  We consider the problem of identifying an infection source based only on an
observed set of infected nodes in a network, assuming that the infection
process follows a Susceptible-Infected-Susceptible (SIS) model. We derive an
estimator based on estimating the most likely infection source associated with
the most likely infection path. Simulation results on regular trees suggest
that our estimator performs consistently better than the minimum distance
centrality based heuristic.
