Silicosis is a well-established risk factor for Mycobacterium tuberculosis infection. This study aimed to estimate the burden and risk factors of M. tuberculosis infection. Silicosis patients from Zhejiang Province were screened for M. tuberculosis by sputum culture, chest radiographs, whole-blood gamma interferon (IFN-γ) release assay (QuantiFERON-TB Gold In-Tube [QFT-GIT]), and tuberculin skin test (TST). Potential risk factors for M. tuberculosis were identified. Data for 1,659 patients were obtained from 1,684 participants. Of these, 1,656 (99.8%) were men, and the average age was 58 (54 to 63) years. The prevalence of active tuberculosis (ATB) was 6,340/100,000 (6.34%) people; the proportion of patients with latent tuberculosis infection (LTBI) was 50.6%. Age (odds ratio [OR] = 1.059, 95% confidence interval [CI] = 1.020 to 1.099, P = 0.003), being underweight (OR = 2.320, 95% CI = 1.057 to 5.089, P = 0.036), and having a history of exposure to TB patients (OR = 4.329, 95% CI = 1.992 to 9.434, P < 0.001) were associated with ATB; BCG vaccination could reduce ATB risk in silicosis patients (OR = 0.541, 95% CI = 0.307 to 0.954, P = 0.034). Among patients without ATB, the QFT-GIT positivity rate was 40.5%, which was affected by silicosis severity, while that of TST was 57.2%. BCG vaccination was an independent factor for LTBI risk reduction (OR = 0.612, 95% CI = 0.468 to 0.801, P < 0.001). The quantitative results of QFT-GIT decreased with silicosis stage (H = 6.037; P = 0.048). In conclusion, M. tuberculosis prevalence was high in silicosis patients. BCG vaccination reduced the risk of both ATB and LTBI in silicosis patients. IMPORTANCE This study evaluated the prevalence of Mycobacterium tuberculosis infection in silicosis patients in mainland China and identified the potential risk factors for both active tuberculosis (ATB) and latent tuberculosis infection (LTBI). We believe that our study makes a significant contribution to the literature because we demonstrated that M. tuberculosis prevalence was high among silicosis patients. BCG vaccination was an independent factor that reduced the risk of M. tuberculosis infection in patients with silicosis. Furthermore, we show that the prevalence of LTBI in patients with silicosis may have been underestimated by immunological detection methods. This study can help to identify targeted subgroups prioritized for M. tuberculosis control and to reduce the risk of disease development.
Keywords: BCG vaccination; Mycobacterium tuberculosis; QuantiFERON-TB Gold In-Tube; latent tuberculosis infection; prevalence; silicosis; tuberculosis.