Just Read the Map

John Snow (1813-1858) was one of the first anaesthetists – he even chloroformed Queen Victoria! – but today he is famous for his investigation of the 1854 Broad Street cholera outbreak in Soho, London. By mapping the cases of cholera he was able to link transmission of the illness to contaminated water consumed from the Broad Street pump. This hammered a nail in the coffin of the “miasma” theory of cholera transmission (sorry, Egerton!), and heralded the birth of the new science of epidemiology.

snow map cholera

Map 1. Published by C.F. Cheffins, Lith, Southhampton Buildings, London, England, 1854 in Snow, John. On the Mode of Communication of Cholera, 2nd Ed, John Churchill, New Burlington Street, London, England, 1855.

As John Snow himself said:

On proceeding to the spot, I found that nearly all the deaths had taken place within a short distance of the [Broad Street] pump. There were only ten deaths in houses situated decidedly nearer to another street-pump. In five of these cases the families of the deceased persons informed me that they always sent to the pump in Broad Street, as they preferred the water to that of the pumps which were nearer. In three other cases, the deceased were children who went to school near the pump in Broad Street… With regard to the deaths occurring in the locality belonging to the pump, there were 61 instances in which I was informed that the deceased persons used to drink the pump water from Broad Street, either constantly or occasionally… The result of the inquiry, then, is, that there has been no particular outbreak or prevalence of cholera in this part of London except among the persons who were in the habit of drinking the water of the above-mentioned pump well.

John Snow, “The Cholera Near Golden Square, and at Deptford”, Medical Times and Gazette 1854; 9: 321-22

Steven Berlin Johnson has written a truly enthralling book called”The Ghost Map” about John Snow and the Broad Street outbreak, highlighting the importance of sanitation and public heath in the evolution of the modern city, as well as the fascinating characters involved. I recommend reading it. Here he is talking about it at TED:

Chris is an Intensivist and ECMO specialist at The Alfred ICU, where he is Deputy Director (Education). He is a Clinical Adjunct Associate Professor at Monash University, the Lead for the  Clinician Educator Incubator programme, and a CICM First Part Examiner.

He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives. He was one of the founders of the FOAM movement (Free Open-Access Medical education) has been recognised for his contributions to education with awards from ANZICS, ANZAHPE, and ACEM.

His one great achievement is being the father of three amazing children.

On Bluesky, he is @precordialthump.bsky.social and on the site that Elon has screwed up, he is @precordialthump.

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