Abstract
Contact investigation is an important and effective active case-finding strategy, but there is a lack of research on congregate settings in countries with an intermediate incidence. This study determined the incidence of and risk factors for tuberculosis (TB) development after exposure in congregate settings. This retrospective cohort study included 116,742 contacts identified during the investigation of 2,609 TB cases diagnosed from January to December 2015. We searched the Korean National Tuberculosis Surveillance System TB registry to identify contacts that developed active TB during follow-up until May 2018. During the mean observation period of 2.9 years, 499 of 116,742 contacts (0.4%) developed new active TB. From these contacts, 404 (81.0%) developed TB within 2 years after exposure. The 2-year Kaplan-Meier cumulative risk for TB was the highest in contacts aged ≥65 years [1%; 95% confidence interval (CI), 0.8–1.3]. Contacts with LTBI who completed chemoprophylaxis exhibited a lower risk of active TB development than those without chemoprophylaxis (adjusted hazard ratio, 0.16; 95% CI, 0.08–0.29). Aggressive contact investigation is effective for the early detection and prevention of TB in congregate settings. The risk of progression to active TB among contacts with LTBI can be minimised by the completion of chemoprophylaxis.
Highlights
Tuberculosis (TB) imposes a high global disease burden, with more than 10 million new patients and 1.6 million annual deaths worldwide[1]
We analysed the TB incidence in individuals who had contact with active TB cases in congregate settings in the Republic of Korea (ROK) and sought to confirm the risk factors that influenced the development of TB in these cases
The overall incidence in contacts was almost seven times higher than that in the general population of the ROK in 2015 (63 per 100,000 persons)[3], and the incidence in contacts who tested positive for latent TB infection (LTBI) was 22 times higher than that in the general population
Summary
Tuberculosis (TB) imposes a high global disease burden, with more than 10 million new patients and 1.6 million annual deaths worldwide[1]. The global burden of latent TB infection (LTBI) was 23.0%, amounting to approximately 1.7 billion people. 5–10% individuals with LTBI develop active TB in their lifetime, with 50% developing active disease within 2 years after infection[4,5,6]. The World Health Organization (WHO) recommends that tests and treatments for LTBI should be prioritised for contacts of TB patients[7]. The present study aimed to analyse the TB incidence in individuals who had contact with TB cases in congregate settings and evaluate the risk factors that influence the development of TB among these contacts
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