Controlling the spread of infectious diseases in large populations is an important societal challenge, and one which has been highlighted by current events. Mathematically, the problem is best captured as a certain class of reaction-diffusion processes (referred to as contagion processes) over appropriate synthesized interaction networks. Agent-based models have been successfully used in the recent past to study such contagion processes. Our work revolves around the development of Loimos, a highly scalable parallel code written in Charm++ which uses agent-based modeling to simulate disease spread over large, realistic, co-evolving networks of interaction.