Diseases that probably included the malady now known as Hansen's disease are described as leprosy in the Bible; segregation and disinfection were advocated as methods of control (Lev. 13.14). Leprosy, which may have originated in Africa or S Asia, is believed to have existed in India and Egypt earlier than 1000 B.C.; a skeleton that dates to c.2000 B.C. and that shows possible evidence of leprosy has been found in NW India. The first clearly identifiable written reference to the disease is from an Indian source c.600 B.C. Infectious diseases from the East—all called leprosy—later spread over most of Europe and the British Isles, and the Crusades were a factor in disseminating them still farther, so that by the 13th cent. they had reached epidemic proportions. Leprosariums were eventually established in most countries for the care of those actually afflicted with leprosy.
The disease still occurs in tropical and subtropical countries of Asia, Africa, and Latin America—mainly Brazil, S central Africa, and India—especially where crowded and unsanitary conditions contribute to its spread. Even in the more developed countries it crops up from time to time. In the United States, the disease is found mostly in Louisiana, Texas, Florida, Hawaii, as well as in California, the Northeast, and other areas where immigrants from endemic areas have settled. Although modern treatment is effective against the disease, the number of cases in the United States has increased significantly since the 1960s. The World Health Organization is working to eradicate the disease worldwide, but progress has been more slow than was anticipated.