“…In recent years there have been many studies on SIS and other types of disease transmission models in spatially and/or temporally varying environments; see [31,32,33,34,48,49,50,51,95,96,120,133,134,135,136,154]. For instance, to study the effect of the movement of exposed individuals on disease outbreaks, the following SEIRS (susceptible-exposed-infected-recovered-susceptible) epidemic reaction-diffusion model was considered in [143]: Here we divide the individuals into four different compartments: susceptible (S), exposed (E), infectious (I), recovered (immune by vaccination, R).…”