Of the seven pathways, Pathway 1 exhibits the best fitness because the corresponding predicted infection risk distribution was qualitatively similar to that of the attack rates. As shown in Table 1, the infection risk was highest at Table 2 and decreased from Tables 1–6. As shown in Figure 3, the scenario with the best fitness is very similar to the baseline scenario, indicating that the index patient in this outbreak probably shed a viral load, L0, similar to those reported by the literature , with a ηm of 0.1415/genome copy .