““Everything you wanted Everything you wanted to know but never knew to know but never knew

about until now”about until now”presentspresents

…………………………. ………………………….John SnowJohn Snow

The BasicsThe Basics

►Often called the Father of Modern Often called the Father of Modern EpidemiologyEpidemiology

►Way ahead of his time in theories and Way ahead of his time in theories and practicepractice

►Specialized in cholera casesSpecialized in cholera cases

What the heck is What the heck is epidemiology?epidemiology?

► Comes from the Comes from the word “epidemic” word “epidemic”

►The branch of study The branch of study that relates to the that relates to the causes, causes, distribution , and distribution , and control of diseases control of diseases in populations. in populations.

Back to Snow…Back to Snow…

►His uneventful birth was on March 15, His uneventful birth was on March 15, 18131813

►Went to a private school until he was 14 Went to a private school until he was 14 and become a surgical apprenticeand become a surgical apprentice

►His parents were determined to give all His parents were determined to give all of their children whatever education of their children whatever education they could affordthey could afford

► Interested in math, which might have Interested in math, which might have helped his study on cholera. helped his study on cholera.

What the heck is cholera?What the heck is cholera?

►Caused by Caused by vibrio vibrio choleraecholerae bacteria in bacteria in intestineintestine

►Severe diarrhea and Severe diarrhea and dehydrationdehydration

►Can kill within a dayCan kill within a day

Back to Snow…Back to Snow…

►Served as a coal mine surgeon and Served as a coal mine surgeon and assistant during the first London assistant during the first London Cholera Epidemic of 1831-2Cholera Epidemic of 1831-2

►Went to Huntierian Medical schoolWent to Huntierian Medical school►Received the unexpected honor of Received the unexpected honor of

being accepted into the Royal College being accepted into the Royal College of Surgeons of Englandof Surgeons of England

And finally…And finally…

► John snow John snow graduates M.D graduates M.D from the from the University of University of London in 1844London in 1844

But wait!But wait!

► Snow was a rebel when it Snow was a rebel when it came to how he believed came to how he believed cholera was transmittedcholera was transmitted

► Opposed the commonly Opposed the commonly held idea that cholera held idea that cholera was transmitted through was transmitted through breathing contaminated breathing contaminated air, also called the air, also called the miasma theory.miasma theory.

The Snow TheoryThe Snow Theory

►Published his first work “On the Model Published his first work “On the Model of Communication of Cholera” in 1849of Communication of Cholera” in 1849

►Earth-shattering proposal: Cholera Earth-shattering proposal: Cholera reproduced in the human body and reproduced in the human body and spread through food or waterspread through food or water

►But he couldn’t prove it!! Yet!But he couldn’t prove it!! Yet!

Until….Until….

►1854, when another cholera outbreak 1854, when another cholera outbreak struck London, struck London,

►Snow rubbed his hands together and Snow rubbed his hands together and got to work, investigating two water got to work, investigating two water companies. companies.

HeHeHe!!!HeHeHe!!!

►Snow found that London was supplied Snow found that London was supplied water by two companies, one of which water by two companies, one of which pulled out water from the Thames pulled out water from the Thames river, famous for its filth, and the other river, famous for its filth, and the other from an downstream river. from an downstream river.

                                                                    

                                             

So the Wily Snow…So the Wily Snow…

►Plotted the location of deaths related Plotted the location of deaths related to cholera around the London areato cholera around the London area

►Found a pattern and a big Found a pattern and a big concentration of deathsconcentration of deaths

►Traced the source to the Broad Street Traced the source to the Broad Street pumps where 500 people had died in pumps where 500 people had died in 10 days!10 days!

Ha Ha Hypocrite!Ha Ha Hypocrite!

►City officials removed the Broad Street City officials removed the Broad Street pump and the epidemic died off.pump and the epidemic died off.

►Snow finally proved himself!Snow finally proved himself!

Snow’s EndSnow’s End

►Died four years after his triumphant Died four years after his triumphant discovery, 1858, at the age of 45. discovery, 1858, at the age of 45.

►Snow’s work remains a classic study of Snow’s work remains a classic study of epidemiology and set the precedence epidemiology and set the precedence for years to come. for years to come.