A tuberculosis school outbreak in China, 2018: reaching an often overlooked adolescent population

Abstract

Adolescents have been largely neglected from tuberculosis control efforts. In low- to medium burden settings much of the tuberculosis burden in this age group occurs from school outbreaks. We report on a large tuberculosis outbreak in adolescents from a boarding high school in Jiangsu Province, China. From March to June 2018, a tuberculosis outbreak occurred in a boarding high school. We conducted an outbreak investigation involving clinical diagnostic tests and molecular analysis to determine the outbreak origin. Cases were detected through symptom screening, tuberculin skin testing (TST), chest radiography, sputum smear, solid sputum culture and GeneXpert MTB/RIF. Mycobacterial interspersed repetitive-unit-variable-number tandem-repeat (MIRU-VNTR) genotyping and spoligotyping methods were performed on Mycobacterium tuberculosis (M. tuberculosis) isolates to identify the outbreak origin. A total of 845 students and 131 teachers/staff attended a TST screening for tuberculosis infection. The prevalence of elevated tuberculin reactions at ≥5, ≥10 and ≥15 mm was 12.19% (119/976), 6.35% (62/976) and 3.28% (32/976), respectively. Radiographic abnormalities were present in 5.73% (56 of 976) individuals, 40 students and 16 teachers/staff. Of these, 12 students were diagnosed with confirmed tuberculosis. In total, 14 students (two index cases and 12 confirmed cases) were diagnosed and reported in the tuberculosis outbreak, an attack rate of 1.7% (14/847) among students (two index cases and 845 screened students). Results from MIRU-VNTR typing and spoligotyping analyses demonstrated that three M. tuberculosis strains belong to the Beijing family with corresponding MIRU-VNTR alleles. This school-based tuberculosis outbreak among adolescents demonstrates that transmission among individuals in this age group is common and must be prioritised. It suggests that identifying and timely diagnosis of smear-positive cases, especially in the early phase of outbreaks, is the key to preventing further spread among close contacts.

A Prospective Cohort Study on the Prevalent and Recurrent Tuberculosis Isolates Using the MIRU-VNTR Typing

“…Each MIRU locus was amplified individually with primers specific for sequences flanking the MIRU units ( Supplementary Table S1 ). In the current study, we used a set of 12 VNTR loci ( 20 , 21 ). The PCR reaction mixture for all loci was listed in Supplementary Table S2 .…”

Tuberculosis in Adolescents and Young Adults: Emerging Data on TB Transmission and Prevention among Vulnerable Young People

“…Unsurprisingly, the risk of TB transmission among AYA in schools increases with increasing proximity and duration of exposure. Contact investigations that recorded classroom seating charts found that students who were routinely seated next to a student with TB had the highest incidence of TB infection [26,79,80]. School building designs that reduce shared air may conversely limit transmission, as with one outbreak that affected only a single classroom that opened directly to the outdoors and did not share a corridor with other classrooms [80].…”

“…School-based transmission from an adult teacher to an adolescent student with fewer than 10 h of contact has also been reported [83]. Delayed discovery of active TB cases and delayed contact investigations feature in many school outbreaks, leading to extensive spread of infection [26,[78][79][80][82][83][84][85].…”

Pulmonary Tuberculosis Outbreak in a High School, China

“…Current measures to prevent and control of TB are often focused on adults, while adolescents are often neglected in China. In recent years, some school based TB outbreaks have been reported in China [2][3][4][5][6][7], which attracts considerable attention. Data from released annual report on surveillance of infectious disease in China in 2017, 835193 TB cases were notified in China, among which, 40656 (4.87%) were students, incidence of pulmonary TB was 15.47/100000 students, and incidence of smear positive of pulmonary TB was 2.64/100000 students, the proportion of laboratory confirmed TB ranged from 8.3% to 20.8% [8].…”

“…Data from released annual report on surveillance of infectious disease in China in 2017, 835193 TB cases were notified in China, among which, 40656 (4.87%) were students, incidence of pulmonary TB was 15.47/100000 students, and incidence of smear positive of pulmonary TB was 2.64/100000 students, the proportion of laboratory confirmed TB ranged from 8.3% to 20.8% [8]. In China, high school students face serious challenge for college entrance examination, because of high pressure and overcrowded conditions, school based TB outbreaks usually occurred in boarding school system [2,7]. Diagnosis of tuberculosis in students often relies on symptoms screening, chest radiography and smear examination, and the low proportion of laboratory confirmed TB and few of positive strains isolated from TB students, which make transmission investigation more difficult.…”