A SIMPLE-MODEL OF RECURRENT EPIDEMICS

A cellular automaton conceived as a simple model of disease spreading is investigated. We show that the steady-state of the model is describ ed by a spatial organization of the infectious individuals on fronts a nd undamped temporal oscillations in the number of infectious individu als. This behaviour is observed both for a deterministic and a stochas tic input of susceptible individuals, hence showing that recurrent epi demic behaviour can be persistent without any external forcing. The si mplicity of the model suggests that such spatio-temporal behaviour can be obtained from nothing, but a direct transmission mechanism between nearest neighbors provided some mechanism for the introduction of new susceptible individuals, e.g., loss of immunity is present.