A Simple Model for Multiple Epidemics
This Demonstration illustrates a very simple multiple epidemic model. At every iteration a random cell is chosen. The cell acquires the value (disease) of one of its four orthogonal neighbors unless it has previously assumed that value at a different time. Then, with a fixed probability, a random cell is chosen and it acquires a new value (disease) not yet found in the array. The model assumes that hosts can only be infected by one disease at a time, that being infected by another disease cures the original one, and that re-infection with the same disease multiple times is impossible.
This Demonstration is based on , which includes an analysis and discussion of the model. Boundary conditions are periodic.
Snapshot 1: a single disease spreading in a roughly circular manner
Snapshot 2: competition between two diseases
Snapshot 3: many diseases competing; disease emergence rate set very high
 K. Sneppen, A. Trusina, M. H. Jensen, and S. Bornholdt, "A Minimal Model for Multiple Epidemics and Immunity Spreading," PLoS ONE, 5(10), 2010 p. e13326.