BACKGROUND: Tuberculosis (TB) continues to spread in South African prisons in particular, as prisons are over-capacitated
and have poor ventilation. The awaiting trial detainees are not screened on admission and are at high risk of
getting infected with TB.
RESULTS: We propose a compartmental model to describe the population dynamics of TB disease in prisons. Our
model considers the inflow of susceptible, exposed and TB infectives into the prison population. Removal of individuals
out of the prison population can be either by death or by being released from prison, as compared to a general
population in which removal is only by death. We describe conditions, including non-inflow of infectives into the
prison, which will ensure that TB can be eradicated from the prison population. The model is calibrated for the South
African prison system, by using data in existing literature. The model can be used to make quantitative projections
of TB prevalence and to measure the effect of interventions. Illustrative simulations in this regard are presented. The
model can be used for other prison populations too, if data is available to calculate the model parameters.
CONCLUSIONS: Various simulations generated with our model serve to illustrate how it can be utilized in making future
projections of the levels of prevalence of TB, and to quantify the effect of interventions such as screening, treatment
or reduction of transmission parameter values through improved living conditions for inmates. This makes it particularly
useful as there are various targets set by the World Health Organization and by governments, for reduction of
TB prevalence and ultimately its eradication. Towards eradication of TB from a prison system, the theorem on global
stability of the disease-free state is a useful indicator.