Global dynamics of autonomous and nonautonomous SI epidemic models with nonlinear incidence rate and feedback controls

This paper discusses autonomous and nonautonomous epidemic models with nonlinear incidence rate of saturated mass action and feedback controls. The global asymptotic stability of disease-free equilibrium and the endemic equilibrium of the autonomous system is established using suitable Lyapunov functional. It is shown that by choosing suitable values of feedback control variables, one can make the disease endemic or extinct as time evolves. Moreover, the effect of coefficient of inhibition on the persistence of disease is also discussed. We discuss the permanence, existence, uniqueness and asymptotic stability of an almost periodic solution of the model. The analytical results obtained in this paper are illustrated with the help of numerical examples.