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Diagram of a map of London, showcasing clusters of cholera cases represented by rectangles.
Epidemiological map by John Snow showing clusters of cholera cases in the London epidemic (1854).

Epidemiology emerges as a field led by John Snow, who will become known as the "father" of the field.

1854

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Epidemiological map by John Snow showing clusters of cholera cases in the London epidemic (1854).

Starting in 1854, British anesthesiologist John Snow conducts investigations into an outbreak of cholera in London, tracing the infections back to contaminated water pumps. The field of epidemiology initially develops to track the problems of purifying air, water, and other natural resources, but soon becomes focused on tracking disease as it moves through communities.