Immigration and leprosy in Hawaii, 1960-1981.

The 140-year-old epidemic of leprosy among the people of Hawaii reached its peak at about the beginning of this century and has been subsiding ever since. A preliminary review of new cases in Hawaii in the past 15 years showed 49 among those born in Hawaii, plus 360 new immigrant cases (largely from the Philippines and Samoa), 130 of whom were of the borderline lepromatous or lepromatous (BL/L) form. Since 1970 all new cases have been treated as ambulatory patients in their home communities. A detailed review of all 95 new Hawaii-born cases in the past 21 years showed a continuing rapid decline in incidence among ethnic Hawaiian people, with a fall in the proportion of BL/L cases from its former plateau around 40% to only 20% in the last seven years. The new immigrant BL/L cases have apparently not caused a significant secondary outbreak among the Hawaiians but have caused a modest increase among groups. Among these recent non-Hawaiian secondary cases, the proportion of BL/L cases has also recently dropped so sharply that the risk of significant tertiary spread is minor. The possible role of improved nutrition in Hawaii as an influence on these recent leprosy patterns is suggested.