High rate of transmission in a pulmonary tuberculosis outbreak in a junior high school in China, 2020

Background School tuberculosis outbreaks are common in China. This study aimed to introduce a new screening process to help control outbreaks. Methods An epidemiological investigation into a school-based tuberculosis outbreak was conducted in order to identify the origin of the infection, and how it was transmitted. Results In total, 10 confirmed active tuberculosis cases were diagnosed among student contacts in the index case's class, giving an incidence rate of 19.2% (10/52). Three were found through a proactive visit and seven through screening. Of the nine secondary cases, two had purified protein derivation of tuberculin (PPD) ≥ 15 mm or blister (confirmed by computed tomography (CT) scan before preventive therapy), five had TST ≥ 10 mm and Conclusion Further to our results based on this school outbreak, a new screening process is recommended that involves conducting interferon gamma release assays on those students with PPD ≥ 5 mm and < 15 mm if there are three or more active tuberculosis patients in the class with an epidemiological link. Furthermore, a CT scan is recommended for students who have had a recent tuberculosis infection before they have preventive therapy.