Outbreak of Multidrug-resistant Tuberculosis in Two Secondary Schools

Prevalence of tuberculosis infection among contacts of drug-resistant tuberculosis patients: A systematic review and meta-analysis

INTRODUCTION

Contact investigations with drug-susceptible tuberculosis (DS-TB) patients have demonstrated a high prevalence of tuberculosis infection (TBI). However, the prevalence of TBI among individuals in close contact with drug-resistant tuberculosis (DR-TB) patients is poorly understood. This systematic review and meta-analysis aimed to determine the prevalence of TBI among household and non-household contacts of DR-TB patients.

METHOD AND ANALYSIS

We searched five databases (Medline, Embase, Scopus, Web of Science, and Cumulative Index to Nursing and Allied Health Literature (CINAHL)) from inception to 2 June 2023. All studies that reported the prevalence of TBI among DR-TB contacts were included in the study. A random-effects meta-analysis was conducted to estimate the pooled prevalence of TBI with a 95% confidence interval (CI). Sub-group analyses were conducted using study characteristics as covariates.

RESULTS

Thirty studies involving 7659 study participants from 19 countries were included. The pooled prevalence of TBI among DR-TB contacts was 36.52% (95% CI: 30.27-42.77). The sub-group analysis showed considerable heterogeneity in the estimates, with the highest prevalence reported in Southeast Asia (80.74%; 95% CI: 74.09-87.39), household contacts (38.60%; 95% CI: 30.07-47.14), lower-middle-income countries (LMICs) (54.72; 95% CI: 35.90, 73.55), children (43.27%; 95% CI: 25.50, 61.04), and studies conducted between 2004 and 2012 (45.10; 95% CI: 32.44, 57.76).

CONCLUSION

The prevalence of TBI among DR-TB contacts was high, with substantial regional variations. Further research is needed to determine the drug susceptibility status of TBI in DR-TB contacts.

PROTOCOL REGISTRATION

The protocol is registered in PROSPERO (CRD42023390339).

Whole-genome sequencing and epidemiological analysis of a tuberculosis outbreak in a high school of southern China

Tuberculosis (TB) is a serious global public health threat, and school-clustered outbreaks are common. Here, we report a TB outbreak in a high school in southern China, which was confirmed and characterized by traditional epidemiological methods and whole-genome sequencing (WGS) of Mycobacterium tuberculosis isolates. All students and faculty (n = 287) were screened by chest X-ray for active TB. TB was diagnosed in 28 patients, according to laboratory confirmation (n = 11) of Mycobacterium tuberculosis, sputum/bronchoalveolar fluid culture, smear, or TB-Xpert. Clinically diagnosed TB cases (n = 17) were further defined by the interferon-γ releasing assay or clinical and radiological findings. Twenty-five of the affected individuals were 12th grade students aged 16 to 19 years; among them, 24 patients were male and 21 had visited the internet café near the school. WGS and phylogenetics analysis confirmed that the outbreak was mainly caused by a super transmission strain of lineage 4.2, which was susceptible to all tested antibiotics. After a treatment regimen of 9 to12 months, all 28 patients were cured. This study highlights the key factors contributing to school-clustered TB outbreaks mainly derived from a single super transmission strain, along with effective interventional measures to prevent a larger scale outbreak.

Diagnostic delay as main contributing factor to a large outbreak of tuberculosis in a university

OBJECTIVE

To describe the epidemiological characteristics of a large tuberculosis outbreak in the university environment and the main risk factors associated with it.

METHOD

A descriptive analysis of the data collected from sick individuals and their contacts was made. For the contact tracing, the guidelines established in the Tuberculosis Programme of the Autonomous Community of the Basque Country were followed. Six of the outbreak strains were sent to the National Centre of Microbiology for molecular typing.

RESULTS

The total number of cases of the outbreak was 11. The rate of tuberculosis infection in the classroom of the index case, including the sick individuals, was 88.1% (59 infected and only 8 uninfected). The diagnostic delay of the index case was 260 days, and in the other 8 symptomatic cases it ranged between 10 and 70 days. The pattern obtained by the 2genotyping techniques was identical in the 6 strains studied.

CONCLUSIONS

The long diagnostic delay of the authentic index case, which was diagnosed in the contact tracing, and the poor ventilation conditions of the classroom, determined the high number of secondary cases associated with this outbreak.