Just before cholera broke out in Soho, a child living at number 40 Broad Street had been taken ill with cholera symptoms, and its soiled “nappies” had been steeped in water that was subsequently tipped into a leaking cesspool situated only three feet from the Broad Street well.®!

Snow took a sample of water from the pump. Checking it microscopically, he thought he observed the white “rice water” particles seen in the stools of cholera victims. Convinced that he had found the source of the disease, he went to the Board of Guardians of St. James’s Parish, who, though reluctant to believe him, did agree to remove the handle from the Broad Street pump as an experiment. Once the handle was removed new cases of cholera stopped appearing.

People in the area were aware of undrained cesspits beneath old houses, and Snow guessed that these pits were draining into wells and contaminating the water in that area.

Snow was aware that severe watery diarrhea was an early manifestation of cholera, and he thought that the outbreak must be due to “miasmas” originat- ing in water contaminated by sewage.

he first great epidemiological study of disease was a study of the cholera outbreaks in London, conducted by a surgeon who was struck by the large num- bers of deaths in Soho, the area of London where he lived.