Application of the “TST-IGRA” two-step method in screening close contacts of active tuberculosis patients among three high schools / 公共卫生与预防医学

ABSTRACT

Objective To explore the application of the TST-IGRA two-step method in the screening of close contacts of active tuberculosis patients among three high schools in Jinshan District in 2020-2021，and to provide evidence for improving the prevention and control of tuberculosis in schools. Methods Three school tuberculosis outbreaks in Jingshan District from 2020 to 2021 were included in the present study. After excluding active tuberculosis, tuberculin skin test and γ-interferon release assay (IGRA) were conducted to screen latent infection of Mycobacterium tuberculosis in close contacts, and the necessity of the two-step method was analyzed. Results A total of 362 close contacts were screened in the three outbreaks, and 350 people were tested by TST. Comparing the results of TST and IGRA among different types of close contacts, it was found that the positive rate of TST in teachers was higher than that in students（54.84% vs 20.38%，P<0.05）. The positive rate of TST among students from high-burden areas of pulmonary tuberculosis in Shanghai was higher than that of local students（24.71% vs 18.80%，P<0.05). IGRA detection was performed on those with moderate and strong positive TST results, and the results showed that the positive rate of IGRA in those with strong positive TST results was only 17.7%, with Kappa value of 0.3. Conclusion The prevention and control of tuberculosis in school should strengthen the annual health examination of teachers and staff, promote timely medical treatment for suspected tuberculosis symptoms, reasonably increase the screening frequency of students in high-burden areas of tuberculosis in Shanghai, and collect students’ previous history of tuberculosis exposure. When screening close contacts, after excluding active tuberculosis, it is recommended that TST and IGRA should be combined to determine latent Mycobacterium tuberculosis infection and achieve accurate intervention.