Open AccessResistance to Mycobacterium tuberculosis infection among highly TB exposed South African gold miners
Author(s) -
Violet Chihota,
Thobani Ntshiqa,
Pholo Maenetje,
Raoul Mansukhani,
Kavindhran Velen,
Thomas R. Hawn,
Robert S. Wallis,
Alison D. Grant,
Gavin Churchyard,
Katherine Fielding
Publication year - 2022
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0265036
Subject(s) - interquartile range , tuberculosis , medicine , epidemiology , odds ratio , confidence interval , mycobacterium tuberculosis , quantiferon , demography , immunology , latent tuberculosis , pathology , sociology
Background Despite high exposure to Mycobacterium tuberculosis , a small proportion of South African goldminers resist TB infection. We determined, among long-service gold miners i) the proportion who were TB uninfected and ii) epidemiological factors associated with being uninfected. Methods We enrolled HIV-negative gold miners aged 33–60 years with ≥15 years’ service and no history of TB or silicosis. Miners were defined as TB uninfected if i) QuantiFERON-TB Gold Plus (QFT-Plus) negative or ii) in a stricter definition, QFT-Plus-negative and zero-response on TST and as resisters if they were of Black/African ethnicity and negative on both tests. Logistic regression was used to identify epidemiological factors associated with being TB uninfected. Results Of 307 participants with a QFT-Plus result, median age was 48 years (interquartile range [IQR] 44–53), median time working underground was 24 years (IQR 18–28), 303 (99%) were male and 91 (30%) were QFT-Plus-negative. The odds of being TB uninfected was 52% lower for unskilled workers (adjusted odds ratio [aOR] 0.48; 95% confidence interval [CI] 0.27–0.85; p = 0.013). Among 281 participants of Black/African ethnicity, 71 (25%) were QFT-Plus negative. Miners with a BMI ≥30 were less likely to be TB uninfected (OR 0.38; 95% CI 0.18–0.80). Using the stricter definition, 44.3% (136/307) of all miners were classified as either TB uninfected (35; 26%) or infected, (101; 74%) and the associations remained similar. Among Black/African miners; 123 were classified as either TB uninfected (23; 19%) or infected (100; 81%) using the stricter definition. No epidemiological factors for being TB uninfected were identified. Conclusions Despite high cumulative exposure, a small proportion of miners appear to be resistant to TB infection and are without distinguishing epidemiological characteristics.