In 1854, a cholera outbreak erupted in the Soho area of London. At the time, it was believed that cholera was spread by ‘miasma’ or a poisonous form of ‘bad air’ that was emitted from rotting organic matter.

Physician John Snow, whose practice was in Soho, was skeptical of the accepted theory, and instead had a hunch that cholera was spread via contaminated water from nearby sewage and cesspools.

The doctor began going door to door talking to local residents, and made a map of people who fell ill. He used information from local hospital and public records and asked residents if they had drunk water from the public water pump on Broad Street. It turns out: they all had.

Snow wrote:

“Within 250 yards of the spot where Cambridge Street joins Broad Street there were upwards of 500 fatal attacks of cholera in 10 days… As soon as I became acquainted with the situation and extent of this irruption (sic) of cholera, I suspected some contamination of the water of the much-frequented street-pump in Broad Street.”

Snow convinced local officials to take the handle off the pump, and soon after the outbreak came to an end. The doctor presented his views on cholera and its spread to the Medical Society of London, but they were rejected by the medical establishment. His ‘germ’ theory of disease would not become accepted until 1866.

In 1883, the German physician Robert Koch isolated the bacterium Vibrio cholerae, and determined that cholera is spread through unsanitary water or food supply sources, supporting Snow’s theory from 20 years earlier.

Sadely, Snow never lived to see his ideas be accepted however, the physician had a stroke at his practice in June 1858, and died 6 days later at the age of 45.

It is speculated that Snow’s extensive and prolonged self-experimentation with anesthetics (ether and chloroform) over a 9-year period led to renal failure, swollen fingers and early death from stroke.

Today, John Snow is considered one of the founders of modern epidemiology.

Don’t shoot the messenger. Science is never settled.