Infection dynamics of
spread over one year in four simulated scenarios. Absence of inter-herd transmission (A, black, not visible as all the results are null), transmission by cattle trade only (B, blue), transmission by airborne dispersion (C, cyan), and presence of both transmission routes (D, red). The subdivision of scenario D based on the identified cause of herd infection is also represented (due to animal trade—orange; by airborne dispersion—green). (A) Distribution of the total number of predicted incident herds. (B) Dynamics of incidence (mean over 100 runs). Shaded regions for the subdivisions of scenario D represent 95% empirical confidence intervals. (C) Median proportion of intra-herd shedders and 80th percentile (represented by shaded area) for all the scenarios. Inset figure shows the proportion of shedders (median and 80th percentile) for subdivisions of scenario D. Median and percentiles are calculated for runs where herds experienced infection (sample sizes are 16 733 for D, 13 814 for C and 3617 for B).