Latent Tuberculosis Infection Among Individuals with Pulmonary Fibrosis in Rural China: A Screening Study

Background: Individuals with pulmonary fibrotic radiological lesions, indicating prior tuberculosis (TB), have been suggested to be at high likelihood of developing active disease from latent TB infection (LTBI). The burden of LTBI among this specific population has been rarely studied in China. Methods: : We conducted a population-based screening study to investigate the prevalence of fibrotic radiological lesions and their TB infection rate among rural residents in China. Chest radiography examination was performed for all eligible participants, and Interferon Gamma Release Assay (IGRA) testing was conducted for those with a history of anti-TB treatment and those with radiographic abnormalities suggestive of prior TB. Risk factors associated with the present of fibrosis and IGRA positivity were analyzed. Results: : A total of 45,901 rural residents participated in the study, 2,231 of them reported a history of anti-TB treatment. The prevalence of pulmonary fibrosis was 34.16% (762/2,231) and 2.81% (1,230/43,670) among the participants with and without anti-TB treatment. The present of fibrosis was found to be more frequent among individuals with a history of relapse of TB (50.35%, 72/143) or previous smear positive TB (44.23%,157/355). Among participants with fibrotic radiological lesions, IGRA positivity was 50.39% (384/762) and 25.44% (313/1,230) for those with and without anti-TB treatment records, respectively. Males, younger age and a previous smear positive TB were associated with higher IGRA positivity among individuals with anti-TB treatment record. Conclusions: : Individuals with fibrotic radiological lesions and their remarkably high burden of TB infection should be attached more attention for TB control in China.