  Active Brownian disks moving in two dimensions that exchange information
about their internal state stochastically are chosen to model epidemic spread
in a self-propelled population of agents under the
susceptible-infected-recovered-susceptible (SIRS) framework. The state of
infection of an agent, or disk, governs its self-propulsion speed;
consequently, the activity of the agents in the system varies in time. Two
different protocols (one-to-one and one-to-many) are considered for the
transmission of disease from the infected to susceptible populations. The
effectiveness of the two protocols are practically identical at high values of
the infection transmission rate. The one-to-many protocol, however, outperforms
the one-to-one protocol at lower values of the infection transmission rate.
Salient features of the macroscopic SIRS model are revisited, and compared to
predictions from the agent-based model. Lastly, the motility induced phase
separation in a population of such agents with a fluctuating fraction of active
disks is found to be well-described by theories governing phase separation in a
mixture of active and passive particles with a constant fraction of passive
disks.
