A mathematical and numerical study of a SIR epidemic model with time delay, nonlinear incidence and treatment rates.

A novel nonlinear time-delayed susceptible-infected-recovered epidemic model with Beddington-DeAngelis-type incidence rate and saturated functional-type treatment rate is proposed and analyzed mathematically and numerically to control the spread of epidemic in the society. Analytical study of the model shows that it has two equilibrium points: disease-free equilibrium (DFE) and endemic equilibrium (EE). The stability of the model at DFE is discussed with the help of basic reproduction number, denoted by [Formula: see text], and it is shown that if the basic reproduction number [Formula: see text] is less than one, the DFE is locally asymptotically stable and unstable if [Formula: see text] is greater than one. The stability of the model at DFE for [Formula: see text] is analyzed using center manifold theory and Castillo-Chavez and Song theorem which reveals a forward bifurcation. We also derived the conditions for the stability and occurrence of Hopf bifurcation of the model at endemic equilibrium. Further, to illustrate the analytical results, the model is simulated numerically.