spots as of their number, duration, and other characteristics. They may be no larger than a millet-seed, or they may occupy surfaces many inches in diameter; they may be numerous, or there may be only two or three. The earlier spots are usually purely erythematous, disappearing on pressure, and being darkest in the centre and shading off towards the periphery. But in some cases they may be pigmented from the outset; or they may be mere vitiliginous patches; or all three forms of macula may concur in the same individual— erythematous, pigmented, and vitiliginous. In not a few lepers what in the first instance was an erythematous patch may in time become pigmented, or it may become pale; in the latter case the loss of pigment is usually associated with a certain degree of atrophy of the cutis. Or it may be that the centre of an erythematous patch clears up, the periphery of the patch remaining red and perhaps becoming pigmented; so that the affected spot comes to present the appearance of a red or dark ring, or portion of a ring, enclosing a patch of pale, usually anaæthetic skin. In certain instances the eruption of the various forms of maculæ may be preceded by local paræsthesiæ, such as a sense of burning, tingling, pricking, and so forth.

At first the maculæ may be evanescent and may fade wholly or in part in the course of a few days, weeks, or months; but as the disease progresses, and fresh spots appear, they tend to greater permanency, to be more liable to pigmentation, and are partially or wholly anæsthetic from the outset, or subsequently become so.

A striking feature of this and of all leprous eruptions is the loss of the hair in the affected areas. Another striking circumstance is the fact that the most hairy part of the body, the scalp, is never or very rarely affected either with leprous eruptions or with leprous alopecia. As the face, particularly the superciliary region, is prone to all forms of leprous eruption, falling of the eyebrows is a very usual, very early, and very characteristic phenomenon. The beard, too, is apt to be patchy, particularly in nodular leprosy. In many instances, before they drop out, the individual hairs become white, or downy, or splintered, or monillated.

The most frequent seats of the primary macular eruption are the face, especially the superciliary region, the nose, cheeks, and ears; the extensor surfaces of the limbs; the backs of the hands; the back, buttocks, abdomen, and chest. The palms of the hands and the soles of the feet are rarely if ever attacked. At this stage of the disease the mucous membranes are very rarely affected.

In the distribution of the maculæ a rough symmetry may or may not be discernible.

5. The period of specific deposit.— During the stage just described, if there be any thickening of the skin or other evidence of new growth, it is barely perceptible to sight and but slightly so to touch. Sooner or later, however, another stage is entered on, a stage characterized by the deposit or, rather, growth of a tissue possessing well-marked specific characters. This deposit occurs either in the skin, or in the continuity of the peripheral nerve trunks, or in both. If in the first situation, nodular or, as it is sometimes called, tubercular leprosy is the result; if in the second, we have nerve or anæsthetic leprosy; if in both of these situations, then what is known as " mixed leprosy " is produced. These three forms of the completely developed disease, though having much in common, are, as a rule, clinically fairly distinguishable. It is customary, therefore, to describe them separately.

Nodular Leprosy

This form of leprosy often appears without a well-marked preliminary macular stage, being ushered in, after a longer or shorter prodromal stage, by a smart attack of fever and the rapid development on

Fig. 85.—Nodular leprosy. (After Leloir.)

the face or elsewhere of the specific lesion. In other instances a well-defined but, in comparison with nerve leprosy, short macular stage precedes the appearance of the characteristic lepromata (Fig. 85).

The essential element in nodular leprosy is the leproma. The dimensions, the combinations, the situations, the growth, and the decay of this give rise to the more manifest symptoms of the earlier stages, at all events, of the disease. The leproma, which will be more fully described in the section on the pathological anatomy of leprosy, is formed by infiltration of the deeper layers of the derma with what at first is a small-celled, somewhat dense neoplasm. As this slowly or more rapidly increases it forms a prominent, rounded boss or protuberance covered with unbroken epidermis. In size it ranges from the dimensions of a split pea, or of a bean, to a great plaque many inches across. In colour it differs according to its age and condition, and according to the natural hue of the skin of the leper; it varies from red to dirty pink in the earlier and congestive active stage, to dark brown or dirty yellow in the later stages. It is generally— though not always, especially at first— anæsthetic to some degree, if not absolutely so; it is devoid of hair, usually somewhat greasy-looking and, perhaps, stippled with gaping sebaceous follicles. Though not so hard as cheloid growth, it is fairly firm to the touch, and, unless very extensive, can be readily raised up and freely moved over subjacent structures. Isolated leproinata are usually round or oval; when contiguous they may coalesce, forming patches of irregular outline.

When many lepromata run together, or are closely set, the growth causes the natural folds of the skin to be exaggerated; great disfigurement, especially of the face, may ensue. Thus the skin of the fore head and eyebrows— an early and favourite site of leprous infiltration— is thrown into massive folds and overhangs the eyes; the fleshy parts of the nose broaden out; the cheeks become massive; the lips are thickened and protrude; the chin is swollen and heavy; the external ears are thick and pendulous; and the bloated, dusky, wrinkled, greasy, passive countenance acquires the repulsive appearance very appropriately designated " leontiasis."

Nodules may appear in greater or less profusion on the limbs and body; favourite sites being the backs of the hands, the external surfaces of the arms, wrists, thighs, and the groins. On the trunk they may occupy very large areas, forming extensive plaques. As a rule, in the latter situation they are not so prominent as on the face and arms. The same remark applies to the legs, where the infiltration is usually dusky, diffuse, ill defined, and prone to ulcerate.

From time to time, and at longer or shorter intervals, fresh lepromata appear, their formation generally concurring with an outburst of fever. Occasionally—and this is very often observed during an intercurrent attack of some acute disease, such as an exanthematous fever, or erysipelas, or even of some exhausting disease like phthisis— all or a proportion of the nodules are temporarily absorbed, leaving only slight traces behind. But the normal and usual fate of the nodule is either first to soften in the centre and then to be absorbed, leaving a smooth circular patch of scar tissue; or, after softening, to ulcerate and discharge a sticky, yellowish pus. This discharge tends to dry up into crusts, ulceration proceeding underneath. Finally the ulcer may heal, leaving an irregular, depressed scar.

When the septum of the nose is affected, the cartilage breaks down, the tip of the organ becomes depressed, and a stinking discharge escapes from the nostrils. In such circumstances breathing is very much interfered with, more especially if, at the same time, leprous deposit occurs or ulcerates in or about the glottis, the epiglottis, pharynx, tongue, or mouth generally. The senses of smell and taste are then lost for ever.

The eyes, also, are sooner or later attacked, lepromatous growth spreading from the conjunctiva on to the cornea or into the anterior chamber, or originating in the iris or ciliary body. Ultimately these organs also are destroyed.

Thus, in time, with the exception of that of hearing, one sense after another is lost. Ulcers form everywhere from the breaking-down of the nodules or from injuries to the insensitive skin. The cervical and inguinal glands, owing to leprous infiltration, swell and perhaps suppurate and become fistulous; the abdomen enlarges from leprous, perhaps combined with amyloid, infiltration of the liver, and there may be diarrhœa from amyloid disease of the intestine. In addition to these troubles, if the patient live, the nerve trunks are attacked, and then the neuralgic, paretic, and trophic lesions of nerve leprosy are superadded. The fingers and toes ulcerate and drop off, or they become distorted and atrophied; or the phalanges are absorbed, the hands and feet becoming reduced to useless stumps. A peculiar goat-like smell is emitted by the ulcerating, decaying body. Altogether, the blind, lame, and unhappy wretch— still retaining his intellect, but devoid of every sense except that of hearing, breathing with difficulty through a stenosed larynx, and racked by neuralgic pains and irregular outbursts of fever— comes to present, before the inevitable death from exhaustion occurs, a sadder, more loathsome, and more repulsive picture than anything imagination could conceive. Fortunately, in a large proportion of cases, the leper is mercifully carried off by phthisis, pneumonia, or some intercurrent affection at an earlier period, and before his disease can be said to have run its full course.

NERVE LEPROSY

Just as in nodular leprosy, in nerve leprosy the prodromal and macular stages may be severe, or slight, or altogether absent. Usually, however, in nerve leprosy, much more frequently than in nodular leprosy, the ulterior and more distinctive lesions are preluded by a long and well-marked macular stage, during which large areas of skin are occupied by erythematous (Fig. 86), by pigmented, or by vitiliginous patches. The ringed form of eruption is a very usual one; a red, congested, slightly elevated and, perhaps, hypersesthetic border enclosing a larger or smaller area of pale, anæsthetic, non-sweating integument the whole resembling somewhat one of those extensive body-ringworms so common in natives of hot, damp climates, and for which these rings are sometimes mistaken. Such eruptions may come and go, or they may be permanent, or they may spread and multiply during many years before the more

distinctive and graver signs of nerve leprosy are evolved.

Fig. 86.—Nerve leprosy. (After Lelvir.)

A frequent and very distinctive symptom of. this type of the disease, occurring often about this time, is the sudden appearance of bullee (pemphigus leprosus)—one or more or a series of them— on the hands, feet, knees, backs of thighs, or elsewhere. These bullæ vary in size from a pea to an egg. After a few days they rupture, exposing a reddish surface which

presently crusts over, exfoliates, and finally turns into a pale, perhaps anæsthetic spot with a sharply defined, pigmented border. More rarely the site of the bulla ulcerates. Should similar bullse be formed in the neighbourhood of the first, the resulting ulcerations may unite into an extensive, probably superficial, serpiginous-looking sore.

A time comes when evidence of profound implication of the nervous system, in the shape of severe neuralgic pains, formication, hyperæsthesia, or anæsthesia, becomes more accentuated. The lymphatic glands enlarge, and there is often considerable fever and general distress. Hitherto the most prominent symptoms have been the skin lesions. These may remain or even increase; on the other hand, they may in part or entirely disappear. But whether the skin lesions increase or retrograde, evidences of profound implication of the peripheral nervous system now distinctly show themselves; the neuralgic pains still further increase, and hyperæsthesia, aæesthesia, and various paræsthesiæ, along with trophic changes in skin, muscle, and bone, the results of nerve destruction, become the dominating elements in the case.

If at this stage the ulnar nerve where it passes round the internal condyle of the humerus be examined, generally it will be found to be the seat of a fusiform swelling, perhaps as thick as the little finger. Other nerves, such as the anterior tibial, the peroneal, more rarely the median, radial, brachial, and cervical nerves, especially where they pass over a bone and lie close under the skin, can be felt to be similarly swollen. Occasionally even the smaller nerves, where superficial, can also be detected hard and cord-like. At first these thickened nerves are tender on pressure, and the parts they supply may be the seats of hyperæsthesia and acute neuralgia. By degrees the great thickening of the nerve trunks decreases somewhat, the hyperæsthesia and neuralgia subside, and anæsthesia, paresis, muscular atrophy, and other trophic changes take their place. For a time the condition may fluctuate; the neuritis apparently may come and go with corresponding changes in the condition of the area subserved by the affected nerves. Sooner or later, however, fibrotic changes ensue in the neural leprous deposits, and the nerve tubules ultimately atrophy and disappear. The nerve tissue is now irreparably damaged, and trophic changes steadily advance. In other instances anæsthesia comes on without neuralgic pains, without hyperæsthesia, without constitutional symptoms, without discoloration of the skin, the patient discovering its existence by accident.

In nerve leprosy the anæsthesia begins most commonly in the feet, the thighs, hands, arms, forearms, and face. Later, and more rarely, it affects the trunk. The anæsthesia, though associated with well-marked lesions of the larger nerves, does not always, or even as a rule, coincide accurately with the anatomical distribution of their terminals; a circumstance which tends to show that the anæsthesia is not always and simply the result of lesion of nerve trunks, but that it may be the effect of the destruction by the bacillus of the nerve terminals themselves. This suggestion is strengthened by Gerlach's discovery that in anæsthetic leprosy the bacilli appear first in the skin around the nerve terminals, and only subsequently extend upwards to the nerve trunks. Another and sometimes a very striking fact in nerve leprosy is the symmetry observed in the distribution of some of the anæsthetic areas. This symmetry is by no means invariable; in not a few cases, however, it is very perfect and remarkable.

At the outset the anæsthesia in the affected patches may not be absolute; it may also come and go; and it may be very superficial, deep pressure being for a long time appreciable. But when the anæsthesia becomes, as it were, settled in a part, it seems gradually to extend deeper into the tissues; so that after a time it is absolute, and the part may be pinched, incised, and even seared with fire, and the leper be absolutely unconscious of pain or even of being touched.

Step by step with the progress of the anæsthesia, atrophy of the subjacent muscles supplied by the thickened nerves proceeds. Along with the atrophy there is a corresponding distortion and a corresponding loss of power. There is no ataxia or incoordination of movement simply feebleness. Thus the forearm wastes, the grasp is weakened, the thenar and hypothenar eminences and the interossei melt

Fig. 87.—Nerve leprosy: main-en-griffe. (After Leloir.)

away, and the main-en-griffe or some such deformity is gradually produced (Fig. 87). Similar changes occur in the legs and feet, so that the power of walking is much impaired. The muscles of the thighs and upper arms, the pectorals, and the muscles of the face follow suit very much as in progressive muscular atrophy, only in the latter disease there is no superjacent anæsthesia.

In the affected nerve areas all the muscles are not simultaneously or equally attacked, so that, especially in the face, curious distortions may ensue. These facial atrophies, whether symmetrical or one-sided, in time produce a facies as characteristic of nerve leprosy as leontiasis is of nodular leprosy. Owing to muscular atrophy, the eyes, after a time, cannot be closed; the upper lid droops, the lower lid becomes everted, and the eye itself may become fixed. At first, owing to exposure of the organ, there is lacrimation; but by and by the secretion of tears dries up, the congested conjunctiva becomes cornified, the cornea ulcerates or turns leucomatous, and in the end sight is entirely lost. Ulceration often occurs in the mucous membrane of the nose, the septum being destroyed as in the nodular form; the tip of the nose may then fall down or be entirely lost. The lips, too, may become paralysed, thereby interfering with articulation and permitting the saliva to dribble from the mouth in a constant stream. Changes occur, also, in the mucous membrane of the mouth; the gums may retract, exposing the maxillary bone, the teeth ultimately dropping out. Anæsthesia of the tongue and buccal mucous membrane, and implication of the muscles of mastication, may render eating and articulation very difficult.

In time the skin of anæsthetic patches on the limbs tends to atrophy; it loses its glands and hairs, and, in the end, may become so thinned and tense that it actually bursts into long cracks. The nails are not generally shed, but they become rough, or thinned, or atrophied into minute, hook -like appendages. Ulcers form over exposed parts of the hands and feet. They may penetrate and disorganize the joints, and thus often cause fingers and toes to drop off, one after another. Or, perhaps, an abscess forms around a phalanx, destroys the periosteum, and ultimately leads to loss of the bone. Or a sort of dry gangrene may amputate finger or toe. Or there may be a curious interstitial absorption of one or more phalanges, the shaft of the phalanx wasting more rapidly than the articulating surfaces. In any of these ways the fingers and toes are distorted or destroyed. It is no unusual thing to see on a leper's hand a finger in which one or more of the phalanges have been thus got rid of without destruction of the fieshy part, or with only a general shrinking of this. Thus it comes about that a distorted, talon -like nail may crown a finger which is a mere stump; or, the finger having been entirely absorbed, the nail springs, as it were, directly from the knuckle.

Perforating ulcer of the sole of the foot, usually under the ball of the great toe or the heel, is a very common lesion in nerve leprosy.

On the whole, the advance of this form of leprosy is much slower than that of the nodular variety. The average duration of the latter is from eight to nine years, of nerve leprosy about eighteen years. Often such lepers live much longer— twenty, thirty, or even forty years. The end of these cases is quite as sad and repulsive as that of nodular leprosy. Death seldom results directly from the disease itself, but usually from diarrhœa, chronic nephritis, phthisis, pneumonia, or bronchitis.

MIXED LEPROSY

As already explained, in most cases of nodular leprosy trophic changes from implication of nerve trunks ultimately supervene. Similarly, though not so frequently, nodular infiltration of the skin may appear in the course of what originally seemed to be a case of pure nerve leprosy. In yet other cases nodular and nerve lesions concur from the outset. In one or other of these ways what is known as mixed leprosy is produced. The lesions are in no way different from those already mentioned, and therefore this form of the disease does not call for more detailed description.

Pathological anatomy. Bacillus leprœ.— The lesions of leprosy are the result, direct or indirect, of the proliferation of the Bacillus leprœ in the tissues. This parasite (Fig. 88) in size, shape, and staining reactions closely resembles the bacillus of tubercle. In length it is from half to two-thirds, and in breadth about one-sixteenth the diameter, of a blood corpuscle. The ends of the rod— which is always straight— are in many specimens somewhat attenuated; and in many instances— presumably in old bacilli— a moniliform arrangement of the protoplasm, as if from spore formation or, according to Hansen, from disintegration, can be detected. By some authorities it is said to possess a gelatinous capsule. In common with Bacillus tuberculosis and Bacillus smegmæ it retains carbol-fuchsin stains after being treated with mineral acids. It may be distinguished from Bacillus tuberculosis by its staining more readily with cold weak solution of carbol fuchsin, and by being decolorized more easily with dilute acids; by the impossibility hitherto experienced of growing it on the usual culture media, and of successfully in-

Fig. 88.—Bacillus lepræ. x 1,000. (Muir and Ritchie.)

oculating it into man and the lower animals; by its tendency to occur in dense clusters and in greater numbers; and by its very generally being found inside cells or, according to Unna, in zooglœa masses in the lymphatic spaces.

Specimens of the bacillus can be procured readily by excising a portion of a leproma—a proceeding, in consequence of the absence of sensation in most tubercles, not usually much objected to by lepers; or they may be obtained by including a succulent leproma in a pile clamp, slowly screwing up the jaws of the instrument so as to drive out the blood, ing the now pallid leproma, and then collecting on a cover-glass the droplet of " leper juice " which exudes from the puncture. The juice may be spread out on the cover-glass, fixed, stained, and decolorized as for the demonstration of tubercle bacilli; or it may be examined fresh. Better preparations are obtained by making with a small scalpel a minute incision into the compressed leproma, scraping some of the tissues from the under surface of the skin, and smearing this with the juice on to the cover-glass. One must be careful to exclude the possibility of contamination with Bacillus tuberculosis, with which lepers are often infected.

If examined fresh, or if a morsel of leproma be teased up in water, the bacilli may be seen both inside and outside the cells and in active motion. Whether this motion is simply molecular, or whether it is vital, is hard to say; probably the former, for, whilst osmic acid does not stop it, it is immediately arrested by the addition of a viscid fluid, such as glycerin or albumin water.

The bacillus is found in all primary leprous deposits; in the skin leproma— where it occurs in prodigious numbers; in the meagre infiltration of the macular eruptions— where it is much more sparsely distributed; in the early stage of leprous neuritis— where, also, it is present only in small numbers; in the specific lesions of the liver, spleen, testes, lymphatic glands, and lungs— where the lesions may resemble those of tuberculosis or may be invisible to the naked eye. In the blood-vessels it has been found in the endothelium and, occasionally, free in the blood or enclosed in leucocytes. It is abundant in the purulent discharges from the nose, from ulcerating lepromata or other forms of primary leprous infiltration. It has very rarely been found in the spinal cord or in the lungs. It is doubtful if it occurs in the brain, the intestinal tract, or in the kidneys, although the latter are prone to inflammation in leprosy. It is not found in muscle, in bone, or in cartilage ; and it is not necessarily present in the secondary trophic lesions of nerve leprosy, or in secondary inflammatory effusions. Many apparently unsuccessful attempts have been made to cultivate the lepra bacillus. I use the word " apparently " because some modern leprologists consider that probably a proportion of these attempts were successful, although at the time not regarded as being so. Mycotic forms developed in the culture media, but as these forms were not acid-fast they were regarded, at the time, as contaminations and not growths of the lepra bacillus.*^[1] A modern view is to the effect that Bacillus leprœ is really a streptothrix like the actinomyces, or, according to^some, the tubercle bacillus, that it is pleomorphic to a high degree, and that at a certain stage of growth and under certain conditions the mycelia break up into short rods, many of which are now acid-fast. There is great discrepancy of opinion among bacteriologists on the subject, each observer having his special lepra germ grown on his special culture medium; this germ he regards as the only true one, conforming, he claims, to the proper agglutination and complement-fixation tests, and its products possessing a therapeutic value comparable to that of tuberculin, and giving rise to a local and a general reaction when injected into lepers. Other bacteriologists, though following the methods that have succeeded in the hands of their authors, have generally failed to obtain similar results.

The discovery that rats (5 per cent, in Paris) are subject to a disease clinically resembling human leprosy may lead to a better knowledge of the lepra bacillus, seeing that the lesions of the "rat leprosy," as it is called, are intimately associated with an acid- fast bacillus resembling that of human leprosy, and that it is communicable to other rats by association.

The leproma.— The young leproma presents a smooth, white, glistening section. When the leproma is older the cut surface has a brown tint, and the morbid tissue may become, from fibrotic changes, harder, or, from degeneration, softer. The specific lesion of leprosy differs from that of tubercle inasmuch as the former is well supplied with blood-vessels, contains no true giant cells, and never undergoes caseation. If hardened, cut, stained, decolorized, and examined under the microscope, the leproma is found to consist principally of small round cells about the size of a leucocyte, epithelioid cells, and fusiform cells the two latter in numbers increasing with the age of the leproma. It can be seen that these cells have infiltrated and partially dissociated all but the most superficial layer of the derma. It may be further observed that the cells are arranged for the most part in groups, generally around and near blood-vessels; and that a very large proportion of them contain bacilli, some cells having only a few, whilst others are literally crammed with the organisms. Isolated bacilli are also found scattered through the preparation, apparently free in the lymph spaces. The bacilli are never seen inside the nuclei of the implicated cells.

In addition to the bacilli-bearing cells, and increasing in number with the age of the lesion, a number of brown granular bodies, larger and smaller, which have been named " globi," are to be found. These Hansen holds to be cells in which the bacilli have perished and become granular. It is to them that the brown colour of old lepromata is due.

There has been considerable discussion as to the exact position of the bacilli as regards the lepra cells —whether they lie inside the cells or whether they are free. On the one hand, Unna holds that they lie free in the lymph spaces, and that they are never in the cells, the appearance of cell inclusion being produced by the zooglœa arrangement so common with bacteria. On the other hand, Leloir maintains that some of the bacilli are free whilst others are inside the cells. A third set of observers, following Hansen, hold that the bacilli are almost invariably included within cells, the nuclei of which can readily be demonstrated surrounded by the parasites.

Other lesions.— The histology of the infiltrated macula is practically the same as that of the leproma, the number of bacilli, lepra ceils, and globi being proportionately fewer. In old , maculæ, as in very old lepromata, the bacilli may be hard to find or entirely absent. In the anæsthetic maculæ the terminal nerve fibres are degenerated.

As the fusiform thickening of the larger nerve trunks in nerve leprosy is a secondary inflammation, bacilli may not always be found in it, although at the very commencement of the nerve disease bacilli, both in cells and, according to Leloir, free between the nerve tubules, are present and may even lie in the nerve tubules themselves. In time the affected nerves become mere fibrous cords destitute of nerve tubules.

The anatomy and histology of the various trophic lesions are such as are found in other examples of destructive neuritis, and are in no way peculiar to leprosy; they do not, therefore, call for description here.

In nodular leprosy the liver and spleen are the seat, in many instances, of a peculiar infiltration which, in well-marked examples, may be visible to the naked eye. Fine yellowish-white dots and streaks are seen to occur in the acini of the former. These dots and streaks consist of new growth in which bacilli abound. According to Leloir, the parasites are never found in the hepatic cells themselves.

In all cases of nodular leprosy the testes atrophy and undergo fibrotic changes, bacilli and globi being found both in and around the tubules, free and in cells.

In all forms of leprosy the lymphatic glands appertaining to parts in which leprous deposit is present are characteristically affected. They are swollen and hard, and on section the gland tissue is seen to have a yellowish tinge from an infiltration which contains numerous bacilli and globi.

Albuminoid disease of the alimentary canal, liver, and spleen, and nephritis occur in a large proportion of the cases of nodular leprosy.

Diagnosis.— The touchstone in all doubtful cases is the presence or absence of anæsthesia in some skin lesion, or in some skin area. Anæsthesia is rarely absent in leprosy; generally, in the implicated spots it is complete, or nearly so. It should be particularly sought for towards the centre of maculæ, in the pale patches left after the fading of former maculæ, in the hands and feet, and in nodules of some standing. In no other skin disease is definite anæsthesia a symptom.

Vitiligo or leucodermia— sometimes called white leprosy, and by the vulgar very generally regarded as true leprosy— bears a certain resemblance to the pale post-macular patches referred to; not to mention other features, the absence of anæsthesia in leucodermia at once settles diagnosis.

Further assistance may sometimes be got in doubtful cases from the fact that leprous spots rarely perspire. A hypodermic injection of pilocarpine is of use in bringing out this point.

The sensory and trophic lesions of syringomyelia might be mistaken for nerve leprosy, but the general history of the case, the history or presence in leprosy of macular eruption, of thickened nerve trunks, and of enlarged lymphatic glands, and their absence in syringomyelia, are mostly sufficient to establish a diagnosis.

The occurrence of an acid-fast bacillus in the sputum of a patient coming from a country in which leprosy is common should be regarded with suspicion, and its true nature tested by injection of the sputum into the guineapig. "

It is hardly necessary to point out the diagnostic marks of leprosy as against syphilis,*^[2] erythema multiforme, erythema nodosum, trypanosomiasis, lupus vulgaris, lupus erythematosus, psoriasis, eczema, lichen planus, cheloid, body-ringworm, erythrasma, pityriasis versicolor, pellagra, elephantiasis arabum, etc. Mistakes can scarcely be made unless from carelessness, or by someone completely ignorant of the nature, history, and symptoms of these diseases.

In approaching the diagnosis of skin eruptions, localized pareses, muscular atrophies, and anæsthesia in patients living in or coming from a country in which leprosy is endemic, the possibility of their being attributable to this disease must be borne in mind. If doubt exist, and it be found feasible, search for the bacillus should be made in eruptions, or in thickened nerves, or in any nasal or other morbid discharge that may be present. If this be found the diagnosis of leprosy will be infallibly established.

Prognosis.— Complete recovery is an event so rare in leprosy that, though it may be hoped for, it must not be expected. Recovery from the actual disease itself— that is, in the sense that fresh leprous infiltration may cease to occur, and old infiltration may be absorbed, and that the bacilli may die out— is perhaps the rule in nerve leprosy; but the effects of the leprous process are generally permanent, the trophic lesions resulting from nerve destruction being irremediable. Such cases may live, however, for many years— thirty or forty— and die of some other disease.

Nodular leprosy is usually a much more acute disease than nerve leprosy, sapping the strength and general health much more effectually and more quickly. It rarely runs its full course, death being brought about by some intercurrent disease, such as, and especially, phthisis, nephritis, albuminoid degeneration of the alimentary tract, dysentery, stenosis of the larynx, or pneumonia. It may even prove fatal as a sort of "galloping" leprosy within a year of its first declaring itself.

Etiology. Age.— It is open to question if leprosy has ever been seen in the foetus. It has once or twice been reported in the newly born. Cases are also on record of its occurrence as early as the first and second years of life; such cases, however, are quite exceptional. Leprosy is extremely rare before the fifth or sixth year. In the great majority of instances the disease begins between the tenth and thirtieth year. It rarely commences after 40, although it has been known to begin up to and even after 70.

Sex; occupation; social and hygienic conditions. —Apart from social conditions as affording opportunity for contagion, sex seems to have little bearing on the liability to leprosy. The same may be said of occupation, and social and hygienic conditions in general. Very probably bad food and bad hygienic circumstances have in this, as in most germ diseases, a predisposing influence but they certainly cannot create a lepra bacillus and leprosy, any more than they can create an acarus and itch. This is abundantly, shown by the absence of leprosy at an earlier period in countries in which, without alteration in the food or other hygienic conditions, the susceptibility of the natives to the disease was subsequently proved by its rapid spread on being introduced from without, e.g. the Sandwich Islands and New Caledonia; and also by the disappearance of the disease, in other instances, under the influence of the segregation and isolation of lepers, without any concurrent material alteration in food or other circumstances, e.g. Scotland, Ireland, and most European countries.

Sir Jonathan Hutchinson very sagaciously and truly remarked that leprosy is more especially a disease of semi-civilization. Savages are exempt; the highly civilized are exempt; but when the savage begins to wear clothes and live in houses he becomes subject to the disease. In other words, in the early stages of civilization opportunities of infection are multiplied, and their influence is not counteracted by cleanliness of house or person.

Climate.— Climate can in no way be considered a cause of leprosy, for leprosy exists in all climates and in all latitudes. But it does seem to have some influence in determining, to a certain extent, the type the disease assumes. It would appear that the nodular form is more common in cold, damp climates; the nerve form in warm or dry climates.

The lepra bacillus.— Hansen remarks, "There is hardly anything on earth, or between it and heaven, which has not been regarded as the cause of leprosy." However true this remark may be as regards times prior to Hansen's discovery, we are now practically certain that the lepra bacillus is the cause of leprosy. The only gap in the evidence, otherwise conclusive, lies in our present inability to convey with certainty, by inoculation or otherwise, the cultivated bacillus to the lower animals, or, perhaps, to man himself.

Many attempts have been made to communicate leprosy to man by inoculation; hitherto, with one questionable exception, all have failed. A Sandwich Islander, apparently at the time free from leprosy, was inoculated from a lepra nodule. Within a month he had symptoms of leprous neuritis; two years later he was a confirmed leper; and in six years from the date of the inoculation he died of leprosy. Unfortunately the subject of the experiment was a native of a country in which leprosy was extensively endemic, and, besides, he had lived among lepers; in fact, members of his family were lepers. However possible it may be that the bacillus in this instance had been communicated by the inoculation, the circumstances in which the experiment was made, and the unusual shortness of the incubation period, are against its being regarded as conclusive evidence of the inoculability of the disease.

To bridge over this important gap in the evidence, we have to fall back on the close analogy that subsists between Bacillus lepræ and Bacillus tuberculosis, the leproma and the tubercle, leprosy and tuberculosis. In consideration of this and other circumstances, it is generally conceded that Bacillus lepræ, is the cause of leprosy, just as Bacillus tuberculosis is the cause of tubercle. Authorities differ, however, as to the way in which the bacillus is acquired.

How acquired.—It is absurd to suppose that an organism, no matter how humble its place in the scale of life, can originate de novo. Disregarding this, we have to consider two principal views as to the way in which the bacillus is acquired—heredity and contagion.

Heredity.—From the fact that it tends to run in families^[3] and that in certain instances it assumes the appearance of atavism, leprosy, until the Bacillus lepræ was discovered, was almost universally—as it still is by some—believed to be an hereditary disease. That this belief, in the same sense as that tubercle may be said to be hereditary, was well founded is quite possible; that is to say, that certain physio-pathological qualities predisposing to leprosy may be inherited. But since the discovery of the bacillus it is impossible any longer, if we properly consider it, to believe that the bacillus itself, and therefore the disease it causes, can be hereditary in the scientific sense of the word. Physiological peculiarities and susceptibilities may, but parasites cannot, be inherited. It is true the ovum may be infected by a germ, as in syphilis; but infection is not heredity. That the ovum can be infected at some stage of its existence by the lepra bacillus is proved if it be true that children have been born with the lesions of leprosy on them. But the fact that leprosy is common in the descendants and blood collaterals of lepers is no proof of ovum infection in every, or perhaps in any case; for family liability is quite as explicable by an hypothesis of contagion, or outside infection, as by an hypothesis of inherited infection. Not only may the individuals of a family inherit a family predisposition of susceptibility to the bacillus, but, as a family, the members of it are generally at one time or another closely associated, exposed to the same hygienic influences, liable by contact to communicate each other's parasites, or to acquire the parasites latent in their common surroundings. Because the members of a family simultaneously, or one after another, contract scabies, or ringworm, or typhoid, no one supposes on that account that any of these diseases is hereditary.

Without absolutely denying the possibility of ovum infection, the probability is that such an event is very rare. The age at which leprosy usually appears is against such a supposition. The latency of a germ for twenty, thirty, forty, or even seventy years is an extremely improbable thing and without parallel in pathology. Atavism, or rather, the appearance of atavism, frequently met with in leprosy, is also against such a supposition; for, although we can understand infection of an ovum by a leper parent, we cannot understand the transmission of a germ from a grandparent to a grandchild through a parent who is not, never was, and may never become a leper. Such a thing would imply proliferation of the bacillus in the parent without pathological evidence of its presence.

Even admitting that leprosy is sometimes transmitted by ovum infection, this method of transmission cannot be the only one, or even a common one, for many lepers have no leper ancestors; and, as is well known, the healthy European, coming from a country in which leprosy has not been seen for generations, may acquire leprosy on visiting a country in which the disease is endemic.

If leprosy be communicated generally, or even sometimes, by parent to child by heredity, how explain the striking fact, brought out by Hansen, that of the numerous offspring of 160 Norwegian lepers who emigrated to America not one has become a leper?—or, again, the equally well attested fact that children sometimes become lepers first, their parents afterwards?

Another powerful argument against the doctrine of heredity is the circumstance that lepers become sterile early in the disease. From this it is evident that unless the ranks of leprosy are recruited in some other way than by heredity the disease would inevitably die out in one or, at most, two generations.

From considerations such as these the view that leprosy is an hereditary disease has now few adherents among the well informed.

Contagion.—With few exceptions, the best authorities believe that leprosy is propagated by contagion, and only by contagion. The same unanimity of opinion does not obtain as to the particular way in which, or medium by which, the contagium is applied; but that it passes, directly or indirectly, from the infecting leper to the infected, nearly all are agreed to regard as being practically proved. The principal facts and considerations on which this important conclusion is founded are as follows:—

Leprosy is a germ disease, and therefore it cannot originate de novo. It must come from a pre-existing germ whose habitat may be air, soil, water, plant, beast, food, or man. That the habitat of the infecting germ is man is rendered in the highest degree probable by the fact that the germ is found in the human tissues and, hitherto, nowhere else; and by the fact that leprosy has never been known to appear on virgin soil independently of the prior advent of a leper. When a leper settles down in virgin country, after a time cases of the disease crop up among his companions and immediate neighbours. Some of these newly-made lepers, proceeding to a different part of the country, in time become centres for other groups of cases. Thus in the early history of the introduction of leprosy into a virgin country—as New Caledonia—the spread of the disease from individual to individual, and from place to place, can be, and has been, traced.

In further proof it can be advanced that not only may a native of a non-leper country acquire the disease on visiting a leper country, but he may also communicate the disease to others, his countrymen, on his return to his own country. There is at least one well-authenticated example of this on record. Dr. Hawtrey Benson, in 1872, showed at the Medical Society of Dublin a leper, an Irishman, who had acquired his disease in the West Indies. After his return to Ireland he slept in the same bed as his brother, who, moreover, sometimes wore the leper's clothes. In time the brother, who had never been out of the United Kingdom, became a leper, and was shown to the same medical society in 1877. In this case there can be no question of fact or of diagnosis. Such a case can only be explained by contagion. Though not quite so well authenticated and conclusive, many similar instances of the communication of leprosy by contagion are on record. The case just mentioned is alone almost conclusive; for if leprosy is proved to be communicable by contagion in one case, the probabilities are that it is so acquired in every case.

It has been advanced against the contagiousness of leprosy, that it attacks a very small proportion only of the attendants, nurses, and doctors in leper asylums. But might not a similar objection be raised to the contagiousness of scabies or of ringworm? The conditions for successful contagion are known and can be easily avoided in the latter diseases; they are not known, and are therefore not invariably avoided in leprosy. All contagious diseases demand certain conditions for their diffusion. In some diseases these conditions are easily complied with and often concur; in other diseases they are with difficulty complied with and rarely concur. Leprosy belongs to the latter category.

Probably intimate personal contact, and certain concurrences in the -phases of the disease with special conditions in the health or physiological state of the recipient, are necessary for the successful communication and acquisition of leprosy. The simple implantation of the bacillus does not suffice; for, as already pointed out, of the many inoculations that have been made only one has any claim to be regarded as having been successful. Articles of diet, such as imperfectly cured fish, have been incriminated as media for infection. Sir Jonathan Hutchinson for many years strenuously advocated this doctrine. The historical, epidemiological, and circumstantial evidence on which it is sought to establish this speculation, though highly suggestive, is, in the opinion of most authorities, insufficient.

Prevention.— If it be conceded that leprosy is caused by a germ, that it is contagious directly or indirectly, and that it never breaks fresh ground unless first introduced from without and by a leper, then the leper must be regarded as a source of danger, and, qua leprosy, the only source of danger to any community he "may live amongst. Therefore a sure and the most effectual way of suppressing the disease is the thorough isolation of existing lepers. There are many difficulties, however, especially in such countries as India, in giving practical expression to what appears to be a perfectly logical conclusion difficulties springing from the rights of the individual, finance difficulties, difficulties arising from concealment or incorrect diagnosis, as well as from the continued introduction of fresh cases from without. These and other obvious obstacles, incident to any attempt at a wholesale system of thorough isolation, are so great that the most that can be hoped for at the present time, and in the present state of public opinion, is some modified system of segregation and isolation, such as has worked so successfully in recent years in Norway.

Where possible, therefore, lepers should be segregated in isolated asylums, which should be so conducted as to prove attractive. Those who cannot be made, or persuaded, to enter these asylums should be isolated as much as possible from their families and the public; scrupulous cleanliness of their persons and houses should also be insisted on. Lepers ought not to be allowed to beg in the streets as is often the case in Eastern cities to keep shops, or to handle food or clothes intended for sale, to wander about the country as pedlars or mendicants, to hire themselves out as servants or prostitutes, or to frequent fairs and public places. All lepers in the ulcerative stage of the disease, when it is to be presumed that myriads of bacilli are being constantly given off from their sores, should be still more scrupulously isolated, their discharges, clothes, and dressings being systematically destroyed or disinfected. A child born of a leper should at once be removed from the diseased parent, and, if necessary, cared for at the public expense.

Leprosy is feebly contagious, or rather, the conditions for successful contagion rarely occur; so rarely, that it is more than probable that under such a modified system of segregation and isolation as that indicated they would occur so seldom that the disease would rapidly die out.

Vaccination.— It has riot been actually proved that leprosy can be communicated by vaccination, although there is some evidence in favour of such a supposition. But, although this has not been proved, it is an obvious and very desirable precaution, in countries in which the disease is endemic, to take care that the vaccinifer is not only not the subject of actual leprous eruption, but also that he or she comes from a family and community free from leprosy. An apparently healthy vaccinifer may contain lepra bacilli in a latent state— may be, in fact, a potential leper and capable of communicating the disease.

Treatment.— Scrupulous and systematic attention to personal and domestic hygiene and cleanliness; frequent bathing and the free use of soap; frequent changes of underclothing; good food; fresh air; light work; the avoidance of overstrain, fatigue, and of exposure to bad weather— these things are all of prime importance in the treatment of leprosy, and should be insisted on. It has been found that most lepers on being placed in favourable hygienic conditions improve for a time, and that in a small proportion of cases the disease by these means may sometimes be actually arrested. Europeans who have contracted leprosy in the tropics almost invariably undergo temporary improvement on return to the more bracing climate and more nutritious diet of their native lands. It seems to me that the methods of treatment now coming into vogue for tuberculosis are equally applicable to leprosy.

Many drugs have been regarded, from time to time, as being more or less in the nature of specifics in the treatment of this disease. But, though some of these drugs appear for a time to do good, and in consequence acquire a certain degree of popularity, hitherto all of them, one after another, have sooner or later fallen into disfavour. One is very apt to be deceived in estimating the value of a drug in leprosy. The leper applies for treatment generally during, or soon after, one of the periodical exacerbations of the disease, and when the nodules and other eruptions are active and well pronounced In the natural course of events, and without treatment of any description, especially if the patient be placed under favourable hygienic conditions, these acute manifestations tend to become quiescent, and the disease temporarily to ameliorate. Observers are too apt to attribute this natural and temporary amelioration to whatever drug the patient may happen to be given at the time. Moreover, in judging of the value of any drug in leprosy, it must be remembered that the disease may be arrested spontaneously, or even be recovered from, without the use of any drug whatever.

Chaulmoogra oil (Oleum gynocardium), in doses of from 2 to 10 up to 40 drops or more, according to tolerance, three times a day, together with inunction of the same drug mixed with some oil, is a favourite remedy with English practitioners. Such lepers as can assimilate large doses of this drug appear to derive benefit. Sandwith has reported a case in which marked benefit followed persistent hypodermic administration of chaulmoogra. I have had lepers under my care who, in addition to large doses of chaulmoogra by the mouth, received hypodermic injections daily up to one drachm of the drug. The improvement for a time was marked. The bacilli, however, were just as abundant in the nodules during and after as before treatment, and there was no alteration in their appearance. Encouraged by the clinical results, I have persevered with this treatment for many weeks at a time. In one instance the patient died from what was suspiciously like fat embolism; in another, while very large doses of chaulmoogra were being taken by the mouth and injected hypodermically, severe leprotic fever, associated with profuse eruption of lepromata, set in.

Sir Leonard Rogers has obtained very encouraging results from the intravenous injection of sodium gynocardate *^[4] in doses of 1/10 to 4/5 gr. in 3-per-cent. sterilized solution. A definite local reaction in a proportion of cases, sometimes with fever, follows the injection.

Anti-leprol (Bayer), a preparation derived from chaulmoogra oil, is better tolerated than the crude drug and may be given in larger doses, up to 2 or 3 drachms a day by mouth and 7 minims subcutaneously twice a day.

Rocamora reports favourably of combining a prolonged (eighteen months) salvarsan treatment with a chaulmoogra course.

Gurjun oil, once in favour, seems to have been abandoned.

Unna claims to have cured several cases of leprosy by the internal administration of ichthyol in increasing doses, combining the internal medication with vigorous rubbing of the arms and legs twice a day with pyrogallic acid (10 per cent.) in lanolin, and the cheeks and trunk with chrysophanic acid (10 per cent. ) in lanolin; at the same time applying to the forehead and chin a plaster of chrysophanic and salicylic acids with creosote, changing the plaster every day. The treatment is continued for a month, and is then followed by a course of warm baths before being resumed.

Tuberculin has also been tried. It produces a local and a general reaction, which is sometimes curiously delayed for one or two days. So far from doing good it seems to aggravate the disease, causing fresh eruptions, and also causing bacilli to appear in the blood.

Radcliffe Crocker recorded several cases of leprosy in which great improvement followed weekly hypodermic injections of 1/5 gr. of perchloride of mercury.

Iodide of potassium aggravates leprosy if given in full doses; it not only affects the general health prejudicially, but it causes fresh eruptions to appear.

Danielssen regards salicylate of soda, combined with cod-liver oil, quinine and iron, good food, and good hygiene, as the best treatment for leprosy. He claims for the salicylate, if commenced within the first few months from the appearance of the disease, that it sometimes effects a cure. He begins with 15 gr. four times a day, and gradually increases the dose during six months or a year.

I have tried thyroidin in a case of nerve leprosy. The patient is now absolutely free from symptoms.

Salvarsan administered at frequent intervals intravenously and combined with anti-leprol is said to have given favourable results in nodular but not in anæsthetic cases.

Hydroxylamin, europhen, naphthol, salol, methylene blue, and aristol have also been tried recently; the results have not proved encouraging.

It has been proposed to treat leprosy by inoculations of the erysipelas streptococcus, or by injections of the filtered toxin obtained from cultures of that organism (Impey).

Nerve-stretching, with or without nerve-splitting, has been strongly advocated (McLeod) for the cure of leprous neuralgia, anæsthesia, muscular atrophy, and other trophic lesions. At the best they can benefit the local lesion alone, and that but temporarily, and only in the earlier stages of the leprous neuritis before the nerve has undergone fibrous transformation.

In the case of leprous nodules spreading on to the cornea and threatening to interfere with the line of vision, Brockmann has shown that the extension of the leproma may be arrested by division of the cornea on the pupillary side of the lesion; it is found that the bacilli do not traverse the cicatrix. Tarsorrhaphy for ectropion of the lower lid; iridectomy for iritis, or synechiæ; tracheotomy for laryngeal stenosis; and necrotomy for bone disease, may sometimes have to be performed. Horder strongly recommends amputation for perforating or other forms of ulceration; the general health is much improved by the removal of such sources of sepsis. The existence of leprosy does not materially interfere with the success of surgical operations. I once removed an enormous elephantiasis of the scrotum from a confirmed leper; the presence of the leprosy did not prevent sound healing of the extensive operation wound, the man making a good recovery so far as the operation was concerned.

If only one tubercle or one limited lepra macula is present, and there have been no constitutional signs of a general invasion, it is advisable to excise freely the affected spot.

What promised at one time to prove an important advance in the therapeutics of leprosy is the method introduced by Prof. Deycke under the name of nastin treatment.

Prof. Deycke obtained from a case of nodular leprosy a peculiar acid-fast bacterium— Streptothrix leproides— resembling in many respects Bacillus leprce, but differing from the latter inasmuch as it could be readily cultivated. In unskimmed milk it forms a brilliant orange-red pellicle, which on digestion with ether yields a fatty substance— "nastin"— of definite chemical character. Injections of pure nastin in oily solution give rise in some lepers to inflammatory reaction of varying degrees of intensity— it may be violent; in other lepers again no such reaction occurs. Concurrently with reaction there is pronounced bacteriolysis and disappearance of the lepra bacilli as evidenced by their losing their staining reactions and by their disintegration. Several patients treated in this way improved, some apparently recovering; but the uncertainty as to whether in any given case reaction might not prove of so violent a character as to be dangerous to life imposed limitations upon the general use of the remedy.

Finding that benzoyl-chloride (${\ce {C6H5}}$.${\ce {CO}}$.${\ce {Cl}}$), by removing their fatty protective contents, rapidly deprived tubercle bacilli of their "acid-fastness," he concluded that this substance might act similarly on the lepra bacillus; and also finding that benzoyl-chloride was innocuous, he concluded that by combining it with nastin the therapeutic efficiency of the latter might be so reinforced that it could be used in doses so small that violent reaction would be avoided. Experiment justified the conjecture, and although benzoyl-chloride administered alone has no therapeutic action in leprosy, given in appropriate combination with nastin, in a large proportion of instances, although not in all, the results are highly satisfactory, the lepra bacilli and lepra lesions slowly or more rapidly disappearing.

Prof. Deycke's hypothesis as to the mode of action of the combination is to the effect that the nastin element, having affinities with the fat of the lepra bacillus, acts merely as the introducer of the benzoyl-chloride, which is the actual bactericide.

As the result of much experience Prof. Deycke considers that what he calls "Nastin B¹," in which one part of nastin is dissolved in forty parts of benzoyl-chloride, and this again in sterile olive oil, is the best combination, rarely, if properly administered, giving rise to reaction. A weaker solution, "Nastin B⁰," he uses in cases of ophthalmic and nerve leprosy, as a special precaution against dangerous reaction. After the weaker preparations have been used for some time a stronger nastin, B², may be employed.

There are certain points in the nastin treatment of leprosy on which Prof. Deycke lays stress: (1) Reaction from excessive doses is unnecessary and should be avoided. (2) Not too frequent injections; once a week suffices. (3) Perseverance for months and years, intermitting the injections for a month or two occasionally.

Reports from British Guiana, where systematic trial of this treatment on a large scale has recently been carried out, speak favourably of the results up to the first six months, but subsequently the disease ran its usual course and further trial of a promising therapeutic agent was abandoned. Other and similar " vaccines," such as Beauchamp-Williams's and Rost's " leproline," are on their trial.*^[5]

1. * It is to be noted that Fraser, though using the special media recommended by Bayon, Duval, and others (placental- juice agar and horse -serum nutrose-agar), and tissue swarming with leprosy bacilli, was unable to obtain any growth after prolonged cultivation.
2. * Unfortunately the Wassermann reaction is of little value, as the majority of leprous sera are said to give a positive result.
3. It has been estimated that 10 per cent. of the children of leprous parents, provided the children remain under the local conditions in which the parents lived, become lepers; if the parents emigrate to a non-endemic country before the birth of the children, this liability ceases.
4. * The drug, put up in proper doses in ampoules, can be obtained from Messrs. Smith, Stanistreet & Co.
5. * Nastin preparations may be obtained from Messrs. A. & M. Zimmermann, 3, Lloyd's Avenue, London, E.C,