Tuberculosis transmission in a large urban jail.

Following diagnosis of moderately advanced tuberculosis in an inmate of Cook County Jail, tuberculin testing was performed to assess the degree of transmission of tuberculosis within the jail. Twenty-three percent of inmates exposed to the index patient were initially found to be tuberculin positive. Subsequent tuberculin testing three months later demonstrated a 71% rate of skin-test conversion in previously tuberculin-negative inmates exposed to the index patient. The rate of infectivity of tuberculosis within a jail is analogous to a household situation. Despite major obstacles, modern programs of tuberculosis screening and treatment are essential in correctional institutions.