Page:Tropical Diseases.djvu/661

XXXVI] 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.