Nontuberculous Pulmonary Calcification and Sensitivity to Histoplasmin

Abstract

Tuberculin and histoplasmin skin tests were performed on 3,105 student nurses in various cities. The proportion of positive reactors to histoplasmin varied from 6% in Minneapolis to 66% in Kansas City, Mo. Histoplasmin reactions are common in the eastern central region of the country, where Selective Service data have shown pulmonary calcification to be particularly prevalent. Of the 294 nurses in this study with pulmonary calcification demonstrated by X-ray, only 21.4% had positive tuberculin reactions, while > 90% reacted to tuberculin or histoplasmin or both. The results are interpreted as indicating that mild, hitherto unrecognized infection with Histoplasma capsulatum (or an immunologicalty related organism) is widely prevalent in certain States, and that this disease accounts for a high proportion of the pulmonary calcification observed in roentgenograms of tuberculin-negative persons.