Tuberculosis control in South African gold mines: mathematical modeling of a trial of community-wide isoniazid preventive therapy.
Bottom Line: A recent major cluster randomized trial of screening, active disease treatment, and mass isoniazid preventive therapy for 9 months during 2006-2011 among South African gold miners showed reduced individual-level tuberculosis incidence but no detectable population-level impact.We found the following: 1) The model suggests that a small proportion of latent infections among human immunodeficiency virus-positive people were cured, which could have been a key factor explaining the lack of detectable population-level impact. 2) The optimized implementation increased impact by only 10%. 3) Implementing additional interventions individually and in combination led to up to 30% and 75% reductions, respectively, in tuberculosis incidence after 10 years.Tuberculosis control requires a combination prevention approach, including health systems strengthening to minimize treatment delay, improving diagnostics, increased antiretroviral treatment coverage, and effective preventive treatment regimens.
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Mentions: We developed an age-structured deterministic compartmental model (Figure 2) describing M. tuberculosis transmission dynamics for each intervention cluster and its control, matching identically, except for the intervention. The model considers culture-positive tuberculosis (“active disease”), extending previous work (7, 8). Cluster populations comprise 4 age strata (<30, 30–39, 40–49, and ≥50 years) because of age-dependent population mobility and 2 human immunodeficiency virus (HIV) strata (HIV-positive or HIV-negative). Model output is aggregated into 2 age strata (<40 and ≥40 years) or all ages, given insufficient data to further stratify the incidence and prevalence. Clusters are considered independent, because little movement occurred between intervention and control arms.Figure 2.