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

Peng Lu; Feng Lu; Qiao Liu; Ling Tang; Xiaoyan Ding; Wen Kong; Wei Lu; Limei Zhu

doi:10.1016/j.ijregi.2021.10.012

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

IJID Reg. 2021 Nov 3:1:117-123. doi: 10.1016/j.ijregi.2021.10.012. eCollection 2021 Dec.

Authors

Peng Lu¹, Feng Lu², Qiao Liu^{1

3}, Ling Tang⁴, Xiaoyan Ding¹, Wen Kong⁵, Wei Lu¹, Limei Zhu¹

Affiliations

¹ Department of Chronic Communicable Disease, Center for Disease Control and Prevention of Jiangsu Province, Nanjing, Jiangsu Province, PR China.
² Center for Disease Control and Prevention of Nantong City, Nantong, Jiangsu Province, PR China.
³ Department of Epidemiology, School of Public Health, Nanjing Medical University, Nanjing, Jiangsu Province, PR China.
⁴ Center for Disease Control and Prevention of Haimen County, Nantong, Jiangsu Province, PR China.
⁵ Center for Disease Control and Prevention of Qingpu District, Shanghai City, PR China.

Abstract

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 < 15 mm (two with abnormal chest radiography scan and three with positive T-SPOT tests, confirmed by CT) and two with PPD ≥ 5 mm and < 10 mm (confirmed by CT scan through proactive visit).

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.

Keywords: CDC, Center for Disease Control and Prevention; CXR, chest radiography, CT, computed tomography; HIV, human immunodeficiency virus; PPD, purified protein derivation; TST, tuberculin skin testing; computed tomography; interferon-gamma release assay; outbreak; school; tuberculosis.