John Snow

John Snow was an English physician, who was a leader in the adoption of anesthesia and is considered one of the fathers of modern epidemiology. His success in tracing the source of a cholera outbreak in Soho, London, in 1854 inspired fundamental changes in the city’s water and waste systems which led to similar changes in other cities, and a significant improvement in general public health around the world.

Snow was first to identify the connection between water quality and cholera.

Snow was born on March 15th 1813 in York, England. From a young age, he demonstrated an aptitude for mathematics and in 1827, when he was 14, he obtained a medical apprenticeship with William Hardcastle in Newcastle-upon-Tyne. He encountered a cholera epidemic for the first time in Killingworth, a coal-mining village, in 1832. Snow treated many victims of the disease and gained a lot of experience.

He was admitted as a member of the Royal College of Surgeons of England in 1838, graduated from the University of London in December 1844 and was admitted to the Royal College of Physicians in 1850. In 1850 he was also one of the founding members of the Epidemiological Society of London, formed in response to the cholera outbreak of 1849.

Snow was a skeptic of the then-dominant miasma theory that stated that diseases such as cholera were caused by pollution or a noxious form of "bad air". The germ theory of disease had not yet been developed, so Snow did not understand the mechanism by which the disease was transmitted. He first publicised his theory in an 1849 essay, On the Mode of Communication of Cholera, followed by a more detailed treatise in 1855 incorporating the results of his investigation of the role of the water supply in the Soho epidemic of 1854.

London was a booming city in the mid 19th century and the negative effects of public health were not yet fully understood.

By talking to local residents, he identified the source of the outbreak as the public water pump on Broad Street (now Broadwick Street). Although Snow's chemical and microscope examination of a water sample from the pump did not conclusively prove its danger, his studies of the pattern of the disease were convincing enough to persuade the local council to disable the well pump by removing its handle. This action has been commonly credited as ending the outbreak, but Snow observed that the epidemic may have already been in rapid decline.

Snow later used a dot map to illustrate the cluster of cholera cases around the pump. He also used statistics to illustrate the connection between the quality of the water source and cholera cases. He showed that the Southwark and Vauxhall Waterworks Company was taking water from sewage-polluted sections of the Thames and delivering the water to homes, leading to an increased incidence of cholera. Snow's study was a major event in the history of public health and geography. It is regarded as the founding event of the science of epidemiology.

It was common for livestock and people to live cohabit within Britain's cities - a recipe for public health problems.

Snow was one of the first physicians to study and calculate dosages for the use of ether and chloroform as surgical anaesthetics, allowing patients to undergo surgical and obstetric procedures without the distress and pain they would otherwise experience. He designed the apparatus to safely administer ether to the patients and also designed a mask to administer chloroform. He even personally administered chloroform to Queen Victoria when she gave birth to the last two of her nine children, Leopold in 1853 and Beatrice in 1857.

In June 1858 Snow suffered a stroke while working in his London office. He never recovered, dying on June 16th. He was buried in Brompton Cemetery.

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