AN SEI MODEL WITH DENSITY-DEPENDENT DEMOGRAPHICS AND EPIDEMIOLOGY

Two compartmental models for the dynamics of an infectious disease in a wild-animal population ale analysed. The models feature density-depe ndent birth, death, and contact rates, and pseudovertical disease tran smission. For the SI model it is shown that up to four steady states m ay exist, depending on the parameter values, and that one of these sta tes is globally stable. For the SEI model four equivalent steady state s exist, but periodic solutions are now possible for some parameter va lues.