How pathogens invade the body, how new infectious diseases are recognized, how epidemics arise and how new treatments are developed are discussed in this Howard Hughes Medical Institute1999 Holiday Lectures on Science Seriess. In "Outwitting Bacteria ’s Wily Ways" B. Brett Finlay discusses molecular mechanisms, the virulence factor and potential therapies for bacterias E. coli, salmonella and Listeria. Next, Donald E. Gamen analyzes how pathogens, the environment and human behavior cause epi demics by tracking hantavirus, smallpox and the myxoma virus. Study guide available. Closed captioned.