Objective: To identify precipitating factors of a tuberculosis (TB) outbreak in a school and discuss the importance of index case detection on outbreak monitoring, follow up and related control measures.
Methods: A case survey of the index patient was conducted to evaluate the illness severity and infectious duration of the case. The initial response to this case was surveyed to understand the factors leading to the outbreak.
Results: A total of 25 TB cases were detected in the outbreak, including 14 cases in one class. The risk of catching TB among the classmates of the index case was 10.74 times higher than that among students in other classes (χ² = 42.31, P < 0.001). Although the index case had typical TB symptom of cough and expectoration, TB was not diagnosed until pulmonary cavity was detected by chest radiograph one month later. Among 64 close contacts, 56 (87.5%) completed TB screening, 52 (92.9%) were purified protein derivative positive. No TB cases were detected.
Conclusion: The factors leading to the outbreak included delayed diagnoses of the index case, no chemoprophylaxis taken by the close contacts;poor surveillance and follow-up for close contacts.