  Rapidly mutating pathogens may be able to persist in the population and reach
an endemic equilibrium by escaping hosts' acquired immunity. For such diseases,
multiple biological, environmental and population-level mechanisms determine
the dynamics of the outbreak, including pathogen's epidemiological traits (e.g.
transmissibility, infectious period and duration of immunity), seasonality,
interaction with other circulating strains and hosts' mixing and spatial
fragmentation. Here, we study a susceptible-infected-recovered-susceptible
model on a metapopulation where individuals are distributed in subpopulations
connected via a network of mobility flows. Through extensive numerical
simulations, we explore the phase space of pathogen's persistence and map the
dynamical regimes of the pathogen following emergence. Our results show that
spatial fragmentation and mobility play a key role in the persistence of the
disease whose maximum is reached at intermediate mobility values. We describe
the occurrence of different phenomena including local extinction and emergence
of epidemic waves, and assess the conditions for large scale spreading.
Findings are highlighted in reference to previous works and to real scenarios.
Our work uncovers the crucial role of hosts' mobility on the ecological
dynamics of rapidly mutating pathogens, opening the path for further studies on
disease ecology in the presence of a complex and heterogeneous environment.
