Fraction of cows and std of time to disease as a function of noise level. Fraction of cows reaching high shedding as a function of the noise level σ in the model with a wide β distribution (black line), and the standard deviation of the time it takes to reach an ill state (gray dashed line). The simulations were run on a scale of 100 time units in arbitrary units. One can see that for a wide range of σ values (two orders), the fraction of cows getting ill is constant and low and the standard deviation of the time to reach sickness is high. Thus the model is not limited to a precise value of σ or β to reproduce the observed dynamics.