Setting: The prison population is considered to be at high risk of tub
erculosis infection and illness. Therefore, a tuberculosis prevention
and control program was put into effect upon the opening of a penitent
iary center in Barcelona whose inmates suffered a high prevalence of i
ntravenous drug use (IVDU) (48.4%) and HIV-1 infection (36.0%). Object
ive: To ascertain the prevalence of tuberculosis infection and pulmona
ry tuberculosis detected on admission to jail among those prisoners wh
o had no history of tuberculosis; and to study as predictors of tuberc
ulosis infection and illness the variables age, IVDU and HIV-1 infecti
on. Design: Cross-sectional study. Results: Of the 729 prisoners studi
ed, 56.2% were considered infected with Mycobacterium tuberculosis. Ag
e was the only variable associated with the infection, with an Odds Ra
tio (OR) of 1.017 per year (Confidence Interval [CI] 95% = 1.006-1.029
) (P = 0,004). The rates of HIV-1 and M. tuberculosis co-infection, wh
ich may run between 18.9% and 21.7%, reached 42.8% in the IVDU. A 2.7%
prevalence of pulmonary tuberculosis was observed. The most accurate
logistic regression model for pulmonary tuberculosis diagnosis (P = 0.
09) includes the variables tuberculosis infection (OR = 13.00; CI 95%
= 1.7-98), IVDU (OR = 2.60; CI 95% = 0.66-7.81) and age (OR = 1.05; CI
95% = 0.99-1.11). Conclusion: Given the high prevalences observed, we
propose the activation and maintenance of programs designed to seek o
ut and identify cases of M. tuberculosis infection and illness within
the prison population.