Regional patterns in the incidence of aplastic anemia in Thailand

The annual incidence of aplastic anemia has been determined in a rigorous a nd standardized epidemiologic study conducted in Thailand. A total of 374 c ases were identified over a period of 3-6 years in three geographically def ined and distinct regions of the country; Bangkok, Khonkaen in the northeas t, and Songkla in the south. The incidence was 3.9 cases per million person s in Bangkok, 3.0 per million in Songkla, and 5.0 per million in Khonkaen, These rates are as high or higher than in any region of Europe or Israel as reported in the International Agranulocytosis and Aplastic Anemia Study, i n which the methods and case definition were the same. Rates were stable ov er the course of the study. There were marked differences in incidence betw een northern and southern rural regions of Thailand, and among Bangkok subu rbs. These differences, together with an unusual peak in the incidence amon g young people in Bangkok, suggest the possibility of occupational and envi ronmental factors in the etiology of aplastic anemia. Am. J, Hematol, 61:16 4-168, 1999. (C) 1999 Wiley-Liss, Inc.