An outbreak of swine flu is raising alarms from Mexico to New Zealand. But this isn’t the first epidemic to cause widespread concern. From the great influenza pandemic of 1918 to the much-hyped, but far less deadly bird flu outbreaks, we’re nothing if not prepared to worry about a global disease threat. So, how might this current outbreak compare to others throughout history? And how much should we really worry? We’re joined by Philip Alcabes, professor of urban public health at Hunter College of the City University of New York, and the author of Dread: How Fear and Fantasy Have Fueled Epidemics from the Black Death to Avian Flu.