An 1856 autotype portrait of Dr. John Snow, the Father of Epidemiology, and his impressive sideburns.
Image: Wikimedia Commons
Even the most casual Game of Thrones fan knows Jon Snow, the illegitimate son of the late fan favorite, Ned Stark. As a man of the Night’s Watch, Jon Snow is charged with defending Westeros from the terrors beyond the Wall, including keeping Wildling invasions and the terrifying Others (White Walkers) at bay.
However, many of you have probably not heard of another John Snow who went down in history as a great defender of men. Now known as the Father of Epidemiology, this John Snow was a 19th century doctor and revolutionary thinker who bucked the established paradigm of then-modern thought.
A MAN OF THE NIGHT SOIL
In the mid-1800’s, Soho in London’s West End was not exactly the height of fashion. It was a squalid, densely populated working-class neighborhood that was largely neglected by the well-to-do of London. At this time, Soho’s residents depended on poorly maintained cesspits or the River Thames for waste disposal, rather than a well-planned sewage system.
The poor quality of Thames drinking water depicted in William Heath’s 1828 cartoon, A monster soup, commonly called Thames Water.
Image: Wellcome Images
This lack of basic water and sanitation infrastructure meant that the many residents of Soho were swimming in their own filth. Accounts from this time describing cellars three feet deep in human excrement and nearly opaque drinking water the color of green tea feel ripped from Martin’s pages on Flea Bottom, with the glaring difference that these accounts are not works of fiction.
A member of both the Royal College of Surgeons of England and the Royal College of Physicians, John Snow not-of-Winterfell fought to combat poor hygiene and disease. Though he was by training an anesthesiologist (he personally administered chloroform to Queen Victoria during the birth of her two youngest children), recent cholera outbreaks in Soho attracted his attention. The end of August 1854 had brought with it a particularly bad bout of this disease, killing 127 people within the first three days of the outbreak.
A transmission electron microscope image of the bacterium that causes cholera, Vibrio cholerae.
Image: Tom Kirn, Ron Taylor, Louisa Howard – Dartmouth Electron Microscope Facility
FORGING A SILVER CHAIN
Today, we know that cholera is spread through food and water contaminated with feces containing the bacterium Vibrio cholerae. In 1854, however, the idea that living, microscopic organisms cause infectious diseases, called the “Germ Theory of Disease,” would not have been accepted by the medical profession, as Louis Pasteur did not come up with it until 1861.
The “Miasma Theory of Disease” that pervaded at that time had existed since medieval times. It stated that foul, poisonous air made people sick; in fact, this idea was how the disease malaria got its name, being medieval Italian for “bad air.”
Though John Snow knew as little about infectious microbes as anyone else at the time, his observations about the patterns of the spread of disease led him to believe that bad air had nothing to do with it. He traveled from house to house, collecting data on the sick and the deceased in order to map out the source of the outbreak.
By asking questions about people’s habits and behavior, he found that the common connection between many of the sick was that their main source of drinking water was a water pump that sat on the corner of Broad Street and Cambridge Street.
John Snow’s map of cholera cases in Soho. Each black bar represents one case of cholera. The Broad Street pump is marked in the center of the map.
Image: John Snow, M.D., On the Mode of Communication of Cholera
By the time the Board of Guardians of St. James’s Parish met on September 7th, 1854, nearly 500 people had died from the cholera outbreak that was sweeping through Soho. Firmly believing the Broad Street pump to be the center of the outbreak, John Snow testified in front of the Board, urging them to remove the pump’s handle in order to stop further spread of the disease.
“YOU KNOW NOTHING, JOHN SNOW”
Though the Board was skeptical of his claims, they took his advice and mandated that the handle be removed from the Broad Street pump to block the source of the disease. The outbreak waned shortly after the handle was removed, but few really believed Snow’s theory.
The fact was that nobody wanted to believe that the disease was being spread through drinking water contaminated with human feces; despite the obvious evidence that the water was filthy, this thought was too vile to be readily accepted. The end of the outbreak did not help his case, either – Snow was the first to admit that the outbreak had already been on the decline before they took action.
Despite this reluctance to believe Snow’s theory that disease is contagious, evidence kept piling up in his favor against the claims of those who believed in the Miasma Theory of Disease.
George Pinwell’s 1866 cartoon, Death’s Dispensary, depicting the Broad Street Pump as the source of the 1854 Soho Cholera outbreak.
Snow set out to find more convincing evidence for the connection between contaminated water and cholera infection, and discovered that those who avoided drinking from the Broad Street Pump did not become infected.
Just one block away from the Broad Street pump, workers in a local brewery and monks from a nearby monastery did not become ill, despite being surrounded by the sick. It turned out these men took a page out of the Lannister playbook; rather than drinking water, they exclusively drank alcohol, specifically the beer they brewed within their own walls.
Further investigation found that of the 535 malnourished inmates living in the terrible living conditions of a Soho workhouse, only 5 became ill. This workhouse had its own, independent source of water.
With the help of fellow contagionist Dr. Joseph J. Whiting, Snow extended his inquiries by asking residents around South London which company supplied their drinking water. They were particularly suspicious of the Southwark and Vauxhall Water Company, which could have caused cases later in the outbreak by pulling water from the Thames downstream of where cholera-contaminated sewage was dumped into the river.
A table from John Snow’s 1856 paper, Cholera and the water supply in the south districts of London, 1854, showing the connection between the Southwark and Vauxhall company’s water and deaths due to cholera.
When they compared these findings to the incidence of cholera in Soho, Snow found that 286 of the victims of the most recent outbreak drank Southwark and Vauxhall water, whereas only 14 drank water from another company that pulled water upstream of the sewage inputs (it was unknown which company provided water to the remaining 34.)
Despite the evidence in favor of John Snow’s theory, the Miasma Theory prevailed until Louis Pasteur’s development of the Germ Theory a decade later.
He may not have killed a White Walker, fought off a Wildling invasion, or even managed to convince people that disease is contagious. Still, John Snow’s impact was profound. Snow’s investigations established a new way of thinking about disease; by trying to understand human behavior and find patterns surrounding the outbreak, he laid the foundation for the field of epidemiology as we know it today.
And so – it seems it’s safe to say that in spite of the staunch opposition of the Miasmatists, you know plenty, John Snow.