Tuberculosis incidence among household contacts of individuals with symptomatic and asymptomatic tuberculosis: A historical cohort study in the Western Cape province of South Africa
7 affiliations
- 1South African Centre for Epidemiological Modelling and Analysis (SACEMA), Centre for Epidemic Response and Innovation (CERI), School for Data Science and Computational Thinking, Stellenbosch University, Stellenbosch, South Africa.
- 2Department of Paediatrics and Child Health, Desmond Tutu TB Centre, Stellenbosch University, Cape Town, South Africa.
- 3Department of Infectious Disease, Imperial College London, London, United Kingdom.
- 4Western Cape Department of Health and Wellness, Provincial Health Data Centre, Cape Town, South Africa.
- 5Centre for Integrated Data and Epidemiological Research, University of Cape Town, Cape Town, South Africa.
- 6Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom.
- 7Department of Human, Translational and Biological Medical Sciences, School of Medicine, University of Namibia, Windhoek, Namibia.
Abstract
Longitudinal, individual-level data describing long-term tuberculosis (TB) risk in high-burden communities are limited. We linked participants from the 2010 Zambia, South Africa Tuberculosis and AIDS Reduction (ZAMSTAR) prevalence survey to routine health records in the Western Cape Provincial Health Data Centre (PHDC) to estimate TB incidence of diagnosis over 11 years (to December 2020) among individuals without prevalent TB at enrolment. Cox proportional hazards models assessed predictors of TB diagnosis, including sex, age, HIV status, and household exposure to symptomatic or asymptomatic TB. Of 30,017 participants enrolled in the ZAMSTAR prevalence survey, 15,887 (52.9%) were linked to the PHDC, including 15,471 without prevalent TB at enrolment. Of the 15,471 individuals, 1,819 (11.8%) developed incident TB over the subsequent 11 years. TB incidence declined from 1,614 per 100,000 person-years in 2011–1,302 per 100,000 person-years in 2019. Over follow-up, individuals who had been exposed to symptomatic TB within their household had the highest cumulative probability of TB diagnosis (13%; 95% CI: 7.7–18%). In a multivariable Cox model adjusted for sex and HIV status, individuals living with a household contact with symptomatic TB had a higher hazard of TB incidence than those from unexposed households (aHR 1.53, 95% CI: 1.09–2.13); the hazard of incident TB among those exposed to asymptomatic TB was not significantly elevated (aHR 1.12, 95% CI: 0.67–1.87). In sensitivity analyses restricting follow-up to two and three years, hazard ratios were higher among individuals living with a symptomatic household contact (two years: 1.82 (95% CI: 0.97–3.41) and three years: 1.73 (95% CI: 0.98–3.10)). This long-term linked cohort demonstrates sustained TB incidence in this high-burden community. Incomplete linkage of individuals to the PHDC highlights the need for improving data collection in research studies and national patient identification systems to support long-term cohort analyses.
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BibTeX
@article{brown2026tuberculosis,
title = {{Tuberculosis incidence among household contacts of individuals with symptomatic and asymptomatic tuberculosis: A historical cohort study in the Western Cape province of South Africa}},
author = {Lauren R Brown and James A Seddon and Christopher Kelly and Mariette Smith and Peter Godfrey-Faussett and Rory Dunbar and Andrew Boulle and Georgia A Roussos and Mareli Claassens and Cari van Schalkwyk},
journal = {PLOS Global Public Health},
year = {2026},
month = oct,
doi = {10.1371/journal.pgph.0006550},
url = {https://journals.plos.org/globalpublichealth/article?id=10.1371/journal.pgph.0006550},
note = {CC BY},
}
RIS
TY - JOUR
TI - Tuberculosis incidence among household contacts of individuals with symptomatic and asymptomatic tuberculosis: A historical cohort study in the Western Cape province of South Africa
AU - Lauren R Brown
AU - James A Seddon
AU - Christopher Kelly
AU - Mariette Smith
AU - Peter Godfrey-Faussett
AU - Rory Dunbar
AU - Andrew Boulle
AU - Georgia A Roussos
AU - Mareli Claassens
AU - Cari van Schalkwyk
PY - 2026
DA - 2026/10/29
JO - PLOS Global Public Health
DO - 10.1371/journal.pgph.0006550
UR - https://journals.plos.org/globalpublichealth/article?id=10.1371/journal.pgph.0006550
AB - Longitudinal, individual-level data describing long-term tuberculosis (TB) risk in high-burden communities are limited. We linked participants from the 2010 Zambia, South Africa Tuberculosis and AIDS Reduction (ZAMSTAR) prevalence survey to routine health records in the Western Cape Provincial Health Data Centre (PHDC) to estimate TB incidence of diagnosis over 11 years (to December 2020) among individuals without prevalent TB at enrolment. Cox proportional hazards models assessed predictors of TB diagnosis, including sex, age, HIV status, and household exposure to symptomatic or asymptomatic TB. Of 30,017 participants enrolled in the ZAMSTAR prevalence survey, 15,887 (52.9%) were linked to the PHDC, including 15,471 without prevalent TB at enrolment. Of the 15,471 individuals, 1,819 (11.8%) developed incident TB over the subsequent 11 years. TB incidence declined from 1,614 per 100,000 person-years in 2011–1,302 per 100,000 person-years in 2019. Over follow-up, individuals who had been exposed to symptomatic TB within their household had the highest cumulative probability of TB diagnosis (13%; 95% CI: 7.7–18%). In a multivariable Cox model adjusted for sex and HIV status, individuals living with a household contact with symptomatic TB had a higher hazard of TB incidence than those from unexposed households (aHR 1.53, 95% CI: 1.09–2.13); the hazard of incident TB among those exposed to asymptomatic TB was not significantly elevated (aHR 1.12, 95% CI: 0.67–1.87). In sensitivity analyses restricting follow-up to two and three years, hazard ratios were higher among individuals living with a symptomatic household contact (two years: 1.82 (95% CI: 0.97–3.41) and three years: 1.73 (95% CI: 0.98–3.10)). This long-term linked cohort demonstrates sustained TB incidence in this high-burden community. Incomplete linkage of individuals to the PHDC highlights the need for improving data collection in research studies and national patient identification systems to support long-term cohort analyses.
SN - 2767-3375
ER -