Objective: To analyze delay in student pulmonary tuberculosis(PTB) case finding and associated factors in Suzhou, and to provide a reference for tuberculosis outbreak prevention and control in schools. Methods: A total of 1 148 students with PTB who registered and were treated in Suzhou from 2011 to 2020 were included. Kruskal Wallis H test, 2 test and Cochran Armitage trend test were used to analyze the time trend of case finding delay. Logistic regression was used to analyze the correlation between admission characteristics and case finding delay. Results: Among the students with PTB, a total of 569 cases were found to be delayed. The rate of delay was 49.6%, and the median delay time was 26(11-49) days. From 2011 to 2020, the difference in case finding interval of students with PTB was statistically significant( Hc=54.62, P <0.05), and the difference in case finding rate was also statistically significant( χ 2=53.69, P <0.05). The rate of delay fluctuated, with an overall upward trend over time( Z=-3.67, P < 0.05). Clinical consultation( OR=5.57, 95%CI =1.91-16.27), positive etiology ( OR=1.46, 95%CI =1.14-1.86) were positively correlated with case finding delay(all P <0.05). Conclusion There are significant delays in case finding among students with PTB in Suzhou. Clinical consultation and positive etiology are associated with case finding delay. In response to the growing problems in daily school tuberculosis prevention and control, multiple departments should cooperate to implement relevant measures and to reduce the occurrence of case finding delay.

Objective: To analyze the relationship between the risk of tuberculosis outbreaks in schools and the visit interval of index cases, so as to provide a scientific reference for predicting the risks of tuberculosis outbreak and making preventive measures. Methods: A total of 630 index cases from school tuberculosis outbreaks were studied during January, 2015 to December, 2022. Data on demographics, consultation history, etiological diagnosis, and methods of detection were collected. Restricted Cubic Splines (RCS), unconditional Logistic regression, and the receiver operating characteristic curve (ROC curve) were used for analysis. Results: The RCS fitted curve showed that the risk of a tuberculosis outbreak linearly increased when the consultation interval for etiologically negative patients exceeded 5.79 days, or for etiologically positive patients exceeded 8.37 days. After multi factor adjustment, for every additional day in the visit interval of the index case, the odds ratio ( OR ) value for a high risk outbreak was 1.10 (95% CI =1.07-1.13)( P <0.05). When analyzed by tertiles of visit intervals, compared to an interval of <14 days, the OR values (95% CI ) for high risk outbreaks in schools with intervals of 14-<28 days and ≥28 days were 10.32(3.04-35.10) and 82.58( 28.42 -239.95), respectively( P <0.01), indicating a trend of increasing outbreak risk with longer visit intervals. Based on the ROC curve analysis, the optimal threshold for predicting a high risk school tuberculosis outbreak was 23.5 days, with an area under the curve ( AUC ) of 0.93 (95% CI =0.89-0.98). Conclusion An extended visit interval of index cases is a good early warning indicator for high risk tuberculosis outbreaks in schools and could be considered a key factor in early intervention and risk control strategies.