Objectives: Using QuantiFERON-TB Gold In-Tube (QFT-GIT) for monitoring tuberculosis (TB) and latent TB infection treatment effect is controversial. The present study aimed to evaluate the dynamic changes of interferon gamma (IFN-g) levels along with latent TB infection treatment via a randomized controlled study. Methods: A total of 910 participants treated with 8 weeks of once-weekly rifapentine plus isoniazid (group A), 890 treated with 6 weeks of twice-weekly rifapentine plus isoniazid (group B) and 818 untreated controls (group C) were followed for 2 years to track active TB development. QFT-GIT tests were repeated three times for all groups: before treatment (T0), at completion of treatment (T1) and 3 months after completion of treatment (T2). Results: Similar rates of persistent QFT-GIT reversion were observed in groups A (19.0%, 173/910), B (18.5%, 165/890) and C (20.7%, 169/818) (p 0.512). The dynamic changes of IFN-g levels were not statistically significant among the three groups. In treated participants, individuals with higher baseline IFN-g levels showed increased TB occurrence (1.0%, 9/896) compared to those with lower baseline levels (0.2%, 2/904) (p 0.037). A similar but statistically insignificant trend was also observed in untreated controls (1.8% (7/400) vs. 0.5% (2/418), p 0.100). When TB cases were matched with non-TB cases on baseline IFN-g levels, no significant differences were found with respect to the dynamic changes in IFN-g levels with time, regardless of whether they received treatment. Conclusions: QFT-GIT reversion or decreased IFN-g levels should not be used for monitoring host response to latent TB infection treatment.

Objectives: Elderly individuals in rural China have been known to be at increased risk of contracting tuberculosis (TB) and developing active disease. This study aims to estimate the burden of mycobacterium tuberculosis (MTB) infection and to identify potential targeted subgroups for infection control. Methods: As part of the investigation of an interventional study, 50-to 70-year-old rural residents in Zhongmu County were targeted for MTB infection testing using QuantiFERON-TB Gold In-Tube (QFT). Questionnaires and physical examinations were conducted to acquire their demographic information and health status. Results: A total of 20 486 individuals were included in the analysis. The prevalence of QFT positivity was 20.79% (4259/20 486) and 50 participants (0.24%) had indeterminate results. A positive doseeresponse relation was found for QFT positivity with smoking intensity. Compared with non-drinkers, the risk of MTB infection was lower among participants with moderate alcohol consumption (<10 g/day) with adjusted odds ratio (OR) of 0.82 (95% CI 0.71e0.94). In addition, gender of male, with a history of previous TB or silicosis, and hepatitis B/C virus infection were associated with increased risk of MTB infection. An indeterminate QFT result was related to being underweight (adjusted OR 3.18; 95% CI 1.09e9.26). Conclusions: Our results indicate a high burden of MTB infection among the elderly in this rural area. Smokers, individuals with a history of previous TB or silicosis, and those with hepatitis B/C virus infection should be prioritized for MTB infection control to reduce the risk of disease development from a new infection.