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| Interactions among multiple infectious agents are increasingly recognized as a fundamental issue in the understanding of key questions in public health, regarding pathogen emergence, maintenance, and evolution. The full description of host-multipathogen systems is however challenged by the multiplicity of factors affecting the interaction dynamics and the resulting competition that may occur at different scales, from the within-host scale to the spatial structure and mobility of the host population.
Here we study the dynamics of two competing pathogens in a structured host population and assess the impact of both epidemiological parameters and the mobility patterns of the hosts population. We model the spatial structure of the population in terms of a metapopulation network and consider the most general case where the two pathogens can have different infectious duration and offer different levels of cross-immunity one to another. Via both mechanistic numerical simulations and a theoretical analysis we find that the model presents a very rich behavior with different dynamical regimes. We were able to fully characterize the regions of the parameters space where the two pathogens coexist at both systemic and single population level.
In this scenario we also characterize, via a very simple analytical reasoning, the effects of the degree of cross-immunity between pathogens finding that for high hosts' mobility only two states are possible: one in which only the fastest pathogen survives and one in which the both diseases reach a similar fraction of the system.
Finally, the present work sheds some light on the complex interactions between multiple infections spreading on the same population allowing for a deeper understanding of real world scenarios like the seasonal coexistence of different influenza strains. |
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