Fig. 6.

Surface plots of co-infected individuals $L_{H_1}$ (first column), $L_{H_2}$ (second column), $I_{H_1}$ (third column) and $I_{H_2}$ (fourth column) with respect to (a) ${\nu }_1$ and ${\nu }_3$, (b) $h_3$ and ${\nu }_3$, (c) l and m, and (d) ${\alpha }_3$ and r. Other parameters are at the same values as in Table 1