Prevalence and risk factors for latent tuberculosis infection among household contacts of index cases in two South African provinces: analysis of baseline data from a cluster-randomised trial

MacPherson, P. et al. (2020) Prevalence and risk factors for latent tuberculosis infection among household contacts of index cases in two South African provinces: analysis of baseline data from a cluster-randomised trial. PLoS ONE, 15(3), e0230376. (doi: 10.1371/journal.pone.0230376) (PMID:32182274) (PMCID:PMC7077873)

Abstract

Introduction: Household contacts of patients with active pulmonary tuberculosis (TB) often have latent TB infection, and are at risk of progression to disease. We set out to investigate whether index TB case HIV status was linked to a higher probability of latent TB infection among household contacts. Materials and methods: Data were collected prospectively from participants in the intervention arm of a household cluster-randomised trial in two South Africa provinces (Mangaung, Free State, and Capricorn, Limpopo). In intervention group households, TB contacts underwent HIV testing and tuberculin skin testing (TST). TST induration was estimated at two cut-offs (≥5mm, ≥10mm). Multilevel Bayesian regression models estimated posterior distributions of the percentage of household contacts with TST induration ≥5mm and ≥10mm by age group, and compared the odds of latent TB infection by key risk factors including HIV status index case age and study province. Results: A total of 2,985 household contacts of 924 index cases were assessed, with most 2,725 (91.3%) undergoing TST. HIV prevalence in household contacts was 14% and 10% in Mangaung and Capricorn respectively. Overall, 16.8% (458/2,725) had TST induration of ≥5mm and 13.1% (359/2,725) ≥10mm. In Mangaung, children aged 0-4 years had a high TST positivity prevalence compared to their peers in Capricorn (22.0% vs. 7.6%, and 20.5% vs. 2.3%, using TST thresholds of ≥5mm and ≥10mm respectively). Compared to contacts from Capricorn, household contacts living in Mangaung were more likely to have TST induration ≥5mm (odds ratio [OR]: 3.08, 95% credibility interval [CI]: 2.13-4.58) and ≥10mm (OR: 4.52, 95% CI: 3.03-6.97). There was a 90% and 92% posterior probability that the odds of TST induration ≥5mm (OR: 0.79, 95% CI: 0.56-1.14) and ≥10mm (OR: 0.77, 95% CI: 0.53-1.10) respectively were lower in household contacts of HIV-positive compared to HIV-negative index cases. Conclusions: High TST induration positivity, especially among young children and people living in Mangaung indicates considerable TB transmission despite high antiretroviral therapy coverage. Household contact of HIV-positive index TB cases were less likely to have evidence of latent TB infection than contacts of HIV-negative index cases.

• Item Type: Articles
• Additional Information: This study was funded by the South African Medical Research Council and the UK MRC Newton Fund (SAMRC grant number: 96783). The South African Government funded all laboratory investigations. Support and approval was obtained from the Provincial Departments of Health of the Limpopo and Free State Provinces. PM is supported by Wellcome (grant number: WT089673).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: MacPherson, Professor Peter
• Authors: MacPherson, P., Lebina, L., Motsomi, K., Bosch, Z., Milovanovic, M., Ratsela, A., Lala, S., Variava, E., Golub, J. E., Webb, E. L., and Martinson, N. A.
• College/School: College of Medical Veterinary and Life Sciences > School of Health & Wellbeing > Public Health
• Journal Name: PLoS ONE
• Publisher: Public Library of Science
• ISSN: 1932-6203
• ISSN (Online): 1932-6203
• Copyright Holders: Copyright © 2020 MacPherson et al.
• First Published: First published in PLoS ONE 15(3):e0230376
• Publisher Policy: Reproduced under a Creative Commons licence