Figure 3

Events in the Swedish cattle population. The number of cattle affected per week by four event types in a simulation of VTEC O157 in the complete Swedish cattle population based on data reported to the Swedish Board of Agriculture during the period 2005-07-01 to 2013-12-31. The exit event implies slaughter, euthanasia or export, and defines the day an animal is excluded from the simulation. The enter event handles births and imports. The internal transfer event occurs on the day an animal changes age category from calf (0–119 days) to young stock (120–364 days) or young stock to adult (older than 364 days). The external transfer event occurs when animal moves from one holding to another. The dashed line is a loess smoother.