title: Incidence of occupational latent tuberculosis infection in South African healthcare workers.
abstract: The test-specific incidence of latent tuberculosis infection (LTBI) in healthcare workers from sub-Saharan Africa is unknown. 505 healthcare workers from South Africa were screened at baseline, and after 12 months, with a questionnaire, the tuberculin skin test (TST), and two T-cell assays (T-SPOT.TB and QuantiFERON-TB Gold-In-Tube). Test-specific conversion rates were calculated. The prevalence of presumed LTBI at baseline was 84, 69 and 62% using the TST, QuantiFERON-TB Gold-In-Tube and T-SPOT.TB, respectively. The annual test-specific conversion rate, depending on the cut-off point used, was as follows: TST 38%; QuantiFERON-TB Gold-In-Tube 13-22%; and T-SPOT.TB 18-22%. Annual reversion rates were 4, 7 and 16%, respectively. The annual TST conversion rate was significantly higher than that derived from published local community-based data (IRR 3.53, 95% CI 1.81-6.88). Factors associated with conversion (any test) included healthcare sector of employment, counselling of tuberculosis patients, and a baseline positive TST (for T-SPOT.TB). The annual rate of tuberculosis infection in South African healthcare workers was very high, irrespective of the testing method used, and may be explained by occupational exposure, as the rate was considerably higher than non-healthcare workers from the same community. Collectively, these data support the need for implementation of tuberculosis-specific infection control measures in Africa.
authors.affiliation: Lung Infection and Immunity Unit, Dept of Medicine, University of Cape Town, Cape Town, South Africa Centre for Environmental and Occupational Health Research, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa.
authors.forename: Shahieda
authors.initials: S
authors.lastname: Adams
authors.affiliation: Centre for Environmental and Occupational Health Research, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa.
authors.forename: Rodney
authors.initials: R
authors.lastname: Ehrlich
authors.affiliation: Dept of Environmental and Occupational Studies, Faculty of Applied Sciences, Cape Peninsula University of Technology, Cape Town, South Africa.
authors.forename: Roslynn
authors.initials: R
authors.lastname: Baatjies
authors.affiliation: Lung Infection and Immunity Unit, Dept of Medicine, University of Cape Town, Cape Town, South Africa.
authors.forename: Richard N
authors.initials: RN
authors.lastname: van Zyl-Smit
authors.affiliation: Radiology Dept, New Somerset Hospital, Cape Town, South Africa.
authors.forename: Qonita
authors.initials: Q
authors.lastname: Said-Hartley
authors.affiliation: Centre for TB Research Innovation, University of Cape Town Lung Institute, Cape Town, South Africa.
authors.forename: Rodney
authors.initials: R
authors.lastname: Dawson
authors.affiliation: Lung Infection and Immunity Unit, Dept of Medicine, University of Cape Town, Cape Town, South Africa.
authors.forename: Keertan
authors.initials: K
authors.lastname: Dheda
mesh_terms: D000328:Adult; D005260:Female; D006282:Health Personnel / Q000706:statistics & numerical data*; D006801:Humans; D015994:Incidence; D059425:Interferon-gamma Release Tests; D055985:Latent Tuberculosis / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000453:epidemiology*; D015995:Prevalence; D011446:Prospective Studies; D013019:South Africa; D014374:Tuberculin Test