Prevention and early detection of tuberculosis.

1,570 subjects with known TB contacts (active TB, old TB and primary infection) and individuals with no known contacts but belonging to 'defined TB risk groups' were screened at the Department of Tuberculosis Prevention at the La Fe Hospital in Valencia. The total infection rate was 40.13% and active TBC was diagnosed in 2.23% of the population screened. Infection and disease rates were significant in all the groups examined, showing the need for correct screening not only for active TB contacts but also for child primary infection contacts, old TB cases not previously screened and subjects with no known contacts but belonging to a 'TB risk group'.