The Bacillus Lepræ has now been recognised in all leprous products, and although the fact has not yet been experimentally demonstrated, we may practically say with confidence that Leprosy is a chronic disease caused by the Lepra bacillus.
Leprosy appears in two forms, which are clinically pretty sharply distinguishable, and were named by Danielssen and Boeck “nodular” and “anæsthetic.” This nomenclature, introduced by these authors in their pioneer work, Om Spedalskhed, Christiania, 1847, Traité de la Spedalskhed, Paris, 1848, is so far important as it characterizes the common and most prominent symptoms of the two forms, viz., in the one, the nodular eruption on the skin, in the other, the anæsthesia which results from the widespread affection of the nerves. On the other hand, regarded from a strictly scientific standpoint, the nomenclature is scarcely the happiest: firstly, because the one form is named from the eruption on the skin, and the other from the results of the affection of another organ, the nerves; and secondly, because the nerves are affected in the nodular as well as in the other form, though the result of the affection, the anæsthesia, does not so dominate the appearance of the disease.
As Danielssen and Boeck recognised, skin eruptions are present in both forms, and since, as we shall later point out, the eruptions differ both clinically, and also somewhat in their anatomical formation, it would perhaps be more strictly correct to describe the two forms as Lepra tuberosa (tuberculosa) and Lepra maculosa or lævis. But, in the first place, it is of questionable advantage to change a universally accepted nomenclature; and secondly, it is very frequently the case that one sees the patient for the first time after the disappearance of the macular eruption with anæsthesia only, so that the name Lepra anæsthetica exactly describes the case. But in order to give to the skin eruption in the anæsthetic form its proper place in the nomenclature we will describe the two forms of the disease as Lepra tuberosa (tuberculosa), and Lepra maculo-anæsthetica. And thus we hope to have done justice both to the founders of the scientific study of Leprosy, and to the clinical appearances of the disease.
Danielssen and Boeck have also described a mixed form of the disease, in which nodular Leprosy is combined with anæsthetic. Sometimes the skin eruption disappears and the nodular form passes into the anæsthetic, and sometimes, though much more rarely, the anæsthetic into the nodular; and since, further, the two forms are so different in their clinical appearances that they look almost like different diseases, the recognition of a mixed form might appear to be justified. But since every case of nodular Leprosy is accompanied by affection of the nerves and anæsthesia; and the natural termination of every case of nodular Leprosy is to pass into the anæsthetic form, if only, as occasionally happens, the patient live long enough; and since the skin eruptions of the maculo-anæsthetic form are characterized, just as those of the nodular form, by the presence of the leprosy bacillus, we regard the transformation of a case of maculo-anæsthetic into nodular Leprosy only as a sign of the unity of the two forms, and we delete altogether the name of mixed Leprosy. Otherwise every case of nodular Leprosy must, at all events after some years of existence, properly be called “mixed,” for in such cases anæsthesia is never absent.
It has been attempted to indicate as a special form of the disease a Nervous Leprosy, in which no characteristic skin affection is present.[1] In view of what we have noted above, that nerve Leprosy is present in both forms of the disease, and that an eruption may be noted at some period in all carefully observed cases of the disease, this attempt to indicate a special nerve Leprosy is evidently wrong.
We will first of all discuss separately the two forms of the disease, the nodular and the maculo-anæsthetic, and then proceed to demonstrate the unity of the disease in spite of the differences in form.
Chapter II.
NODULAR LEPROSY.
Nodular Leprosy (Lepra tuberosa, L. tuberculosa) is usually easily diagnosed by its characteristic skin affection.
The leprous nodes or nodular Lepromata are of different size and colour; their consistence is at first firm and hard; they are but slightly compressible, and show little elasticity. Their form is usually semi-spherical, but they are often oblong. The smallest nodule that we have seen was not more than 1-2 mm. in diameter, and its appearance was so little characteristic, that we had to confirm the diagnosis by excision and microscopical examination. The larger the nodules, the more characteristic is their appearance. As they are almost always seated in the cutis, the epidermis over them is stretched and shiny; it is occasionally normal in colour, but usually at first reddish, later becoming yellow. The localisation of the nodules is usually characteristic. They are generally first evident on the face, on the backs of the hands, and on the dorsal surfaces of the wrists, and next on the extensor surfaces of the limbs. They are more rarely seen on the back and nates; on the flexor surfaces of the extremities, on the breast, abdomen, scrotum, and penis, they are quite exceptional; and we have never seen them on the glans penis, the palms or soles, or on the hairy scalp. Leloir has described a leprous affection of the palms of the hands, of which he himself says that it closely resembled a syphilide in that situation. Since Danielssen, with his enormous experience, never saw a leprous affection of the palm of the hand, we incline to believe that the affection which Leloir observed, not only resembled, but actually was, a syphilide.
Here in Norway where the people often go barefoot, wading in streams, marshes and rivers, the backs of the feet and the under part of the calves are frequently the seat of the first leprous eruption, not so often in the form of nodules, as of a dense, regular infiltration. Now since, as we have noted above, the face and back of the hands are the usual seats of predilection for the earliest appearance of the eruption, it appears not improbable that this has its explanation in the climatic influences on these parts, possibly influenced by the structure of the skin, especially the cutaneous vessels. That there are peculiarities in the structure of the tissues, which determine the localisation of the poison, one may conclude; for certain organs are never affected with leprosy, in spite of the fact that the poison has evidently at some time circulated in the blood.