Although it is well-known that household contacts of tuberculosis patients are highly susceptible to contracting the disease, there is a dearth of published evidence focusing on this high-risk group within low-income and middle-income countries. This study aimed to fill this gap by utilizing nationwide data from Brazil to estimate the incidence of tuberculosis and explore the socioeconomic and clinical factors influencing its occurrence among a cohort of tuberculosis patient contacts.

In this cohort investigation, researchers linked individual socioeconomic and demographic information from the 100 Million Brazilian Cohort to mortality records and tuberculosis registries. They identified contacts of tuberculosis index patients diagnosed between January 1, 2004, and December 31, 2018, and monitored them until they were diagnosed with the disease themselves, died, or until December 31, 2018.

The study encompassed 420,854 household contacts of 137,131 tuberculosis index patients. Over the 15-year follow-up period (with a median of 4.4 years [interquartile range 1.9–7.6]), 8,953 contacts were diagnosed with tuberculosis. The tuberculosis incidence among contacts stood at 427.8 per 100,000 person-years at risk (95% CI 419.1–436.8), which was 16 times higher than the general population incidence of 26.2 (95% CI 26.1–26.3), indicating a prolonged elevated risk. Factors such as the index patient being of preschool age or having pulmonary tuberculosis were associated with increased tuberculosis incidence among contacts.

The persistent and heightened risk of tuberculosis among contacts underscores the urgent need for Brazil to systematically enhance contact tracing efforts and preventive treatment strategies. Such measures are crucial for achieving both national and international targets for tuberculosis elimination. 1

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References

  1. Pinto, P. F. P. S., Teixeira, C. S. S., Ichihara, M. Y., Rasella, D., Nery, J. S., Sena, S., Brickley, E. B., Barreto, M. L., Sanchez, M. N., & Pescarini, J. M. (2024). Incidence and risk factors of tuberculosis among 420 854 household contacts of patients with tuberculosis in the 100 Million Brazilian Cohort (2004–18): a cohort study. The Lancet Infectious Diseases, 24(1), 46–56. https://doi.org/10.1016/s1473-3099(23)00371-7

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