Risk Factors for School Tuberculosis Outbreaks

DOI: 10.6525/TEB.20160322.32(6).002

Po-Wei Chu, Jen-Hao Cheng, Chien-Ban Hsu,Pin-Hui Lee, Chang-Hsun Chen

2016 Vol.32 NO.6

Correspondence Author: Po-Wei Chu

  • Division of HIV/AIDS and TB, Centers for Disease Control, Ministry of Health and Welfare, Taiwan


This report described results from a case-control study involving 95 suspected tuberculosis (TB) outbreaks reported during 2011–2013. A confirmed outbreak was defined as a cluster with at least two TB patients having matched genotypes of Mycobacterium tuberculosis. Patient demographics, epidemiologic links, and clinical characteristics were extracted from National TB surveillance system and outbreak investigation reports. We used logistic regression to describe risk factors of being confirmed as an outbreak.

Twenty four (25.3%) of the 95 suspected events were confirmed outbreaks. Suspected events were most likely to become outbreaks if the index patient was sputum smear positive (OR 4.67, 95% CI 1.1928.25); the index patient was with delayed medical care (symptomatic or with abnormal chest radiography for more than six months before TB notification) (OR 13.17, 95% CI 1.53113.06); or a second patient in the event was a contact of the index patient (OR 11.153, 95% CI 2.5848.28). Events with a female index patient was less likely to become an outbreak (OR 0.19, 95% CI 0.050.75). 

We recommend review of routinely reported data to identify high-risk school events that are likely to be confirmed outbreaks. For these events, public health officials should implement interventions before the genotyping results are available.

Keywords:Tuberculosis, Outbreak, Case-control study, Risk assessment