Fig. 2.

Normalized trajectories for human $\overline{X}\left(\tau \right),$ and mosquito $\overline{Z}\left(\tau \right)$ infectiousness with an applied, model IRS at time $\tau =10$. The application period, which has duration $\overline{\tau }=18$ (18 mosquito lifetimes, maybe a bit more than a half year) is highlighted in both panels. The top figure shows the long-lasting effects of IRS in a low-transmission ($R_0=12.5$) environment, which recovers slowly post-intervention. Below, the same IRS has a similar effect, but recovers rapidly post-intervention in the medium-high transmission environment, $R_0=75$. Mosquito lifetimes are diminished by an introduced prefactor κ set to preserve $R_0^I=0.5$ during the intervention. Other parameters are set as before and more details are in the text.