Peter Haggett's research over the last thirty years has focused on mapping and modelling the paths by which epidemics spread through human communities. This led to his 1998 inaugural lectures for a new series, the Clarendon Lectures in Geography and Environmental Studies, the result of which is this book. In it, Haggett presents an accessible, concise, and well illustrated account of how environmental and geographical concepts can be used to enhance our knowledge of the origins and progress of epidemics, and sometimes to slow or even halt their spread.