Locally self-organized quasicritical percolation in a multiple-disease model.

Diseases emerge, persist, and vanish in an ongoing battle for available hosts. Hosts, on the other hand, defend themselves by developing immunity that limits the ability of pathogens to reinfect them. We here explore a multidisease system with emphasis on mutual exclusion. We demonstrate that such a system develops toward a steady state, where the spread of individual diseases self-organizes to a state close to that of critical percolation, without any global control mechanism or separation of time scale. For a broad range of introduction rates of new diseases, the likelihood of transmitting diseases remains approximately constant.