Contact- and index case characteristics associated with IGRA positivity in close contacts of pulmonary tuberculosis in Brazil: a multicenter cohort

Identifying Mycobacterium tuberculosis infection in close contacts is central to TB control, yet evidence on factors associated with interferon-gamma release assay (IGRA) positivity in high-burden settings is limited. This study assessed contact- and index case characteristics associated with IGRA positivity in the multicenter RePORT-Brazil cohort. Close contacts were defined as individuals with four hours per week of exposure to a tuberculosis case. IGRA testing was performed at baseline and six months, and associations were estimated using mixed-effects regression models accounting for clustering by index case. Among 1,234 close contacts, 534 (43.2%) tested IGRA positive during follow-up. Higher odds of positivity were associated with older age (adjusted odds ratio [aOR] per 10-year: 1.19; 95%CI: 1.08–1.32), non-white race (aOR: 1.81; 95%CI: 1.22–2.70), lower neutrophil count (aOR per 1,000 cells/µL: 0.91; 95%CI: 0.83–0.99) and current tobacco use (aOR: 1.77; 95%CI: 1.15–2.73). Index case characteristics included cavitation on chest radiography (aOR: 1.81; 95%CI: 1.26–2.59), history of TB (aOR: 0.54; 95%CI: 0.34–0.88), and non-white race (aOR: 1.60; 95%CI: 1.02–2.48). Neither contact nor index case BMI was associated with IGRA positivity. These findings identify clinical and social factors associated with IGRA positivity among close contacts, refining the risk profile of this high-priority group.

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Journal
Scientific Reports
Published
2026-09-16
DOI
https://doi.org/10.1038/s41598-026-71240-8
Primary Topic
Tuberculosis Research and Epidemiology
Type
article
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article

Contact- and index case characteristics associated with IGRA positivity in close contacts of pulmonary tuberculosis in Brazil: a multicenter cohort

Jaquelane Silva, Aline Benjamin, Adriano Gomes-Silva, Jamile G. de Oliveira et al.
Scientific Reports
Tuberculosis Research and Epidemiology
article

Contact- and index case characteristics associated with IGRA positivity in close contacts of pulmonary tuberculosis in Brazil: a multicenter cohort

Jaquelane Silva, Aline Benjamin, Adriano Gomes-Silva, Jamile G. de Oliveira, Bruno B. Andrade, Sayonara M. Viana, Allyson Guimarães Costa, Saulo R N Santos, Pedro Brito, Michael S. Rocha, Anna Cristina Calçada Carvalho, Isabella B. B. Ferreira, André Luiz Bezerra, Alice M S Andrade, Alexandra B. Souza, Quézia Medeiros de Oliveira, Betina Durovni, Marcelo Cordeiro‐Santos, Mayla Mello, Jéssica Rebouças-Silva, Cody Staats, Vanessa Nascimento, Adriana da Silva Rezende Moreira, Elisângela C. Silva, Rodrigo C. Menezes, Maria Cristina Lourenço, Felipe Ridolfi, Marina C. Figueiredo, Solange Cavalcante, Megan Turner, Timothy R. Sterling, Juan M. Cubillos-Angulo, Flavia M. Sant’Anna, André Ramos, José R. Lapa e Silva, Renata Spener-Gomes, Mariana Araújo-Pereira, João Marine Neto, Afrânio L. Kritski, Valeria C. Rolla, Betânia M. F. Nogueira, Francine P. Ignácio
article en

Abstract

Identifying Mycobacterium tuberculosis infection in close contacts is central to TB control, yet evidence on factors associated with interferon-gamma release assay (IGRA) positivity in high-burden settings is limited. This study assessed contact- and index case characteristics associated with IGRA positivity in the multicenter RePORT-Brazil cohort. Close contacts were defined as individuals with four hours per week of exposure to a tuberculosis case. IGRA testing was performed at baseline and six months, and associations were estimated using mixed-effects regression models accounting for clustering by index case. Among 1,234 close contacts, 534 (43.2%) tested IGRA positive during follow-up. Higher odds of positivity were associated with older age (adjusted odds ratio [aOR] per 10-year: 1.19; 95%CI: 1.08–1.32), non-white race (aOR: 1.81; 95%CI: 1.22–2.70), lower neutrophil count (aOR per 1,000 cells/µL: 0.91; 95%CI: 0.83–0.99) and current tobacco use (aOR: 1.77; 95%CI: 1.15–2.73). Index case characteristics included cavitation on chest radiography (aOR: 1.81; 95%CI: 1.26–2.59), history of TB (aOR: 0.54; 95%CI: 0.34–0.88), and non-white race (aOR: 1.60; 95%CI: 1.02–2.48). Neither contact nor index case BMI was associated with IGRA positivity. These findings identify clinical and social factors associated with IGRA positivity among close contacts, refining the risk profile of this high-priority group.

Scientific Reports
Universidade Federal do Rio de Janeiro (BR), Instituto Federal da Bahia (BR), Escola Bahiana de Medicina e Saúde Pública (BR), Vanderbilt University (US), Fundação de Medicina Tropical (BR), Associação Saúde da Família (BR), Fundo Brasil (BR), Universidade Nilton Lins (BR), Instituto Evandro Chagas (BR), Secretaria Municipal de Saúde (BR), Fundação Oswaldo Cruz (BR), Universidade Federal do Amazonas (BR)
Conselho Nacional de Desenvolvimento Científico e Tecnológico, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Ministério da Saúde, Fundação Oswaldo Cruz, National Institute of Allergy and Infectious Diseases
Good health and well-being
Openalex Percentile: Top 11%
Tuberculosis Research and Epidemiology
DOIOpen Access PDFOpenAlex
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