The fact that leprosy was endemic among some branches of the Malayo-Polynesian stock would be another argument, if any other were needed, for tracing it to a Western rather than an American origin, for we may infer from the silence of the Spanish historians, that leprosy was unknown among
the aborigines of the American continent. The primitive home of the disease was Asia and North Africa, and there is negative evidence that it was introduced into Europe somewhere between 400 and 345 B.C., in the fact that Hippocrates barely mentions the subject, and that Aristotle is the first to give an unequivocal description of the disease. On the other hand, the frequent allusions in the oldest Chinese, Syrian and Egyptian writings to a disease bearing all the marked characteristics of leprosy, seem to show that it was as common in the East in times of remote antiquity as it is at the present day. The Roman conquests carried it far and wide through Europe, until it became so terrible a scourge that nearly all the European states of the Middle Ages were driven to enact stringent laws for the segregation of lepers, which so far fulfilled their object that after the fourteenth century, when leprosy had touched its culminating point, it began to decline. The last British leper died in Shetland in 1798, and, though indigenous lepers are still occasionally met with in most of the countries of Southern Europe, the disease is extinct in all the northern states except Norway, where there were still 11,000 known lepers in 1890.
Though there are lepers in Iceland, in the Aleutian peninsula and in Kamschkatka, leprosy may be said to be a disease of tropical and subtropical countries. With the exception of a few insignificant islands, no country in the tropic zone seems to be entirely free from it. In India—the only large country in which accurate statistics have been taken—the proportion of lepers to the total population is estimated at 5 to 10,000, though errors of diagnosis and concealment have doubtless combined to make the estimate merely approximate. In China, judging from the numbers observed in the southern treaty ports, the proportion is probably higher, but both fall far short of the Fijian figure of one per cent., and the Hawaiian of one in thirty.
Nothing was known of the specific cause of leprosy until 1874, when Armauer Hansen isolated the Bacillus lepræ, a discovery which has cleared the way for formulating precise
ideas on the subjects of heredity and contagion, and the proper treatment of the leper as a public danger.
It is, of course, impossible for any organism, however small, to create itself de novo. It must come from some pre-existing germ whose habitat may be earth, air, water, beast or man, and since leprosy has never been found in any animal except man, nor in any virgin country to which a human leper has not had access, and since the arrival of a leper in such a country is followed by an outbreak of leprosy among those who have associated with him, there is little room for doubt that man acquires the germ of the Bacillus lepræ from man, and not from other animals, nor from local or climatic conditions. The most ancient, and, as it now turns out, the most correct belief, was that leprosy is contagious; the leper was unclean. Driven out from the society of men, he was compelled under heavy penalties to warn wayfarers of his approach by voice or bell. In comparatively recent times the belief arose that leprosy was hereditary, and even that it could be acquired from the soil of certain countries. The latter belief has been disproved absolutely by the behaviour of leprosy when introduced into virgin countries. The hereditary theory is also on the wane, although the Indian Commission on leprosy in the early nineties did not absolutely disprove it. If leprosy be hereditary, how explain the striking fact brought out by Hansen, the discoverer of the bacillus, that of the numerous offspring of 160 Norwegian lepers who emigrated to America none have developed the disease, or again the equally well-attested fact that children sometimes become lepers first, and their parents afterwards. Another strong argument against heredity is to be found in the fact that lepers become sterile at an early stage of the disease; unless, therefore, leprosy finds recruits in some other way than by heredity, the disease would inevitably die out in one or at the most in two generations. Moreover, leprosy is often developed quite late in life, and if the germ had been received into the system at birth, one would have to suppose that it had remained latent for thirty, forty, or even seventy years, a circumstance without parallel in pathology. In one respect, however, leprosy, like
tubercle, is hereditary; that is to say, it often shows a preference for the members of a single family, whose constitutions have some predisposing family characteristic, and who are living together, breathing the same air, and eating the same food.
LEPROSY NOT HEREDITARY
The opinion of students of the disease is now almost universal—that leprosy is communicated by contagion, and by contagion alone, though it has not yet been determined how the contagion is communicated. Very few of the nurses and doctors in leper asylums acquire the disease, and, except in one doubtful instance, every attempt to inoculate man and the lower animals with the Bacillus lepræ has failed. It may be that the leper-germ is sterile except in certain phases of the disease, and that only in favourable conditions in the recipient's health, combined with intimate contact with the leper, can the disease take hold.
Modern opinion, therefore, holds that leprosy is contagious, and, in a sense, hereditary also in so far as it tends to cling about certain families whose members show a constitutional readiness to receive it. I have dwelt upon this opinion at some length in order to show that this is precisely the view which the Fijians themselves take of the disease. A man is said to come of a kawa ni vukavuka (leprosy-stock), which implies no disgrace except among the highest families, and if he develops the disease his misfortune is regarded as one of the family traits as inevitable as the shape of his nose. At the same time he is believed to have the power of infecting others (not necessarily by actual contagion), and he was generally made to live alone or with other lepers, at a distance from the village. In Tonga the contagious nature of leprosy was fully recognized, and the lepers were isolated on separate islets or uninhabited parts of the larger islands. It is there a grave breach of good manners to apply the word leprosy (kilia) to any one in polite society, and many ingenious shifts are resorted to in order to express the meaning without using the word. In the session of the native parliament of 1891, when a member of the upper house was discovered to be suffering from the disease, and a resolution to assign an island to him