The 1850s map that changed how we fight outbreaks

see this guy he is afraid for his life this drawing is in 1832 joke it's a riff on how nobody knew how to prevent cholera you might suspend a chorus over your masked mouth or wear a copper breastplate and tie pictures of water behind your calves anything to keep the disease away [Music] starting in 1830s cholera pandemics swept the United Kingdom nobody knew how the disease was transmitted germs weren't an established idea one London doctor Jon Snow tried to find out how the disease spread and today one of his investigations is iconic in the field of Epidemiology and it all centered on a pump this is a map John snow made to prove his solution to the cholera mystery in London it also shows the confusion and the problems he was up against each of these bars represents a death from cholera the disease often killed half the people who got it it caused vomiting and diarrhea the rapid loss of fluids was fatal at the time a lot of people believed cholera was transmitted in a miasma imagine in evil cholera cloud this typical map from the 1840s shows a cholera mist that was blamed for transmission snow suspected a different source [Music] at the time people usually didn't get water directly in their homes it came from a neighborhood pump connected to one of the few water companies in the city John snow mapped different water companies service areas in London you can see how they are occasionally separate and occasionally overlap if a common pump was contaminated at any point at the source or near the pump snow believed the water could kill in 18-49 he wrote that his study of symptoms and specific cases had led him to suspect the emptying of sewers into the drinking water of the community caused outbreaks not a miasma five years later he had a chance to prove it and stop a fresh outbreak in the process in August 1854 20 people lived here at forty Broad Street including an infant who died of cholera after her death snow started to investigate the outbreak he didn't think the original water source was the problem but he thought something might be wrong down the line at the pump he took samples of the water they seemed clean but he wasn't satisfied because more people were getting sick he asked questions up and down the street where one man had noticed a bad smell from his water snow ask the Registrar for a list of people who died he started going house by house to interview the survivors and many of the dead had taken water from the pump he became convinced the Broad Street pump was the common link among the dead he wrote I had an interview with the board of guardians of st. James Parish on the evening of Thursday 7th September and represented the above circumstances to them in consequence of what I said the handle of the pump was removed on the following day people stopped using the water but snow had not won yet newspapers reported the streets were covered in line the city was using it as a powerful disinfectant on the streets that showed they weren't fully convinced the pump was the problem they suspected miasma so snow bolstered his case through investigation and recording he learned the 18 workers who died at this factory had drunk from big barrels of water drawn from the pump at the same time unlikely survivors could serve as proof of snows theory according to miasma theory this place would have been covered in cholera clouds affecting all workers but snow learned the workhouse had its own well know bad water got in the same went for this Brewer that's because snow learned the workers their drink from the breweries water supply or more likely only drank a free malt liquor they got on the job that's right drinking on the job saved their lives snow strengthened his argument and his map he adjusted the location of the pump to show how close it was to 40 Broad Street and drew a dotted line he showed a zone where it would be closest to walk to the Broad Street pump rather than another one that zone is where most people died he tabulated every death by date to do it this was paired with a local reverence similar data-driven investigations a local surveyor looked at the plumbing at 40 Broad Street where the infant had died he learned that the cesspool were sewage collected was poorly designed and lined with decaying bricks when the infants diapers had been washed the cholera carrying water had leaked into the Broad Street pump supply Jon Snow died in 1858 his obituary read dr. Jon Snow this well-known physician died at noon on the 16th instant at his house in Sackville Street from an attack of apoplexy his researches on chloroform and other anesthetics were appreciated by the profession at the time snow was more famous for stuff like a chloroform inhaler than a map it took years for the investigation of Jon Snow to become an example for subsequent outbreaks and epidemiology textbooks and it's slowly eventually helped end the miasma myth that's because snow did not just make a map of a city it's a map of his process in the field it shaped it gave direction to a world where disease didn't have to be hidden in a cloud instead it could start at a pump [Music] okay so the best book about John Snow is cholera chloroform in the science of medicine features an amazing story which is that Jon Snow gave chloroform to Queen Victoria while she was giving birth

Channel: Vox

Views: 724,960

Rating: 4.9513078 out of 5

Keywords: Vox.com, vox, explain, explainer, john snow, maps, epidemiology, cholera, broad street pump, dr. snow, cholera outbreak, dr. john snow, vox almanac, almanac, phil edwards, medicine, history of medicine, tracing, contact tracing, outbreak, pandemic, epidemic, disease history, medical history, medicines, john snow cholera, john snow epidemiology

Id: VJ86D_DtyWg

Length: 6min 57sec (417 seconds)

Published: Fri Jun 12 2020

Reddit Comments

[u/Veskerth]

Not ancient. Still cool.

[u/adx1000]

Spatial analysis! Not GIS! One of the first things we teach our first year undergrads is the difference between the two. 🙂

[u/Daebak49]

I remember learning this in Intro to GIS on how John Snow detected the source of cholera from water pumps.

[u/griffinyourface]

Not a single "you know nothing" joke yet, huh?

[u/Bottle_Kids32]

The Ghost Map by Steven Johnson is a good read on cholera and the John Snow story. Theres a pump statue and origional curb stone at the location in London. Also a nice pub, "the John Snow"

[u/ovoid709]

I spent a weekend in London a few years ago and recorded myself at the location of the well full of cholera. It's just an alley now, but that point is one of my favorite pieces of data.

[u/FeralCatColonist]

Anytime I give an intro to GIS training for our end users, the first way-back-when shout-out goes to Johann Heinrich von Thünen and the Isolated State.