The study of infectious diseases has undergone major changes since its infancy when it was largely a documentation of epidemics. It has now evolved into a dynamic phenomenon involving the ecology of the infectious agent, pathogenesis in the host, reservoirs and vetors, as well as the complex mechanisms concerned in the spread of infection and the extent to which this spread occurs. Rapid globalization has led to unprecedented interest in infectious diseases worldwide and their effect on complex population dynamics including migration, famine, fire, war, and terrorism. It is now essential for public health officials to understand the basic science behind infectious disease and, likewise, students studying ID must have a broader understanding of the implications of infectious disease in a public health context as well as clinical presentation and prevention. The clear demand for an integrated approach has led to the publication of this text.