[Relationship between the distribution of kala-azar and the natural landscape in the Nei-Monggol Autonomous Region].

From 1979 to 1982, kala azar surveys were carried out in Nei-Monggol Autonomous Region. It was found that the disease occurred only in the dry desert areas of Ejin Banner and Alxayou Banner and the mountainous areas of Ningcheng County and Harqin Banner. Kala azar cases and sandflies were absent in semi-desert and arid steppe areas. In Ejin Banner, the incidence of kala azar was 5 to 72 per 10,000 from 1972 to 1982. The natural infection of promastigotes in Phlebotomus major wui, an anthro-pophilic species, was 0.62% in 1979. In Alxayou Banner, only one case of kala azar had been found in 1973 and none since then. In Ningcheng County and Harqin Banner, a few cases had been recorded in the 50s and none since 1960. Ph. chinensis was present in these areas, though in small number. It was a peri-wild or wild species in Ningcheng County and Alxayou Banner respectively. Probably this sandfly species was a vector of kala azar in these areas.The main features of the landscape are its vegetation and soil. Comparing the natural landscape characteristics of endemic and nonendemic areas in Nei-Monggol Autonomous Region, it was found that kala azar was present only in the desert forest soil (scrubby meadow soil) area where Populus diversifolia and Tamarix sp. grew, and it waS the only area where Ph. major wui was present as the predominent species. The authors are of the opinion that the occurrence of kala-azar in Ejin Banner forest area is due to the environment which is suitable for the breeding of Ph. major wui.