The defeat of cholera

New epidemic diseases are always terrifying.1 Cholera arrived in Britain in 1832 when Britain didn’t have a medical-scientific infrastructure to cope. Favoured explanations for cholera were Miasma, (roughly, ‘bad air’), moral turpitude and God’s anger. Victorian Britain’s rationalists looked for evidence based explanations. After the third epidemic of 1854

Timeline for cholera

they dismissed miasma, God and other fanciful theories out of hand. This epidemic brought Snow’s theory of polluted water. His statistical analysis of the London outbreak identified precisely why the outbreak emerged where it did and why its victims were its victims. Cholera’s coup de grace came with the ground-breaking research of Louis Pasteur and Robert Koch. Their work plus engineer Joseph Bazalgette’s sewage systems eradicated cholera from first world countries.

King Cholera in a London slum

It was a commonplace belief that cholera struck poor areas because of the vile living conditions that existed in their neighbourhoods. The miasma theory fitted the narrative perfectly. Poor neighbourhoods stank making people feel ill just breathing and therefore they were ill because of bad air. John Snow lived in Soho, London, where the 1854 outbreak was virulent. His acute analytical mind dismissed the miasma theory when he saw people were dying in clusters. In brief everyone was breathing the same air but only some were dying.2

John Snow’s map of cholera in Soho, London

The miasma theory encouraged the belief that cholera victims were really victims of poor lifestyles. Therefore improving their lifestyle would prevent cholera.

Broadside issued by the New York Sanatory Committee during the cholera epidemic of 1849.

The dead hand of traditional knowledge3 denied Snow’s insight but an engineering solution was in hand with the creation of London’s sewage system. In 1858 London came to halt when the open sewer which was the River Thames erupted into virulent unpleasantness during a very hot summer. The miasma theory ironically came into its own. A gagging stench shut parliament and provoked action. Joseph Bazalgette, the chief engineer of the Metropolitan Board of Works, was financed for a stupendous public works project.4

London’s post- 1858 sewer system

Two great continental scientists Louis Pasteur and Robert Koch proved beyond doubt that cholera was transmitted by polluted water. Pasteur stroke of genius was to connect his work on beer to the wider problem of the transmission of disease. He developed the germ theory of transmission and Koch did the fundamental work establishing a new paradigm. Medical scientists could never again look beyond their work.

Louis Pasteur’s intellectual journey

The conquest of cholera was driven by non-medical analysis. Snow ‘knew’ that water caused cholera but was unable to demonstrate it: to prove it. The miasma theory took a long time to die but it’s final contribution was the investment in sewers following the Great Stink of 1858. Pasteur and Koch laid the intellectual foundations of modern medicine with their research. However cholera is still an ever present in the third world where the infrastructure of clean safe water is patchy. This was shown in Haiti in 2010-2 when UN provided peacekeepers inadvertently brought cholera with them from Nepal. Complacency is a killer where cholera is concerned.

1 Compare the Black Death, 1349, the Great Plague, 1665-6 and Ebola 2014-6.

2 …the Southwark and Vauxhall water company, your water is taken from the river directly downstream of a sewage outfall pipe. Snow’s great insight was to recognise that people who breathed the same air didn’t all die, and that S&V customers were dying at a rate 22 times higher than those of the Lambeth Water Company, whose intake was upstream of the outfall pipes.

3 Thomas Kuhn in 1962 described the way that science is dominated by paradigms which people build their careers on turning them into certainties. Attacking a paradigm is therefore more than just presenting a new thesis, if successful, it can end careers. Snow’s destruction of the miasma theory was resisted by many medical-scientists as it would overturn the basis of the transmission of disease rendering their knowledge obsolete. See

4 Amazingly Bazalgette’s work was opposed on the grounds that prevented the use of human waste as a resource regardless of the presumption that sewers saved lives.

There was outrage in 19th-century England when Bazalgette’s sewers wasted good excrement by transporting it into the sea. Excrement was a useful fertiliser, and suddenly London was making it useless by diluting it with drinking water. (Karl) Marx fumed at the monetary loss of so much good fertiliser.


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2 Responses to The defeat of cholera

  1. Chris Purnell says:

    A difficult subject which I tried to make accessible. Thank you very much.


  2. Ray emmett says:

    Another excellent piece, and thought provoking.


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