Abstract:

Objective To explore the occurrence, development and response of a tuberculosis epidemic in an university in Yangjiang prefecture, and to provide practical experience for the prevention and control of tuberculosis in schools. Methods From September to December 2019, 9 tuberculosis cases were found in an university in Yangjiang prefecture, Guangdong Province. Chest X-ray and tuberculin pure protein derivative (PPD) skin test were performed on 676 students in close contact with the patients. In the first round of investigation, 65 classmates from the “17 animation class”, roommates and teachers of TB patients were screened; In the second round of screening, 389 students from other classes that shared classrooms with the “17 animation class”, students on the same floor with TB patient’s dormitory and relevant teachers were screened. Classes that found patients in those 2 rounds were defined as the high exposure group (total 454 students in 5 classes). In the third round, 222 students from other classes in the same floor (other than the same classroom) with the “17 animation class” were screened, which was considered as the low-exposure group(222 students in 4 classes). We analyzed the epidemic characteristics, causes and treatment measures of this outbreak to discuss the causes of spread of this epidemic. Results Among those 9 patients, 4 had cough symptoms, among whom 1 had being coughing for more than half a year (suspected to be the first source of infection). In the first round of close contact screening, 65 students underwent PPD skin test, of which 11 were strongly positive (strong positive rate:16.92%), and 13 showed abnormality in chest radiograph. A total of 389 students were screened in the second round, 8 of them were strongly positive for PPD skin test (strong positive rate: 2.06%) and 5 showed abnormality in chest radiograph. In those first two rounds, totally 19 students were strongly positive, with a positive rate of 4.19%. Among the 222 students screened in the third round, 2 were strongly positive in PPD skin test, with a positive rate of 0.90% and 2 with abnormal chest radiograph; the PPD positive rate of high exposure group (4.19%, 19/454) was significantly higher than that of low exposure group (0.90%, 2/222),difference was statistically significant (χ²=4.16,P=0.040). Conclusion Close contact screening were carried out in a timely manner,the result showed that latent TB infection in high exposure group was significantly higher than that of the low exposure group.

Key words: Tuberculosis,pulmonary, Schools, Disease outbreaks, Contact tracing, Sickness impact profile