“…First of all, it worth mentioning that general references to the spatial spread of infectious diseases include [5,22,38,41,52,60]. The basic assumption of our treatment, namely that all epidemiological compartments are distributed over the whole spatial domain, is opposed to the alternative metapopulation approach that describes spatial structure through the relations between a number of wellidentified sub-populations or "patches" (cf., e.g., [3,6,7,18,35,57,58]). In fact, the description of spatial structure by explicitly specifying the mobilities between "patches" is typical for characterizing the behavior of humans, who usually do not "disperse" in response to environmental stimuli (at least not in the relatively short time scales involved in epidemiological modelling) but undertake directed travels, while a description through a convection-diffusion-reaction mechanism is more suitable for non-human infectious agents such as spores, insects, and bacteria that would disperse.…”