摘要：This paper relies on the concept of next generation matrix defined ad hoc for a new
proposed extended SEIR model referred to as -model to study its stability. The model includes successive stages of infectious subpopulations, each one acting
at the exposed subpopulation of the next infectious stage in a cascade global disposal
where each infectious population acts as the exposed subpopulation of the next infectious
stage. The model also has internal delays which characterize the time intervals of
the coupling of the susceptible dynamics with the infectious populations of the various cascade infectious stages. Since the susceptible subpopulation is common, and then
unique, to all the infectious stages, its coupled dynamic action on each of those stages
is modeled with an increasing delay as the infectious stage index increases from 1 to . The physical interpretation of the model is that the dynamics of the disease exhibits
different stages in which the infectivity and the mortality rates vary as the individual
numbers go through the process of recovery, each stage with a characteristic average
time.
