Leprosy

by G. Armauer Hansen; Carl Looft

PROGNOSIS.—The prognosis is very different in the two forms. As we have already stated, both forms may recover, since all leprous products may disappear without any fresh ones appearing. In nodular cases this is a very rare exception, while it is the rule in the maculo-anæsthetic. Recurrent outbreaks are almost invariable in nodular cases, and in them, too, nephritis is an almost constant occurrence. Patients rarely live more than eight or nine years after the definite outbreak of the disease. As already remarked, we cannot state that Leprosy of itself is responsible for the end; we are rather inclined to regard the nephritis and other complications as the direct cause of death. The patients usually die long before the disease has run its course. But in the maculo-anæsthetic form the cure of the Leprosy is almost invariably the result. What remains, however, after the cure of the leprosy, is very different. We have occasionally a complete subject with vigour and good health, but usually only a miserable rudiment of a human being, with more or less paralysed and deformed hands and feet, with unclosable eyes, of which the lower part of the cornea is opaque, and from which the tears run down over the cheeks, and with paralysed facial muscles unable to close the mouth, so that the saliva constantly dribbles from it. Such cases may, however, live long and reach great ages, if under such circumstances this can be looked upon as any advantage. They die usually from some intercurrent disease.

Chapter VII.
ETIOLOGY.

There is hardly anything on earth, or between it and heaven, which has not been regarded as the cause of Leprosy; and this is but natural since the less one knows, the more actively does his imagination work. And since all that was known of Leprosy was that it was a loathsome disease, search was made everywhere for a cause. We will not linger over the older literature of Leprosy. That may be found fully dealt with in Danielssen and Boeck’s Traité de la Spedalskhed and in Hirsch’s Geographical Pathology.

Only after the work of Danielssen and Boeck can one say that Leprosy entered the ranks of the scientifically investigated diseases. At that time, in 1840, when they commenced their investigations, Humoral Pathology held the field. Most diseases were ascribed to changes in the blood, and they therefore endeavoured to establish that there was in lepers a change in the blood which they regarded as the cause of the disease symptoms, especially the node formation. These changes in the blood they believed were caused by unfavourable conditions of living, and as they were not able to find any convincing evidence of the power of infection of the disease but several of its limitations to certain families, they drew the conclusion that Lepra, as they called it, might appear spontaneously, that is to say, that the sanguineous dyscrasia which led to leprosy could be developed under unfavourable conditions of life, but that it was in most cases hereditary. It must, however, be noted that Danielssen always regarded Leprosy as a specific disease, described it as such, and sought for a specific cause, and the fact that he did not find it must be ascribed to the circumstance that microscopical technique and microscopical aids, especially the immersion lens, were at that time either insufficiently developed, or not yet discovered. The teaching of Danielssen and Boeck was everywhere adopted, especially their view of the heredity of the disease. The fish diet and damp cold theories are only attempts to explain the so-called spontaneous development of the disease, and they are founded on the fact that Leprosy is chiefly present in littoral districts and on islands.

Of other Norwegian investigators, the late Dr. Hjorth held the view that Leprosy could not be ascribed to a specific cause, and that it was certainly not hereditary. Dr. Holmsen regarded it as a specific miasmatic and non-hereditary disease, and finally Prof. Lochmann stated that it was specific, contagious, and hereditary. While Danielssen and Boeck always required a leprous ancestor in order to recognise a case as hereditary, and when this was not forthcoming, found in the presence of the disease in other branches of the family, proof of its heredity, Biedenkap, as he was unable in many of his cases to determine the existence of leprous ancestors, widened the definition of heredity by assuming that unfavourable conditions of life might produce in the organism conditions which became hereditary, and showed themselves in later generations as leprosy. In the year 1869, Dr. Drognat-Landré published a book with the title, De la contagion seule cause de la propagation de la lépre, in which he sought to prove that heredity had nothing to do with the spread of Leprosy. That is, according to our view, the right standpoint, as we shall endeavour to demonstrate.

As is seen from the above short summary of the views of Norwegian investigators, some maintain the non-specific origin and heredity of the disease; one only, the non-specific origin; one a specific cause and no heredity; and finally, one a specific cause, contagiousness and heredity.

It is rather remarkable that supporters both of the specific and the non-specific origin of the disease should regard it as hereditary. It apparently struck none of them that possibly the specificity of a disease, that is, its development through the action of a poison, might be incompatible with heredity. Since the discovery of the Lepra bacillus and its recognition in all leprous products, it is now everywhere admitted that it is the cause of the disease, and it would therefore be superfluous to indicate which of all the symptoms of the disease point to its specific nature. All this was shown in a communication made by one of us to the Copenhagen Congress in 1884. We start then from the assumption that Leprosy is a disease caused by the Lepra bacillus, although it is as yet not strictly scientifically proved, since inoculation on man and animals has not been definitely successful.

The question as to heredity now is, Can the lepra bacillus be conveyed by heredity. This is Baumgarten’s view; he holds that both Tuberculosis and Leprosy are thus spread, that the bacilli of both diseases may be transferred to the children and there remain dormant, but that they can thence be conveyed to another generation, and from it to a fourth, fifth, etc. generation, and then in the third, fourth, etc. generation become once more active and cause the disease. We see at once that this is only a modification of Biedenkap’s heredity, a peculiarity of the organism which finally becomes evident as Leprosy. In place of his undiscovered peculiarity, we have undiscovered latent bacilli. Baumgarten’s view is therefore only a hypothesis for the explanation of the origin of the two diseases. The hypothesis may be tested from two points of view: first, we may sift it theoretically; and secondly, we may investigate whether it can explain the distribution of the disease.

We must first endeavour to make clear what heredity is. As a matter of fact we do not know; we are familiar only with a series of phenomena which we call heredity, just as we have a series of phenomena which we ascribe to the force of gravity, without knowing what gravity or its force actually is. If we consider only the phenomena of heredity, which are nowhere so completely and clearly put together as in Darwin’s works, we find that he presents so-called laws of heredity, that is, he has noted the most frequent phenomena of heredity, and thence deduced a law. If the phenomena in the conveyance of a disease to one’s descendants are to be called heredity, they must correspond with the rest of the phenomena of heredity. And looked at thus, we know of no specific disease which can be called hereditary. The conditions which are hereditary are all anatomical and physiological peculiarities of the organism. A bacillus which is living in the organism cannot be regarded as one of its anatomical or physiological peculiarities; it is a parasite. Now it is beyond doubt that parasites may be conveyed from parents to children. Such are the Achorion Schönleini, and the Acarus Scabiei. But this is no hereditary communication, it is simply a present from the parent to his child. But, it is objected, if the parasite is conveyed through the organs of generation during copulation, then it is no longer a present or an inoculation, it becomes hereditary. This appears to us a remarkable argument, that conveyance by means of the organs of generation can change the nature of the parasite and convert it into an anatomical constituent of the organism of parent or child. A parasite remains always a parasite, and since its conveyance from one adult to another is called infection, we cannot comprehend why its conveyance to an ovum or a fœtus should be indicated by another name. Were Baumgarten’s hypothesis correct, it should certainly be called a hypothesis of latent infection, and not a hypothesis of heredity. We said above that we knew of no specific disease which was hereditary. To this it will naturally be objected that syphilis is a typically hereditary disease. But we reply that syphilis is a disease communicable to children, but that it is not hereditary, and in order to maintain this statement we only need to place in parallel the phenomena of the conveyance of hereditary peculiarities and those of the communication of syphilis to children, in order to make it perfectly clear how different the two methods are.

Conveyance of Hereditary Peculiarities.	Conveyance of Syphilis to Children.
1.—The hereditary peculiarity is usually limited to one sex, so that the male communicates his peculiarities to his male descendants, and the female hers to the female.	Not the case in syphilitic children.
2.—Very often, possibly always, the appearance of the hereditary peculiarity is limited to a definite age.	In the communication of syphilis to children this is unknown.
3.—Atavismus, or the overleaping of one or several generations of the heredity is very frequent.	Never known.