Objective: To study the prevalence of latent tuberculosis infection (LTBI) in prisoners.
Methods: Among inmates admitted to a men's preventive detention prison in Barcelona during May-June 2009, without a previous positive tuberculin skin test (TST), a ≥ 10 mm TST was considered positive (5 mm in human immunodeficiency virus [HIV] infected persons). A multivariate logistic regression was performed, calculating odds ratios (ORs) and 95% confidence intervals (CIs).
Results: A total of 221 individuals were included. The average age was 33.5 years (± 8.9 SD); 61.6% were foreigners and 45.2% were heroine and/or cocaine users; 40.3% had LTBI. The infection was associated with age >40 years (OR 3.10, 95%CI 1.51-6.35) and having been born in Eastern Europe (OR 4.3, 95%CI 1.4-12.8), North Africa (OR 2.2, 95%CI 1.01-4.7), sub-Saharan Africa (OR 7.6, 95%CI 1.3-44) or Latin America (OR 3.8, 95%CI 1.5-9.3). Subjects infected with HIV had a lower risk of a positive TST (OR 0.22, 95%CI 0.04-1.07). Only 31 (14%) did not present any of these risk factors, and 8 (25.8%) had LTBI.
Conclusions: The prevalence of LTBI was very high in this study, and systematic screening of all inmates at the time of entry into the prison is therefore recommended. Excluding those who do not fall in any of the high-risk prevalence groups from the evaluation complicates the screening and is not very effective.