The cholera maps of John Snow have long captured health geographers and epidemiologists. Much has been written on this in recent years, most notably the superb book by Steven Johnson, Ghost Map. An upcoming article in the International Journal of Health Geographics provides perhaps the only research insight into the cholera event itself, using a detailed historical analysis to map the outbreak in space and time.
The study combines historical data to prepare a new dataset of cholera incidence and mortality over the outbreak period. This new data construction allows for inclusion of more cases than in the original Snow report, adding more insight into the space-time distribution of the cholera outbreak. The simple maps produced in this article lend confirmation to the sequencing and spatial distribution of cases in the vicinity of the Broad Street pump. The high mortality rates and absence of a space-time pattern indicates water-borne transmission rather than the “miasmic” theory that was prevalent of the time.
What is most innovative about this article is the willingness to revisit an event that has been taken as closed for 160 years, and to combine historical documentation, epidemiological methods, and spatial analysis. Most researchers would not think to re-analyse something like the 1854 cholera epidemic and would not feel that it could provide new insights into current health debates. However, given the extent to which we now know the environment is inter-related with human health we would be well-served by more articles such as this.