Endemism of Coccidioidomycosis in the Paraguayan Chaco.

Skin testing of 541 men with coccidioidin was carried out in an investigation of endemism of coccidiodomycosis in the Paraguayan Chaco. In two areas where the climate is hot, dry and windy, positive reactions developed in a considerable number of the employees of an oil company who were of various racial origins, as well as among native Indians. In a third area, where rain is more plentiful and vegetation lush, only 2 per cent of 250 Indians tested had positive reaction to coccidioidin.