Global properties of a delayed SIR epidemic model with multiple parallel infectious stages.

In this paper, we study the global properties of an SIR epidemic model with distributed delays, where there are several parallel infective stages, and some of the infected cells are detected and treated, which others remain undetected and untreated. The model is analyzed by determining a basic reproduction number R0, and by using Lyapunov functionals, we prove that the infection-free equilibrium E0 of system (3) is globally asymptotically attractive when R0 ≤ 1, and that the unique infected equilibrium E* of system (3) exists and it is globally asymptotically attractive when R0 > 1.