This article examines Mexico City's typhus epidemic of 1915–16 and makes three central claims. First, the federal response to the outbreak, while laudable in light of the grim circumstances, was disjointed and excessively bureaucratic. Second, the epidemic drew out long-standing stereotypes of poor indigenous populations, leading people to make misguided linkages between the high incidence of typhus within those populations and their supposed moral or intellectual shortcomings. Third, the typhus epidemic prompted fundamental reforms to the nation's public health system. As a delegate to the constitutional convention of 1917, the nation's chief public health officer, general and doctor José María Rodríguez, successfully promoted his vision of a “sanitary dictatorship” that would operate according to strict authoritarian principles for the sake of efficiency. The epidemic thus shaped not only the human experience in that moment but also the course of revolutionary political reform in the years to come.