Fig. 4

The density of infected sheep holdings following the simulated introduction of sheep scab into Lancashire. The darker the shading, the higher the density of sheep holdings which were infected in a 1-year period across 60 model simulations (a, b) and across 4 model simulations (c, d). Sheep holdings were considered to be contiguous when located ≤ 2 km apart (a, b) or ≤ 4 km apart (c, d). Sheep movements were included in the model simulations in b and d but not in the simulations for a and c