The Broad Street Pump and Cholera, 1854 – John Snow and the Birth of Epidemiology

Science journalist Sharon Guynup wrote: 

“A new and terrible disease struck England in October 1831 and spread rapidly throughout the kingdom. Over the next two years, thousands died of this mysterious illness: someone healthy in the morning could be buried that evening. People lived in fear, closing doors and windows at night against ‘night air’.”

“Vibrio cholerae” is the bacterium causing the disease usually spread through water or food contaminated by human faeces: cholera. Known today for causing severe diarrhoea, it has claimed millions of lives over the centuries.

In 1854, when England experienced a cholera outbreak, many doctors believed unhealthy air or miasma (disease-bearing bad air) caused it. English physician John Snow believed it was not airborne.

Snow mapped cholera deaths and found unusual clusters of high mortality. About 500 people, for example, had died in ten days near a water source at Broad Street’s junction with Cambridge Street. Before mapping the cases, he urged officials to disable the Broad Street pump. Breaking its handle almost completely eliminated cholera in that area.

Snow, a major figure in epidemiology, acknowledged that the outbreak was already declining before the pump was disabled (possibly also because some residents had fled after the outbreak). 

Disabling the Broad Street pump nevertheless became a famous symbol of the dramatic effects that simple measures and visionary medical thinking can have on disease spread. Investigators later found that an old cesspit leaked faeces and cholera bacteria into the well. Snow compared deaths among customers of two water companies and found a 14-fold higher mortality risk among people supplied from the more contaminated source.

Snow’s work, particularly during London’s 1854 outbreak, laid the foundations of modern epidemiology. Documentaries and television programmes have covered it, although it has not directly inspired a big-budget Hollywood-style feature. A compelling 23-minute historical drama made in 2013 tells how epidemiology began with Snow.

Article image caption: Physician John Snow (1813-1858), a founding father of epidemiology. In 1854, he linked deaths to this water pump, establishing cholera as waterborne.

Historical figures mentioned: John Snow

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