Before the advent of the germ theory of disease in the 1870s, quarantine provided one of the few effective means to prevent or alleviate epidemics. The Lazaretto quarantine station in Philadelphia illustrates the history of quarantine both before and after the discovery of pathogenic microbes. With us to explore the history of 18th and 19th century quarantine in Philadelphia, and what it meant for public health, is David Barnes. David teaches the history of medicine and public health at the University of Pennsylvania, where he is an Associate Professor of History and Sociology of Science. David received a BA in history from Yale in 1984 and a Ph.D. in history from the University of California, Berkeley in 1992. His books include The Making of a Social Disease: Tuberculosis in Nineteenth-Century France (University of California Press, 1995), The Great Stink of Paris and the Nineteenth-Century Struggle against Filth and Germs (Johns Hopkins University Press, 2006), and Lazaretto: How Philadelphia Used an Unpopular Quarantine Based on Disputed Science to Accommodate Immigrants and Prevent Epidemics (Johns Hopkins University Press, 2023).