John Snow’s 19th century dot-map (from the series introduction) is representative of a shift in the public management of infectious diseases towards measuring density of confirmed cases within a geographic region. This practice is referred to in epidemiology as spatial clustering and as “hotspots” more colloquially. Today’s outbreak investigations use visual representations of disease spread as a standard practice. Johns Hopkins’ COVID-19 tracker was one such communicative tool for showing the intensification of an outbreak across space and time. The visual becomes representative of a more than normal number of confirmed cases in spatial and temporal balance, to allow the viewer to identify what we reference as hotspots. In what follows, I will examine the utility of the term hotspots through an investigation into the public discussion of the current United States measles outbreaks (2024—) put in contrast with the localized practice of frontline healthcare professionals in South Florida. I will show how hotspots have meaning beyond their colloquial uptake as clear and accurate representations of who is getting sick. (read more...)