Probability of persistence and within-herd proportion of infected animals in secondarily infected farms. The scenario with 1% of the farms initially infected, uniformly sampled, and with medium levels of within-herd prevalence is shown. (A) Probability of persistence of within-farm infection 5 years after infection set up (corresponding to the introduction of the first animal) as a function of the number of infected animals purchased during the same period. (B) Within-herd prevalence at five years of infection duration according to the number of infected animals purchased by the farm over these five years. Each box contains values between the first and the third quartiles. Horizontal lines outside boxes correspond to the first quartile – 1.5x interquartile range and the third quartile + 1.5x interquartile range. Red dots correspond to mean values and thick horizontal lines to medians. For each range of the number of infected animals purchased, top values correspond to the number (black) and the proportion (grey) of incident farms in which infection was still persistent five years after the pathogen introduction over the whole set of runs. As a given farm can be counted several times, the number of distinct farms used to build the box plot is also provided (blue).