Cholera - History

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Cholera - History

• Dr Andrew Hayward - Lecturer - Epidemiology and
  Public Health University of Nottingham- UK

WHO Cholera Fact sheet
John Snow web-site - UCLA
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Dr Andrew Hayward

• I am an epidemiologist who is
  particularly interested in
  the epidemiology of infectious disease. Its
  easy to forget how diseases like cholera used to
  be so important even in rich countries. The
  disease provides a unique insight into the power
  of a public health approach.

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Learning Objectives

• To understand the historical background to John
  Snows work on cholera.
• To understand how John Snow used epidemiology to
  determine the cause of cholera.
• To understand how this led to disease prevention
  on a massive scale.

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Performance Objectives

• To be able to find and use information related to
  cholera and other water-born diseases.

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• Vibrio cholerae.
• Often mild symptoms
• Severe disease in around 5
• Profuse watery diarrhoea, vomiting, and leg
  cramps. Rapid dehydration and shock.
• Without treatment, death can occur within hours.

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Pandemics of cholera

• Cholera pandemics spread around the globe
• Most have started in the Indian Subcontinent
• The most recent started in 1961

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• Cholera sufferers are dehydrated and often have
  deep sunken eyes.
• Cholera pandemics caused great fear and changed
  history. Cholera tramples the victor and the
  vanquished both.

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Beliefs about the causes of cholera

• Supernatural causes
• The wrath of God
• Astrological causes
• Miasma - or bad air
• Contagion

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Miasma

• Miasma - bad or malodorous air as a cause of
  disease.
• Pleasant or strong smelling agents (e.g.
  Camphor, herbs, or smoke) were thought to be
  protective.

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Miasma

• Public health efforts concentrated on finding the
  source of bad smells.

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Protection against cholera

• Many believed that alcohol would protect against
  cholera.

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A case of true cholera

• There was some perception that disease could be
  spread by contact with the patient or contact
  with their clothes (fomites). Fumigation of
  premises was thought to be valuable.

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Cholera epidemics in England

• 1831-1832 - 22,000 deaths
• 1848-1849 - 52,000 deaths
• 1853-1854 - John Snows work
• It was against this background of confusion that
  John Snow carried out his work.

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John Snow mapped cases of cholera to help give
him clues about the cause.
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Broad Street Pump

• Mapping of cases led John snow to suspect water
  from the Broad street pump as a cause of cholera.
  
• He found that those who were affected had drunk
  water from the pump.

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Broad Street Pump

• He identified that a child at number 40 Broad
  street had been ill with cholera and that sewage
  had probably contaminated the well.

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Removal of the pump handle.

• John Snow recommended the pump should not be used
  and that its handle should be removed.

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The outbreak subsided.

• After the handle was removed the outbreak
  subsided.
• Despite this there was scepticism about his
  findings.

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The Grand Experiment

• Two water companies supplied one area. In 1949
  both got water direct from the Thames in London.
  In 1954 the Lambeth Company moved its source
  upstream to cleaner water.

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• Comparison of risks of dying from cholera
• Southwark and Vauxhall water company 70 per
  10,000 (London Source)
• Lambeth water company 5 per 10,000 - (Source from
  upstream of London)

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• 1831-1832 - 22,000 deaths
• 1848-1849 - 52,000 deaths
• 1853-1854 - John Snows work
• Massive public concern and sanitary reform
  followed.
• Final epidemic was in 1866 there were only around
  2,200 deaths.

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Vibrio Cholera

• The organism that causes cholera was discovered
  25 years after John Snows death by Robert Koch

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Cholera remains a serious problem in many
countries.

• Poor access to safe water and inadequate disposal
  of sewage in resource poor countries is the main
  reason.

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• Did you come into medicine to save lives?
• If the answer is yes - perhaps you should give up
  medical school and take a course in water
  engineering.

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Find out more facts about cholera by accessing
the latest WHO fact sheet.

• WHO fact sheet on Cholera

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Find out where the latest cholera epidemic is.

• Latest Cholera Epidemics - WHO

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Find out what proportion of the world have access
to safe water and safe facilities for excreta
disposal.

• WHO figures on safe drinking water and sanitation

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Find out about deaths from diarrhoeal disease in
1998.

• WHO estimates of causes of death

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Find out how many cases of cholera were reported
to WHO last year.

• WHO figures on Cholera

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Find out how much it costs to build a safe well
or toilet in Africa.

• WATERAID

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Other routes of transmission of cholera
This is a picture of your lecturer about to eat
raw clams in Mexico (delicious!). Find out why
this was a risky idea by clicking on the picture.
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Learn more about epidemiology and control of
diarrhoeal disease.

• Supercourse Lecture