How did John Snow stop cholera?

How John Snow Silenced the Broad Street Cholera Outbreak

In mid-19th century London, cholera was widely believed to spread through foul air, or "miasma." However, physician John Snow suspected a vastly different culprit: contaminated water. When a devastating outbreak struck the Soho district in 1854, Snow set out to test his theory using a remarkably simple yet revolutionary method.

He meticulously mapped every reported case of cholera across the neighborhood. As the visual pattern took shape, a clear center emerged—the overwhelming majority of victims lived within walking distance of the public water pump on Broad Street (now Broadwick Street). Snow's investigation revealed that raw sewage was leaking into the well supplying that specific pump.

Armed with his findings, Snow persuaded the local authorities to take immediate action. On September 8, 1854, officials removed the handle from the Broad Street pump, disabling access to the tainted water. Almost overnight, the surge of new infections collapsed, bringing the deadly epidemic under control. Snow's spatial analysis not only saved countless lives in Soho, but it also laid the foundation for modern epidemiology.