Timing and Predictors of Tuberculosis Incidence among Contacts

Contact investigations are crucial for tuberculosis (TB) control, yet the temporal dynamics of disease progression among exposed contacts remain poorly understood. Here, we analyzed a retrospective cohort of 44,106 contacts of 6,243 TB cases identified through the Florida Department of Health surveillance system (2009-2023). During the 15-year follow-up period, 454 individuals within this cohort developed active TB disease. Using survival analysis and mixed-effect Cox proportional hazards models, we determined that the median time to TB disease onset was 11 months following the initial contact investigation. The risk of progression to TB disease varied markedly by age and immune status. Children aged 0-5 years showed nearly seven times higher risk of TB disease progression compared to adults 65 years and older (aHR = 6.66, 95% CI: 1.33-33.27). HIV-positive contacts demonstrated a five-fold increased risk (aHR = 4.75, 95% CI: 2.43-9.30) relative to HIV-negative individuals. These findings indicate that the risk of TB transmission and disease progression persists beyond initial contact investigation activities and varies significantly across demographic and clinical subgroups, suggesting the need for extended contact monitoring and age-specific preventive strategies, particularly for young children and immunocompromised individuals.