Simulating the spread of the BSE disease: a cellular automata approach

The rules of evolution applied in the cellular automata approach may correspond to the propagation of the mad cow disease. In a computer simulation of the BSE disease's spread both inherited and infectious mechanisms are accounted for. The initial population of items is randomly distributed on a two-dimensional square lattice, Nx × Ny = 1000 × 1000, with a fraction of 1 percent the items already infected. Alternatively, faulty prions may spontaneously develop during the simulation with a very small frequency. Our results indicate a critical probability, pc, of BSE transmission, so that for p below the threshold the population recovers. For p > pc the disease is launched in the population with a dynamic equilibrium between the healthy and infected fractions of the population. The threshold is very sensitive to spatial clustering of the population and the detailed rules for the disease's onset, evolution and propagation.