John Snow and cholera

• Medicine in 18th- and 19th-century Britain saw great change, especially following the publication of Louis Pasteur's germ theory
• This led to significant changes in surgery and better prevention of disease in the late 19th century
• Cholera


  A bacterial infection caused by contaminated drinking water
• Miasma


  Smells from decomposing material, such as animal and human waste, that were thought to cause disease
• The Industrial Revolution saw a growth in the population of cities, such as London
• The increased population led to overcrowding and more waste on the streets, coupled with a lack of proper sanitation or sewerage for the growing populations
• The first time that the disease cholera came to Britain was in 1831
• Beliefs about preventing cholera

  • Burning barrels of tar to remove the bad air
  • Praying
  • Taking medicines that promised protection
  • Burning the clothes and bedding of victims
• John Snow


  A doctor who believed cholera was spread in water and not by miasma
• John Snow's investigation of the 1854 cholera outbreak


  1. Plotted each death on a map

  2. Proved the people who had died all lived close to a specific water pump

  3. Removed the handle from the water pump so it could not be used

  4. Discovered a cesspit close to the pump had been leaking waste into the water supply
• John Snow was able to prove that dirty water was causing the spread of cholera
• Many people continued to believe that disease was spread by bad air, which did not change until Louis Pasteur discovered bacteria
• John Snow did not know it was bacteria in the water that was spreading cholera
• Bacteria


  Single-celled microorganisms, some of which are pathogenic in humans, animals and plants
• John Snow discovered that cholera was spread by dirty water and not bad air