Abstract:

Objective To analyze an outbreak of tuberculosis (TB) in an adult education centre in Tianjin, and to provide evidences for formulating disposition measures of school TB.Methods The information of an epidemiological investigation and screening on the outbreak of TB in the adult education center in Tianjin from October 2017 to April 2018 were collected, and the epidemiological characteristics, causes and disposition measures of the epidemic were analyzed.Results The center had organized three rounds of screening for close contacts by tuberculin skin test and chest X-ray examination since the first case was found. Seventeen students were diagnosed as TB in succession. The first two cases were detected by passive identification, and the remaining 15 cases were detected by screening. The 17 confirmed cases were distributed in five classes, mainly in the class of the first case (12 cases (52.2%) were detected among the 23 students in the class). Two cases (1.3%) were diagnosed as TB among 159 students in other classes on the same floor. The risk of TB infection in the class of first case was 86.73 times higher than other classes (95%CI: 17.22-436.87; χ ²=67.19, P<0.01). Among the ten students in the dormitories of the first and second smear-positive cases, eight were diagnosed as TB. Four of the 129 students in the dormitories on the same floor were diagnosed as TB. The risk of TB infection in the dormitories of the first two cases was 125.00 times higher than other classes (95%CI: 19.82-788.44; χ ²=60.17, P<0.01). In the outbreak, the diagnosis rates of abnormal chest X-ray and strong positive TB skin test were 66.7% (10/15) and 11.0% (16/145), respectively.Conclusion Poor ventilation is easy to cause the spread of Mycobacterium tuberculosis. The students with TB cannot be detected and put in quarantine as soon as possible, which is likely to cause infection and morbidity of contacts in the same classes and dormitories. During the outbreaks, the positive predictive value of screening measures is high so that the students with abnormal test results should be given special attention.

Key words: Tuberculosis,pulmonary, Students, Disease outbreaks, Epidemiology