Thus, for the same model, R 0,N , R 0,J , R 0,C , R 0,9 , and R 0,e are all distinct. Although R 0,E = R 0,C in this case, this does not hold in general. Note that R 0,C and R 0,E produce the number of infected humans per infected human (or, equivalently, the number of infected mosquitoes per infected mosquito), but this is also not necessarily true in general. Figure 4 illustrates how these R 0 -like expressions vary with σ, when all other parameters are held constant.