Microscopic and macroscopic aspects of epidemics
We consider spatial epidemics, where the population is divided into clusters of size g @? 1. Microscopically, the interacting population is viewed as a stochastic cellular automaton; this induces macroscopic interactions between and within clusters. It is shown that for medium-sized epidemics the final size of the population depends on the initial dispersion of the infectives. We see for example that a sparse initial configuration is more severe than a clustered one, and give a way to quantify the magnitude of this effect.