This conference paper is a summary of the project 'Development of a theoretical basis for modeling disease processes in marine invertebrates'. The objective is to develop the theoretical basis to understand how epizootics are initiated and terminated in marine invertebrate populations and how this process is supported by transmission. The project combines experimental and modeling efforts. The model is informed using Dermo disease, caused by Perkinsus marinus, in Eastern oysters (Crassostrea virginica), as an experimental system. The model will be adaptable to all sessile or nearly sessile species whose movement is restricted to the small scale (e.g. bivalves, gastropods, sea urchins, corals) and to a range of hydrodynamic regimes from estuaries to lagoons to coral reef tracts.