Abstract:

Objective: To investigate the situation of latent tuberculosis infection (LTBI) among middle school and university freshmen in Guangzhou, and to provides a reference for the prevention and control of tuberculosis and the formulation of strategies in schools and universities in Guangzhou. Methods: A total of 17632 incoming freshmen (including first-year students of junior high schools, senior high schools, junior colleges and universities) from 17 middle schools and universities in Guangzhou were selected from 2018 to 2021. All of them were treated with tuberculin skin test (TST) according to the principle of informed consent, and chest X-ray examination was added to students over 15 years at the same time. Students with TST results of moderately positive and above (average diameter of induration ≥10 mm) were further added with interferon-γ release assay (IGRA); when both TST and IGRA results were positive or chest X-ray showed abnormal shadows of the lungs, others auxiliary diagnostic tests such as sputum smear or sputum culture would be used. Screening results were analyzed using descriptive epidemiological methods. Results: A total of 17204 students were actually screened, with a screening rate of 97.57% (17204/17632). There were 4449 TST positive students, with a positive rate of 25.87% (4449/17199), a general positive rate of 15.98% (2748/17199), a moderate positive rate of 7.65% (1315/17199), and a strong positive rate of 2.24% (386/17199). The TST positive rate was the highest in the senior high school group (33.81%, 1408/4165), followed by that in junior high school group (30.58%, 329/1076), the TST positive rate was the lowest in the university group (22.68%, 2712/11958), and the difference between the groups was statistically significant (χ²=353.897, P<0.001). The positive rate of TST in boys was 26.68% (2789/10452), which was significantly higher than that of girls (24.60%, 1660/6747)(χ²=35.855, P<0.001). The 1701 students with moderately positive and above in TST (i.e., the average diameter of induration ≥10 mm) were tested for IGRA, 244 were positive for IGRA, and the positive rate of IGRA with TST moderate positive and above was 1.42% (244/17199). Of the 7 students found abnormal chest radiographs by screening, 1 was negative (IGRA not done) in TST and 6 were positive (5 IGRA positive and 1 IGRA negative) in TST. In the end, 5 cases of pulmonary tuberculosis were confirmed, and the detection rate of pulmonary tuberculosis was 29.06/100000 (5/17204). Conclusion: The tuberculosis infection situation of students in Guangzhou cannot be ignored, the physical examination of tuberculosis for junior high school and high school should be strengthened, and tuberculosis patients and LTBI students should be detected in time. The combined screening of TST and IGRA helps to improve the accuracy and efficiency of screening and is cost-effective.

Key words: Mycobacterium tuberculosis, Mycobacterium infections, Tuberculin test, Immunologic tests, Students