Prevalence of Pulmonary Tuberculosis and Comparative Evaluation of Screening Strategies in a Brazilian Prison

Setting: A prison (1171 male inmates) in Rio de Janeiro, Brazil.

Objectives: To determine the prevalence of active pulmonary tuberculosis (TB) and to assess the performance of several screening strategies.

Design: In a cross-sectional study, all inmates underwent chest radiographic screening. Subjects with abnormal findings underwent sputum smear examination and sputum culture. Taking this strategy as the reference, we assessed three targeted screening strategies to identify TB suspects: Strategy 1: cough >3 weeks; Strategy 2: WHO score > or = 5; Strategy 3: presence of at least one potentially TB-related symptom.

Results: The prevalence of TB cases was 4.6% (48/1052) and 2.7% for definite TB cases. If TB suspects identified by targeted screening had sputum smear examination alone, 37 (86.0%) of the 43 cases would have been missed by Strategy 1, 34/43 (79.1%) by Strategy 2 and 34/43 (79.1%) by Strategy 3. If TB suspects had both sputum smear examination and, for smear-negative subjects, chest radiography, respectively 28/43 (65.1%), 18/43 (41.9%) and 13/43 (30.2%) of cases would have been missed.

Conclusion: All three targeted screening strategies were unreliable. Given the importance of early TB diagnosis in overcrowded and highly endemic settings, routine radiography-based screening may be warranted.