Configurations of plague: Spatial diagrams in early epidemiology

Diagrams are found at the heart of the modern history of epidemiology. They have been used to visualize specific spatio-temporal characteristics of epidemics, to draw out models of ecology as well as to conceptualize vectors with a scope ranging from microscopic pathogenic pathways to global transmission routes. Epidemiologists have long worked with spatial diagrams to visualize concepts of epidemics as arrangements of biological, environmental, historical as well as social factors. These diagrams observe, articulate and analyze an epidemic as configuration. Often, they provide a representation of the networks of relationships implied by an epidemic, rather than to offer conclusions about origin and causation. This article will look at two spatial diagrams of plague across a period in which epidemiologist’s persistence to their own diagrammatic way of reasoning stood in stark contrast to arguments provided about plague in the rising field of bacteriology and experimental medicine. The historical genealogy of epidemiologist’s workings with diagrams presented in this article challenges perceptions of epidemic diagrams as mere arguments of causality and blueprints for prevention. Instead the images of plague serve as examples to emphasize diagrammatic notions of uncertainty, crisis and invisibility.