Prevalence of histoplasmin sensitivity in healthy adults and tuberculosis patients in southwest China.

Two hundred and seventy-one healthy students and workers and 28 hospitalized tuberculosis patients living in Sichuan Province (southwest People's Republic of China; PRC) were tested with histolyn and tuberculin. The age of the tested subjects ranged from 17 to 22 years among the students, 17 to 38, among the workers and 17 to their 70s among the patients. Thirty-eight students (24%), 21 workers (18%) and 8 patients (29%) reacted positively to histolyn, none of the differences being statistically significant. Positive reactions were significantly more frequent among students from the south of Sichuan Province (35%) than from the north (6%). The rates of positive reaction to tuberculin in the students (25%) and in the workers (27%) indicates that tuberculous infection continues to be a significant problem in southwestern PRC. The significant rate of histolyn reaction among the tuberculosis patients raises the possibility of either infection with both Histoplasma capsulatum and Mycobacterium tuberculosis, or a missed diagnosis of chronic pulmonary histoplasmosis.