The dynamic change of tuberculosis infection prevalence in rural residents: 10-year follow-up of a population-based, multicentre cohort study from China.

BACKGROUND

The incidence of tuberculosis (TB) decreased significantly in recent years in China. However, the declining in the burden of tuberculosis infection (TBI) have not been systematically evaluated. The aim of this study was to elucidate the changes of TBI prevalence during the past decade.

METHODS

Based on a population-based, multicenter cohort study (LATENTTB-NSTM), a 10-year follow-up survey was conducted among registered residents (≥18 years old) at two study sites (Zhongmu and Danyang) using open-cohort design. After excluding active TB, tuberculin skin test (TST) and interferon-γ release assay (IGRA) were used to determine TBI status of each participant.

FINDINGS

Overall, 5924 eligible participants who completed the follow-up survey were included in the analysis. Compared to the age- and gender-standardized TBI prevalence determined by IGRA in 2013, the prevalence of TBI was observed to be decreased by 22·24% (from 15·11% to 11·75%) in Danyang site and by 40·86% (from 16·57% to 9·80%) in Zhongmu site in 2023. A consistently declining trend was observed as well for TBI prevalence determined by TST test. The acquisition of TBI in 10 years was assessed by the conversion rate of IGRA result in 4648 participants who participated in both the 2013 and 2023 surveys. The IGRA conversion rate in Danyang site was significantly higher than that in Zhongmu site (4% vs. 2%, p < 0·0001). The reversion rate of IGRA result was assessed as well, and no statistically significant difference was observed between the two study sites (29% in Danyang site vs. 31% in Zhongmu site, p = 0·577). Male gender was found to be associated with an increased risk of IGRA conversion as compared to female, with adjusted odds ratio (OR) of 1·46 (95% confidence interval [CI]: 1·00-2·13). In addition, never smokers were observed to be associated with significantly higher IGRA reversion rates (OR = 2·91, 95% CI: 1·52-5·57) (p = 0.001) as compared to current smokers. We also found the influence of BCG vaccination at birth on TST positivity was non-significant among individuals aged 15 and above.

INTERPRETATION

Our findings suggest that the prevalence of TBI in rural residents from China has significantly decreased along with the declining of TB incidence in the last decade. The downward trend shows regional differences, which might be partly explained by the difference in new infection rates across regions.

FUNDING

The CAMS Innovation Fund for Medical Sciences and the National Natural Science Foundation of China.