John Snow

Cholera Outbreak in London1854

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conditions in Europe. Gives you an idea of the streets of London in the 19th century.

Who is John Snow?

• John Snow is a British doctor who lived from 1813 to 1858.

• He is considered by many to be the father of epidemiology.

• Epidemiology is a branch of science that studies the cause, distribution and control of a disease in populations.

• John was such a good doctor that he even used anesthesia on Queen Victoria when she was giving birth to her eighth and ninth children!

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Queen Victoria

Open drop method, administration of chloroform used by John Snow on Queen Victoria

Prince Leopold

Princess Beatrice

What is John Snow best known for?• John Snow is best known for figuring out that cholera is

spread through contaminated water.• During the first half of the 19th century most people

believed cholera was spread through miasma also known as bad air. They thought Dr. Snow’s theory was ridiculous.

• He was extremely influential in curbing the cholera outbreak in Soho, London during September 1854.

• Let’s look at how he helped Londoners in the early fall of 1854.

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What happened in Soho in September 1854?

• On the night of August 31st, 1854 a terrible outbreak of cholera started.

• Three days later 127 people were dead.• All of these deaths were of people living in and around

Broad Street.• While a majority of the residents of Soho were

evacuating the area, John Snow saw his chance to prove his theory and started interviewing the families of the victims.

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What did John Snow discover?

• He found "that nearly all the deaths had taken place within a short distance of the pump."

• The pump he was referring to was on the corner of Broad Street and Cambridge Street.

• Next Dr. Snow took a sample of water from the pump on Broad Street. When he put the water under a microscope he observed "white, flocculent particles." This was not normal water!

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John Snow’s map documenting the cholera deaths in Soho

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Each line represents one death

How did John Snow stop the spread of cholera?• John Snow had all the information he needed and on

September 7th he took his findings to the local council.

• The local council did not believe him, but removed the handle to the Broad Street pump anyways.

• Once the pump handle was removed the incidences of cholera were drastically reduced.

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How many people died during the outbreak?

• By the end of September the cholera outbreak was over and 616 people were dead.

• John Snow was still upset because people did not believe his theory that cholera was spread by contaminated water. The public cited examples such as cases of cholera located outside of Soho. Dr. Snow had a lot of work to do to convince the public.

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How was John Snow able to prove his theory?• In groups of two read the article titled, ‘John

Snow and the Broad Street Pump: On the Trail of an Epidemic’ or ‘Broad Street Pump Outbreak’ and answer the questions on the corresponding handout.

• After reading the article you should be able to explain to the class how John Snow proved his theory.

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