Abstract:

Objective: To analyze the current status and influencing factors of latent tuberculosis infection (LTBI) among school tuberculosis (TB) epidemic contacts of pulmonary tuberculosis (PTB) patients in Ganzhou City, and to provide a basis for optimizing TB prevention and control measures in school settings. Methods: A retrospective study was conducted utilizing clinical data collected from TB prevention and control institutions across all counties (cities and districts) of Ganzhou City between July 2022 and July 2023. Data included gender, age, presence of suspected TB symptoms, screening time, and results of the recombinant Mycobacterium tuberculosis fusion protein (EC) test among school contacts of PTB patients. The prevalence of LTBI and associated risk factors were analyzed among contacts with varying characteristics. Results: From July 2022 to July 2023, EC-based TB infection screening was conducted among contacts from 111 school TB outbreaks in Ganzhou City, involving 6748 identified contacts. Of these, 6613 (98.00%) underwent EC testing, which identified 6 active TB cases and 259 LTBI cases during the first round. Two hundred and eighty initially EC-negative contacts from classes with three or more TB cases were re-tested three months later, yielding 7 additional LTBI cases. Finally, the LTBI detection rate of the screened individuals was 4.03% (266/6607) after excluding 6 tuberculosis patients. Multivariate logistic regression analysis of 6607 screened individuals indicated that the risk of LTBI increased with age, with odds ratios (OR (95%CI)) of 2.865 (1.528-5.372) for ages 15-19, 4.174 (1.762-9.891) for ages 20-24, 14.301 (2.649-77.201) for ages 25-34, 25.674 (4.788-137.656) for ages 35-44, 39.642 (7.018-223.909) for ages 45-54, and 37.745 (6.435-221.387) for ages 55-69. Contacts of patients with positive bacteriological results had a significantly higher risk of LTBI compared with those in contact with bacteriologically negative patients (OR (95%CI)=1.468 (1.110-1.940)). Conclusion: Contact with etiologically positive tuberculosis patients is a significant risk factor for LTBI among school contacts, and the LTBI prevalence increases with age. Strengthening dynamic surveillance of latent infections and implementing sustained follow-up measures are essential to prevent and control clustered outbreaks, particularly among high-risk groups.

Key words: Tuberculosis, pulmonary, Students, public health, Contact tracing, Factor analysis, statistical, Ganzhou City