The Investigation of a TB Cluster in a School, 2007

Mei-Ying Liu

2009 Vol.25 NO.2

Correspondence Author: Mei-Ying Liu


Early in November 2007, a hospital worker who contacted a TB patient had felt ill. Immediately, National Communicable Disease Notification System released this message. After initial study and research with our database, we found this index case was a graduate from “A” school in June 2007. Among 45 graduates in that class, a total of 6 students were notified as tuberculosis cases between July and November, 2007. A further expanded outbreak investigation was conducted which including confirmation of the name list of all the teachers, students and parents of the class and collection of all related information. After the cross examination of Mycobacterium tuberculosis strains for sputum cultures positive, we found two waves of outbreaks that occurred in the class during December 2005 to November 2007, in which 10 students and 2 parents were notified. The genotype analysis of Mycobacterium tuberculosis strains indicated that the genotypes of 2 cases at the first outbreak in 2005 and 4 cases at the second wave of outbreak in 2007 were the same. Therefore, it was identified as a campus outbreak. The risk of morbidity for those students is 1,000 times higher than the same age students. A total of 9 counties and cities of public health and medical institutions cooperated and took six months to complete all students’ data tracking. Other than one student who was notified as a tuberculosis case because of abnormal chest X-ray findings in July 2008, no other cases had been reported. On May 31, 2007, the definition of TB outbreaks was extended from cases occuring within one month to one year. This should be more effective in identifying outbreak. This outbreak had now been followed sufficiently and would need to continue the usual follow up from now.
Keywords: tuberculosis, contact investigation, clusters