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Home / The International Journal of Tuberculosis and Lung Disease, Volume 19, Number 6

High incidence of latent tuberculous infection among South African health workers: an urgent call for action

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SETTING: In South Africa, health care workers (HCWs) are at two-fold greater risk of acquiring tuberculosis (TB) disease than the general population. Few studies have evaluated the risk of incident tuberculous infection.

OBJECTIVE: To determine the incidence and risk factors for latent tuberculous infection (LTBI) among HCWs and to compare the results of the interferon-gamma release assay (IGRA) with those of the tuberculin skin test (TST).

DESIGN: HCWs, including medical students, underwent a TST and human immunodeficiency virus (HIV) and IGRA testing at baseline and 12 months, and IGRA at 6 months. The participants kept 12-month TB exposure logs.

RESULTS: Among 199 participants (150 [76%] females, median age 31 years [range 20–61]), incident LTBI was documented using IGRA in 25/97 (26%; incident rate 29 cases/100 person-years [py], 95%CI 20–44) and using TST in 25/93 (27%; incident rate 29 cases/100 py, 95%CI 19–42). Agreement between TST and IGRA was poor (44.8%, κ = 0.23). Higher annual exposure to TB cases was reported among persons with LTBI than in those who were persistently IGRA-negative (81 cases, 95%CI 61–102 vs. 50 cases, 95%CI 43–57, P < 0.01).

CONCLUSION: The high LTBI incidence and the association of incident LTBI with annual TB caseload among HCWs indicate that more effective TB infection control should be implemented in South African health care facilities.

Keywords: IGRA; TB infection control; TST; occupational health

Document Type: Research Article

Affiliations: 1: Wits Reproductive Health and HIV Research Unit, University of the Witwatersrand, Johannesburg, South Africa; The Aurum Institute, Parktown, Johannesburg, South Africa; School of Public Health, University of the Witwatersrand, Johannesburg, South Africa 2: Department of Molecular Diagnostics, National Health Laboratory Service and University of the Witwatersrand, Johannesburg, South Africa 3: Wits Reproductive Health and HIV Research Unit, University of the Witwatersrand, Johannesburg, South Africa 4: Infectious Diseases, Department of Epidemiology, University of North Carolina, Chapel Hill, North Carolina, USA

Publication date: 01 June 2015

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  • The International Journal of Tuberculosis and Lung Disease (IJTLD) is for clinical research and epidemiological studies on lung health, including articles on TB, TB-HIV and respiratory diseases such as COVID-19, asthma, COPD, child lung health and the hazards of tobacco and air pollution. Individuals and institutes can subscribe to the IJTLD online or in print – simply email us at [email protected] for details.

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