Rocky Mountain spotted fever (RMSF) is a severe, often-fatal tick-borne disease that affects both humans and dogs. It occurs in several distinct ecological cycles, with very different epidemiologic characteristics between locations. In this talk, we will discuss these cycles, including the emergence of epidemic RMSF in northern Mexico and differences in the eco-epidemiology between western and eastern United States. The complex relationship between tick vectors, domestic and wildlife hosts, climate change, and human behaviors will be examined. Participants will gain understanding of the risk factors for RMSF emergence in different locations in North America, and develop an improved ability to detect and prevent infection in humans and dogs.