Many network phenomena are well modeled as spreads of epidemics throughout the network. Prominent examples include the propagation of worms (e.g., Code Red) and viruses, and, more generally, faults. In this talk, we apply epidemic spreading models to these phenomena paying particular attention to the following two questions.

l        What makes an epidemic virulent?

l        How does network topology affect the virulence of an epidemic?

In the context of a worm, virulence relates to the time required for it to spread. And in the context of the propagation of faults (cascading failures), virulence relates to the time until faults die out. We will illustrate how simple fluid and Markov epidemic spreading models can shed light to the above questions for both worms and the propagation of faults.

This work was done with A. Ganesh, W. Gong, L. Massoulie, C. Zou