ECOLOGIC STUDIES OF HISTOPLASMOSIS1

Abstract

The 1st study showed only slight variations in the histoplasmin sensitivity rates among farm families in Boone County, Missouri. Soil studies on these farms provided evidence that Histoplasma capsulatum may be isolated from sites on a farm but these sites may not result in infection of man or animals. The 2nd study demonstrated marked variations in the histoplasmin sensitivity rates among cattle in Johnson County, Kansas. Two adjacent areas in the county were found, 1 with 184 cattle negative to the histoplasmin skin test; the other with 183 cattle with 33 (18%) positive to the histoplasmtn test. H. capsulatum was isolated from 8 of 325 (2%) wild animals collected on farms in the positive area; no isolations were made from 83 wild animals collected on farms in the negative area. A total of 217 soil specimens from farms in the positive area were negative when cultured, while H. capsulatum was isolated from 2 of 99 (2%) soil specimens from farms in the negative area.