title: Transmissibility of tuberculosis among school contacts: an outbreak investigation in a boarding middle school, China.
abstract: Tuberculosis (TB) outbreak occurred in a boarding middle school of China. We explored its probable sources and quantified the transmissibility and pathogenicity of TB. Clinical evaluation, tuberculin skin testing and chest radiography were conducted to identify TB cases. Mycobacterium tuberculosis isolates underwent genotyping analysis to identify the outbreak source. A chain-binomial transmission model was used to evaluate transmissibility and pathogenicity of TB. A total of 46 active cases were ascertained among 258 students and 15 teachers/staff, an attack rate of 16.8%. Genetic analyses revealed two groups of M. tuberculosis cocirculating during the outbreak and possible importation from local communities. Secondary attack rates among students were 4.1% (2.9%, 5.3%) within grade and 7.9% (4.9%, 11%) within class. An active TB case was estimated to infect 8.4 (7.2, 9.6) susceptible people on average. The smear-positive cases were 28 (8, 101) times as infective as smear-negative cases. Previous BCG vaccination could reduce the probability of developing symptoms after infection by 70% (1.4%, 91%). The integration of clinical evaluation, genetic sequencing, and statistical modeling greatly enhanced our understanding of TB transmission dynamics. Timely diagnosis of smear-positive cases, especially in the early phase of the outbreak, is the key to preventing further spread among close contacts.
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, 100071 Beijing, PR China.
authors.forename: Mai-Juan
authors.initials: MJ
authors.lastname: Ma
authors.affiliation: Department of Biostatistics and Emerging Pathogens Institute, University of Florida, Gainesville 32611, FL, USA.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Tuberculosis, The Fifth Hospital of Shijiazhuang, 050021 Shijiazhuang, PR China.
authors.forename: Hai-Bin
authors.initials: HB
authors.lastname: Wang
authors.affiliation: Department of Biostatistics and Emerging Pathogens Institute, University of Florida, Gainesville 32611, FL, USA.
authors.forename: Yi-Fan
authors.initials: YF
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, 100071 Beijing, PR China.
authors.forename: Li-Qun
authors.initials: LQ
authors.lastname: Fang
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, 100071 Beijing, PR China.
authors.forename: Xiao-Ping
authors.initials: XP
authors.lastname: An
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, 102206 Beijing, PR China.
authors.forename: Kang-Lin
authors.initials: KL
authors.lastname: Wan
authors.affiliation: Department of Epidemiology and Biostatistics, University of Georgia, Athens 30602, GA, USA.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Whalen
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, 100071 Beijing, PR China.
authors.forename: Xiao-Xian
authors.initials: XX
authors.lastname: Yang
authors.affiliation: Southeastern National Tuberculosis Center, Division of Infectious Diseases and Global Medicine, University of Florida, Gainesville 32611, FL, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Lauzardo
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, 100071 Beijing, PR China.
authors.forename: Zhi-Yi
authors.initials: ZY
authors.lastname: Zhang
authors.affiliation: Department of Tuberculosis, The Fifth Hospital of Shijiazhuang, 050021 Shijiazhuang, PR China.
authors.forename: Jin-Feng
authors.initials: JF
authors.lastname: Cao
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, 100071 Beijing, PR China. Electronic address: tong.yignag@gmail.com.
authors.forename: Yi-Gang
authors.initials: YG
authors.lastname: Tong
authors.affiliation: Department of Tuberculosis, The Fifth Hospital of Shijiazhuang, 050021 Shijiazhuang, PR China. Electronic address: daieh2008@126.com.
authors.forename: Er-Hei
authors.initials: EH
authors.lastname: Dai
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, 100071 Beijing, PR China. Electronic address: caowc@bmi.ac.cn.
authors.forename: Wu-Chun
authors.initials: WC
authors.lastname: Cao
mesh_terms: D000293:Adolescent; D000328:Adult; D001500:BCG Vaccine / Q000627:therapeutic use; D002681:China / Q000453:epidemiology; D004196:Disease Outbreaks / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D018598:Minisatellite Repeats / Q000235:genetics; D015233:Models, Statistical; D009169:Mycobacterium tuberculosis / Q000235:genetics* / Q000472:pathogenicity; D010802:Phylogeny; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D012307:Risk Factors; D012572:School Health Services / Q000706:statistics & numerical data*; D014374:Tuberculin Test; D014397:Tuberculosis, Pulmonary / Q000453:epidemiology / Q000382:microbiology / Q000517:prevention & control / Q000635:transmission*; D055815:Young Adult
chemical_list: D001500:BCG Vaccine
keywords: Chain-binomial transmission model; Genome sequencing; Outbreak; Transmission; Tuberculosis