eprintid: 431 rev_number: 4 eprint_status: archive userid: 5 dir: disk0/00/00/04/31 datestamp: 2007-04-19 lastmod: 2013-07-01 14:05:16 status_changed: 2013-07-01 14:05:16 type: techreport metadata_visibility: show item_issues_count: 0 creators_name: Franceschetti, Andrea creators_name: Pugliese, Andrea title: Threshold behaviour of SIR epidemic model with age structure and immigration ispublished: unpub subjects: TU full_text_status: public abstract: We consider a SIR age-structured model with immigration of infectives in all epidemiological compartments; the population is supposed in demographic equilibrium between below-replacement fertility and immigration; the spread of the infection occurs through a general age-dependent kernel. We analyse the equations for steady states; because of immigration of infectives a steady state with a positive density of infectives always exists; however, a quasi-threshold theorem is proved, in the sense that, below the threshold, the density of infectives is close to 0, while it is away from 0, above the threshold; furthermore, conditions that guarantee uniqueness of steady states are obtained. Finally, we present some numerical examples, inspired to the Italian demographic situation, that illustrate the threshold-like behaviour, and other features of the stationary solutions and of the transient. date: 2007-02 date_type: published institution: University of Trento department: matematica refereed: FALSE referencetext: [1] H. Amann. On the number of solutions of nonlinear equations in ordered Banach spaces. Journal of Functional Analysis, 11:346–384, 1972. [2] R.M. Anderson and R.M. May. Vaccination against rubella and measles: quantitative investigations of different policies. J. 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