Travelling wave solutions in a non-local and time-delayed reaction–diffusion model

This paper is to study the existence of travelling wave solutions in a non-local and time-delayed reaction–diffusion malaria model proposed by Lou and Zhao (2011, A reaction–diffusion malaria model with incubation period in the vector population. J. Math. Biol., 62, 543–568). We first analyse the positivity and invariance of solutions for the corresponding Cauchy problem in an unbounded domain. Then, according to the basic reproduction ratio R0 which serves as a threshold that predicts whether epidemics will spread, we show that there exist travelling wave solutions connecting the two steady states: the disease-free steady state and the endemic steady state if R0>1, and there do not exist travelling wave solutions connecting the disease-free steady state itself if R0<1. This explores how a malaria infected state invades into the previously uninfected state in the spatial domain. Numerical simulation is provided to show that the travelling wave solutions can be non-monotone.