Rapidly mutating pathogens may be able to persist in the population and reach an endemic equilibrium by escaping acquired immunity of hosts. For such diseases, multiple biological, environmental and population level mechanisms determine epidemic dynamics. In previous studies we focused on the impact of the population distribution and mobility network . In this work we go one step further and study this impact with multiple competing strains.
We consider a susceptible-infected-recovered-susceptible model on a metapopulation system connected with a network of mobility flows. We use a mechanistic stochastic model to systematically explore different levels of spatial disaggregation, mobility flows and strain competition/cooperation, reconstructing the phase space of pathogens persistence and the dynamics out of the equilibrium.
Our results show that the increase in the average duration of immunity reduces the chance of persistence until extinction is certain above a threshold value. Such critical parameter, however, is crucially affected by the traveling probability, being larger for intermediate levels of mobility coupling, and by the competition between strains. Even more, competition at the early stages of the epidemic produces long lasting effects that alter the persistence in the equilibrium even if one of the strains fades out at those early stages.
The dynamical regimes observed are very diversified and present oscillations and metastable states. Topological heterogeneities leave their signature on the spatial dynamics, where subpopulation connectivity affects recurrence of epidemic waves, spreading velocity and chance to be infected. The present work uncovers the crucial role of hosts’ space structure on the ecological dynamics of interacting rapidly mutating pathogens, opening the path for further studies on disease ecology in presence of a complex and heterogeneous environment.