The neglected burden of tuberculosis disease among health workers: a decade-long cohort study in South Africa

BACKGROUND: Health workers (HWs) in resource-limited settings are at high-risk of exposure to tuberculosis (TB) at work. The aim of this study was to estimate the rate of TB disease among HWs in the Free State Province of South Africa between 2002 and 2012 and to compare demographic and clinical characteristics between HWs and the general population with TB. This study also explores the effect of occupational variables on risk of TB among HWs. METHODS: Probabilistic record linkage was utilized to identify HWs who were also registered as TB patients. This historical prospective cohort study calculated incidence rate ratios (IRR) for TB disease among HWs in Free State from 2002 to 2012. Generalized linear mixed-effects regression was used to model the association between sex, race, facility type, occupation, duration of employment, and the rate of TB. RESULTS: There were 2677 cases of TB diagnosed among HWs from 2002 to 2012 and 1280 cases were expected. The overall TB incidence rate in HWs during the study period was 1496·32 per 100,000 compared to an incidence rate of 719·37 per 100,000 in the general population during the same time period. IRR ranged from 1·14 in 2012 to 3·12 in 2005. HWs who were male, black, coloured and employed less than 20 years had higher risk of TB. Facility type and occupation were not associated with increased risk of TB when adjusted for other covariates. CONCLUSION: HWs in South Africa have higher rates of TB than the general population. Improved infection prevention and control measures are necessary in all high-burden TB healthcare settings. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12879-017-2659-3) contains supplementary material, which is available to authorized users.