Interventions targeting vector survival, such as insecticide spraying, increase the likelihood of immune pre-sensitisation through pre-exposure to vector saliva.

Shown are the equilibrium abundances in the ODE model of (a) susceptible (V_S; blue), exposed (V_E; purple) and infectious (V_I; red) vectors, and (b) infected hosts that are not pre-exposed (H_I; red) and that are pre-exposed (; pink) to vector saliva. Here, the x-axis is the daily rate of vector mortality imposed by vector control. Pre-sensitised and naïve infected hosts are assumed to have identical recovery rates (γ_H = γ_H′ = 60⁻¹ per day) and transmission probabilities (T_HV = T_H′V = T_VH = T_VH′ = 0.5). Note that the force of infection from vectors, rT_HVV_I, is proportional to the abundance of infectious vectors, and the rate of immune pre-sensitisation through vector saliva pre-exposure, rP_HV(V_S + V_E + (1 − T_HV)V_I), is roughly proportional to the abundance of susceptible vectors (notice that V_S is at least one order of magnitude larger than V_E or V_I).