Mapping Disease: John Snow and Cholera

In the 19th century, cholera was a deadly disease in Britain, with the 1866 London pandemic being the fourth and final one. John Snow, a physician, made a significant contribution in 1854 by linking cholera to contaminated drinking water, challenging the prevailing belief of disease transmission through 'bad air'. By mapping cholera cases in Soho, London, he identified a contaminated water pump as the source of the outbreak, leading to its containment. Snow's work, detailed in his essay "On the Mode of Communication of Cholera," laid the foundation for modern epidemiology and public health practices. Despite initial skepticism, his findings eventually influenced improvements in sanitation and public health policies. Snow's use of cartography and statistical analysis to visualize the correlation between water quality and cholera cases was groundbreaking. His work is commemorated in an exhibition at the Library, showcasing archival material related to public health history.