Infectious diseases have changed the world in the past (e.g., bubonic plague, 1918 flu pandemic), in the present (AIDS pandemic) and certainly will impact our world in the future. What are the origins of infectious diseases? How do environmental factors influence their spread? What, if anything, can we do to reduce the impacts of these diseases? After we familiarize ourselves with the structure and function of the vertebrate immune system, we will explore the biology of twelve major infectious diseases and their impacts on society. The course will consist of readings, lectures, discussions and student presentations. We will compare and contrast perspectives from popular science magazines and peer-reviewed journals.