John Snow (Cholera outbreak investigation)

John Snow was a British doctor in the 19th century who investigated a cholera outbreak in London. He famously mapped cases of cholera around the city and discovered that many infected people lived near a particular public water pump on Broad Street. By removing the pump handle, he effectively halted the outbreak, illustrating the link between contaminated water and disease. His work laid the groundwork for modern epidemiology and public health, emphasizing the importance of clean water and sanitation in preventing illness.