Ricardo Castillo-Neyra, PhD, DVM, MSPH is an instructor in the Department of Biostatistics, Epidemiology, & Informatics in Perelman School of Medicine, and the scientific director of the Zoonotic Disease Research Lab (Penn and Universidad Peruana Cayetano Heredia in Peru). He studies the eco-epidemiology of tropical diseases. His current research uses canine rabies as a system model to understand how the social and spatial features of cities influence the emergence and persistence of infectious diseases. Dog rabies threatens human health in the Americas and is expanding in some regions. Why can’t we get rid of the oldest known zoonotic disease? Ricardo conducts community-based studies in southern Peru to answer this question. He also conducts studies in Guatemala.