Traditional approaches for understanding disease have focused on epidemiology, or the study of incidence and distribution of disease among humans and their control. But there is increasing documentation of disease spilling over from wildlife to human populations through zoonotic diseases, and we have now begun to acknowledge that parasites are a common and integral part of our ecosystem. To understand infectious and zoonotic disease threats to humans, we need to understand the ecology and evolution of hosts and pathogen in wildlife areas. This course will focus on problems related to the ecological and evolutionary processes that drive the transmission of pathogens between hosts. We will try to understand the impact of the disease on host populations, and the factors that cause the emergence of an infectious disease. We will explore the important link between planetary health and human health.