Gomes, M. G. M.Margheri, A.Medley, G. F.Rebelo, C.2009-10-082009-10-0820052005-10Gomes MG, Margheri A, Medley GF, Rebelo C.(2005)."Dynamical behaviour of epidemiological models with sub-optimal immunity and nonlinear incidence".Journal of mathematical biology1432-1416http://hdl.handle.net/10400.7/51In this paper we analyze the dynamics of two families of epidemiological models which correspond to transitions from the SIR (susceptible-infectious-resistant) to the SIS (susceptible-infectious-susceptible) frameworks. In these models we assume that the force of infection is a nonlinear function of density of infectious individuals, I. Conditions for the existence of backwards bifurcations, oscillations and Bogdanov-Takens points are givenengModels, BiologicalEpidemiology/statistics & numerical dataNonlinear DynamicsModels, Immunologicaljournal article2009-10-08