Modelling tuberculosis in South Africa

Tuberculosis ranks alongside HIV/AIDS as one of the deadliest infectious diseases in the world, killing 1.4 million people in 2015. The World Health Organization and the Stop TB Partnership set targets to achieve a 90% reduction in incidence and a 95% reduction in mortality from the 2015 values by 2035. We investigate the global dynamics of a compartmental system of ordinary differential equations that models tuberculosis. A more detailed model is then calibrated to the HIV negative TB endemic in South Africa and used to evaluate the 2035 reduction targets. Optimal care and control strategies for fixed budgets are also identified. Model projections for South Africa show the mortality targets can be met through combined interventions, however due to relapse and latent progression the incidence targets are unrealistic. To minimize incidence in 20 years, funding should be prioritized into linking drug susceptible cases (over multi-drug resistant cases) onto care.