Tuberculin reactivity and subsequent development of tuberculosis in a cohort of student nurses.

This retrospective study documents a strong correlation between tuberculin reactivity and the subsequent development of active tuberculosis in student nurses. 12% of the 25 student nurses with tuberculin reactions above 20 mm developed tuberculosis over a period of 2 years, compared to only 0.3% of the 341 student nurses with reactions of 20 mm or less. The implications of these findings for preventive therapy are discussed.