Prevalence of latent tuberculosis infection among gold miners in South Africa

Abstract

Setting: South African gold mines.

Objective: To determine the prevalence of latent tuberculosis infection (LTBI) and risk factors for a positive tuberculin skin test (TST) among gold miners.

Design: Cross-sectional survey. Human immunodeficiency virus (HIV) status was determined by self-report and medical records. TST positivity was defined by the mirror method to estimate the prevalence of LTBI, and by the US Centers for Disease Control and Prevention definitions to explore risk factors at the individual level.

Results: Among 429 participants (105/130 subjects aged <30 years, 324/390 > or = 30 years), the estimated prevalence of LTBI was 89%; 45.5% of HIV-positive participants had a zero TST response compared to respectively 13% and 13.5% in the HIV-negative and status unknown participants. In participants with TST > 0, there was no significant difference between size of response by HIV status: the mean (standard deviation) widths for HIV-positive, HIV-negative and HIV status unknown were respectively 11.84 (2.75), 12.03 (2.75) and 12.52 mm (3.04) (analysis of variance P = 0.28). Factors independently associated with a TST < 10 mm were positive HIV status (aOR 0.41, 95%CI 0.17-0.96) and not working underground (aOR 0.25, 95%CI 0.09-0.71).

Conclusions: The prevalence of LTBI is very high in gold miners in South Africa. HIV-infected individuals are more likely to have a negative TST, but HIV infection does not affect the size of TST response.