Fig. 6.

Normalized forward sensitivity indices of ${\mathcal{R}}_0$ with respect to model parameters. Parameters are at the same values as in Table 2. A lower value of ${\mathcal{R}}_0$ is preferable since it enhances the possibility of disease eradication. Therefore, above all an increase in the parameters $\Lambda$, ${\beta }_1$, $\sigma$ and ${\lambda }_0$ must be prevented by all means, while an increase in $c_{m_s}$, a, ${\varphi }_s$, $\lambda$, ${\alpha }_s$, d and $M_0$ should instead be favored