Transmissibility of Tuberculosis among School Contacts: An Outbreak Investigation in a Boarding Middle School, China.

Transmissibility of Tuberculosis among School Contacts: An Outbreak Investigation in a Boarding Middle School, China. Infect Genet Evol. 2015 Mar 7; Authors: Ma MJ, Yang Y, Wang HB, Zhu YF, Fang LQ, An XP, Wan KL, Whalen CC, Yang XX, Lauzardo M, Zhang ZY, Cao JF, Tong YG, Dai EH, Cao WC 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, gene...
Source: Infection, Genetics and Evolution - Category: Genetics & Stem Cells Authors: Tags: Infect Genet Evol Source Type: research