Transmission of pathogens between infected and non-infected members of a population are critical in shaping the outcome of an epidemic. Despite major public hearth efforts to investigate infectious disease spread patterns, the fundamental mechanisms of transmission of most pathogens remain poorly understood. In particular, a critical gap persist in our understanding of the bridge between population-level and pathogen-level mechanisms. Fluid processes and physical laws at various scales, combined with biological processes, are key in filling this gap. In this talk, I will discuss how fluid dynamics and, in particular, multiphase, interfacial flows, and fluid fragmentation are critical in shaping pathogen footprints driving contact and transmission at various scales. I will present an overview of our approach, systematically combining theory and experiments, to elucidate transmission in the context of a range of public health systems.