A High-Gain Observer for Stage-Structured Susceptible-Infectious Epidemic Model with Linear Incidence Rate

Epidemiological models play a vital role in under-standing the spread and severity of a pandemic or epidemic caused by an infectious disease in a host population. The mathematical modeling of infectious diseases in the form of compartmental models are often employed in studying the probable outbreak growth. In this paper, we study the problem of state estimation for a stage-structured SI model with two classes of infected which can be considered as a simplified modelling approach to chronic diseases with progressive severity, as is the case with AIDS. Towards this end, a high-gain observer design based on system state augmentation approach is proposed to estimate the states of the SI model. Simulation results are reported with some comparisons to the standard high-gain observer.