SENSITIVITY TO HISTOPLASMIN AMONG NEGRO AND WHITE RESIDENTS OF DIFFERENT COMMUNITIES IN THE USA.

The frequency of infection with the fungus Histoplasma, as judged by the results of skin tests with histoplasmin, varies widely from county to county across the USA and even over very short distances within some counties. Differences between various segments of the population, such as between Negroes and whites, living in one particular community are therefore difficult to interpret, as they might represent the effect of differences in ecological rather than in demographic factors within the community. Since the pertinent ecological differences could, however, be expected to balance out if a large number of communities were sampled, results of histoplasmin skin tests among Negro and white Navy recruits from 37 different communities are compared in the present report. The prevalence of reactors to histoplasmin ranges from zero to over 90% in residents of the different geographical areas, indicating wide variations in the ecological conditions affecting the growth and dissemination of the fungus, yet comparisons of results in Negroes and whites indicate that the factors influencing infection and sensitization of man appear to bear equally on both racial groups. Results with tuberculin PPD-S and the Battey PPD antigen in the same groups of recruits are included to supplement the results with histoplasmin.