Remarks on epidemic spreading in scale-free networks

Abstract

Classical epidemiological theory has been developed by mainly focusing on the temporal dynamics of the different population compartments, basing on the assumption that individuals are homogeneously mixing. Important results obtained with basic SIS models on scale-free networks have instead given emphasis to the role of heterogeneity in the spreading process. Here, by means of two instrumental examples, we make the point that the interplay between the infection process and the network topology is more important than credited. The first example considers non-vital infectious processes characterized by nonlinear force of infection which causes backward bifurcations. The second example deals with standard infective mechanisms in processes where vital dynamics (births and deaths) cannot be disregarded. In both cases we find evidence that it is too simplistic to claim that scale-free networks are the most efficient media for the spreading of whatever infection. © 2009 Springer-Verlag Berlin Heidelberg.