Tuberculosis Contact Investigations in 2025

Tuberculosis (TB) is an airborne infectious disease that requires early detection and contact management to prevent community transmission. Timely diagnosis and treatment of latent tuberculosis infection (LTBI) can reduce the risk of progression to active TB. This study analyzed the results of TB contact investigations conducted in 2025 to evaluate the status of contact management and provide baseline evidence for future TB control policies.

Household and congregate setting contacts of patients with pulmonary TB registered in the Korea Tuberculosis Network System in 2025 were analyzed. The analysis included contacts, additional TB cases, and individuals diagnosed with LTBI, with findings stratified by age group and congregate setting type.

A total of 100,124 contacts from 15,280 households and 3,617 congregate settings were investigated, resulting in the early detection of 233 additional TB cases (232.7/10⁵ contacts). The rate of additional TB cases was highest among contacts aged ≥80 years (496.0/10⁵ contacts). LTBI was diagnosed in 13,797 individuals (24.7%), and 6,933 of 12,524 eligible individuals (55.4%) initiated treatment. LTBI rates increased with age, whereas treatment initiation rates decreased with age.

Contacts aged ≥80 years had the highest rates of additional TB cases and LTBI but the lowest treatment initiation rate, highlighting the need for active screening and improved treatment uptake in older contacts. Although the LTBI treatment initiation rate improved compared with the previous year, a sustained management system to support treatment completion is required. The Korea Disease Control and Prevention Agency plans to strengthen age-tailored management for this age group, support LTBI treatment among contacts of patients with multidrug-resistant TB, and enhance follow-up among untreated individuals.