  The widely used susceptible-infected-recovered (S-I-R) epidemic model assumes
a uniform, well-mixed population, and incorporation of spatial heterogeneities
remains a major challenge. Understanding failures of the mixing assumption is
important for designing effective disease mitigation approaches. We combine a
run-and-tumble self-propelled active matter system with an S-I-R model to
capture the effects of spatial disorder. Working in the motility-induced phase
separation regime both with and without quenched disorder, we find two epidemic
regimes. For low transmissibility, quenched disorder lowers the frequency of
epidemics and increases their average duration. For high transmissibility, the
epidemic spreads as a front and the epidemic curves are less sensitive to
quenched disorder; however, within this regime it is possible for quenched
disorder to enhance the contagion by creating regions of higher particle
densities. We discuss how this system could be realized using artificial
swimmers with mobile optical traps operated on a feedback loop.
