John Snow

Although many may recognise the name as a Game of Thrones character, John Snow (15th March 1813 – 16th June 1858) was a British physician, and arguably the father of epidemiology. His role in the suppression of the 1854 outbreak of Cholera in London is perhaps his most recognised achievement, however he was also cofounder of the Epidemiological Society of London and one of the first physicians to optimise doses of anaesthesia for surgical procedures. 

In the August of 1854, Mrs Lewis of 40 Broad St washed her poorly child’s nappy and disposed of the contaminated water in the cesspool outside her house. A few days later, her young, poorly child died. 56 cases of Cholera were also reported within a 250 yard radius around the Broad St water pump. 

The Broad St water pump was known for its ‘purity’, a reason why many of the neighbouring streets used the water pump as well as the residents of Broad St. For example, the owners of a local factory (the Eley brothers) used the pump for their water source, and would send one flagon a day to their mother in Hempstead. Two barrels of the water from the Broad St pump were kept and used in the factory. Several workers in the Eley brothers factory died from Cholera, and in Hempstead there was only one recorded death from Cholera at the time- the Eley brothers mother. 

Snow did not accept the ‘miasma’ theory (bad air theory) of which many believed was the cause of Cholera. He microscopically examined the water from the Broad St pump and other local water pumps, noting that although the Broad St water looked the cleanest the microscopic examination revealed ‘a good deal of organic matter and oval animacules’. 

He also collected information on what water the victims had drunk before their death, plotting the data upon a map and noting that most of the affected individuals collected their water from the Broad St pump. 

The investigations by John Snow resulted in the Board of Governors and Directors of the Poor removing the handle of the pump. By the end of September the outlook was all but over, with a death toll of 616. Although action was taken, many disagreed with his ‘germ’ theory of disease until the 1860’s.

Later excavations revealed a cesspool drain had become blocked, and was leaking into the Broad St pump just 1 metre away. 

The actions of John Snow not only potentially saved many lives, but established the field of Epidemiology which holds great importance to public health today.