Distribution of infected holdings. (Left) Stochastic disease spread modelling of verotoxigenic Escherichia coli O157:H7 (VTEC O157) in the complete Swedish cattle population. The four left figures show the proportion of 1000 simulated trajectories that each holding had at least one infected animal at 1 October 2011, 1 January 2012, 1 April 2012, and 1 July 2012. The right figure shows a comparison of individual cattle VTEC O157 status from samples collected at abattoirs 2011–2012, where the circles represent the origin of each sampled animal. To reduce over-plotting, jitter was added to the coordinates. Letters denote regions: (a) Falköping, (b) Halland, (c) Skåne, (d) Öland and (e) Gotland.