Early experiences in fighting a pandemic.  

The lessons of John Snow, the founding father of epidemiology, are still relevant during the coronavirus pandemic

When a geographer, who writes a newsletter, gets vaccinated against a contagious disease, you may expect a few words about John Snow, the first man to find the source of an epidemic by plotting all patients on a map. 

I guess most of you will have heard at least part of this story before, but you may not have recognized John Snow's name. Even fewer people knew who he was when he died at 45 in London in 1858. We now recognize him as the founding father of epidemiology, but The Lancet wrote only a brief obituary, and that was about it. However, the fame of the famous is never constant in history, and John Snow's star has been rising over the years. For instance, Snow is the only teetotaller and vegan I ever heard of who has a pub named after him. And not far from this pub in Soho, London, is the John Snow water pump. 

Let's start this story in York in 1813, where John was born as the son of a laborer in the local coal yard. I couldn't find his mother's job, but with nine children living on a small laborer's income in one of the most impoverished areas of York, I can only guess at how busy she must have been. From anything I have read over the years about the sanitary conditions in England in the 18th and 19th centuries, I understand that it must have been an enormous challenge to raise kids. To formulate this more clearly: it was a challenge to keep all of them alive. I don't have the numbers for Snow's family nor York in the early 19th century; a very rough guess is that around 15 percent of children didn't live to see their fifth birthday. I won't exclude a significantly higher percentage; London and the textile and mining areas had a worse reputation for child mortality. 

Little John Snow grew up in unsanitary conditions; the runoff from cemeteries and sewage polluted the waters. At the age of 19, he encountered his first cholera epidemic in Killingworth, a coal-mining village. That experience may explain why he became a vegetarian and later a vegan, who also drank only tea or distilled water. I am a vegetarian in the 21st century, and from anything I have read about the conditions in the 19th century, I am pretty confident I would have joined him. 

Snow made an impressive career, especially considering his humble beginnings in a time and country with considerable class barriers. At the age of 23, he started at medical school in London, and he earned his MD at the University of London eight years later. 

Snow focussed most of his career on anesthesia, especially on the use of chloroform during childbirth. I often wonder how different the world would be if nature had decided that men would be the ones to give birth. I note that thought here because many of his male colleagues and the Church of England opposed using chloroform as an anesthetic during childbirth. These influential men called it 'unethical,' and I guess they would have altered their opinion if nature had decided to give men the task for childbirth. That all changed when Queen Victoria, usually not on the barricades for progressive innovations, asked John Snow to administer chloroform while delivering the last two of her nine children.

It is hard to imagine how filthy London was in the mid-19th century. It was overcrowded, there was a lack of anything that we now follow as personal hygiene, and instead of the famous black cabs, there were thousands of horse-drawn vehicles that left piles of manure in the streets. It was the London of Dickens, a man who promoted soap and raised awareness about the impact of live cattle markets in the city. This early environmental activist wrote in 1851:

"In half a quarter of a mile's length of Whitechapel, at one time, there shall be six hundred newly slaughtered oxen hanging up, and seven hundred sheep but, the more the merrier proof of prosperity. Hard by Snow Hill and Warwick Lane, you shall see the little children, inured to sights of brutality from their birth, trotting along the alleys, mingled with troops of horribly busy pigs, up to their ankles in blood but it makes the young rascals hardy. Into the imperfect sewers of this overgrown city, you shall have the immense mass of corruption, engendered by these practices, lazily thrown out of sight, to rise, in poisonous gases, into your house at night, when your sleeping children will most readily absorb them, and to find its languid way, at last, into the river that you drink."

Cholera is a deadly disease that was not known in London until it arrived in the UK from India in 1831. The city had multiplied in population, but the infrastructure to deal with human and other waste was underdeveloped. Sewage was coming into contact with drinking water, and the river Thames was both a colossal sewage canal and a source for drinking water. It was the ideal setting for several devastating cholera epidemics. 


Experts believed that this disease was air-borne and spoke about 'miasma,' the poisonous vapors of rotting organic matter. And indeed, where the air was most filthy, in the overcrowded slums, most people died. But cholera is water-borne, and the sewage situation was even more worrying than the foul air. I will spare you the descriptions of overflowed basement cesspits; I know some of you read my newsletters during breakfast. It suffices to say that while reading into this subject, I realized how happy I am to have lived in London of the late 20th century and not 150 years earlier.

This city was the London of John Snow, who was the right man at the right time to make history. The man who had grown up in unsanitary conditions, who had seen his first cholera outbreak at the age of 19, and who had decided to drink only tea or distilled water. As a doctor with a good reputation, he was the ideal man to study the spreading of this disease. He did not understand what transmitted the illness, but he couldn't find evidence for bad air causing it. He also remembered the first cholera epidemic he had witnessed in that mining village. The miners worked deep underground, were not breathing the air of the sewers, and still died of cholera. He believed something else than air transmitted the disease.


If you have visited London, you may have been in Soho, the district with many pubs and restaurants. It is hard to imagine a terrible outbreak of cholera in the heart of Soho in 1854. It was here that John Snow interviewed residents and plotted all cholera cases on a map of the district. He thus concluded that the source of the outbreak was the public water pump on Broad Street. He showed the pattern of the disease to the local council and managed to persuade them to remove the handle from the public pump to stop the spread of the disease. 

It took years before Snow's theory was entirely accepted; there have always been, and there always will be forces against science. Victorian England saw the message that a disease might spread through the water as too unpleasant. You could say it was the climate change of its day since the message that we should stop burning fossil fuels is also too unpleasant for some. The handle was put back up when the outbreak was over, and nobody paid attention to its water quality. But in the decades to follow, London did start to improve the city's infrastructure. Driving on Embankment, you are going on top of the sewers constructed parallel to the Thames to transport the sewage out of London without letting it pollute the river. 

Our knowledge of epidemics is now so much better than in the time of John Snow. But the skeptics of science are still around, ignoring science-based precautions, and opposing vaccinations, until they get infected and demand the best science-based treatments to keep them alive. It even happens at the highest levels. We also saw during this pandemic that scientists can achieve tremendous progress in a relatively short time if politicians give a crisis the priority it needs, listen to scientists, and fund their research. We owe a lot to the double-blind scientific methodology of John Snow and all who have followed in his footsteps. Next time in London, I plan to drink a beer, or a cup of tea, in The John Snow pub to honor him. 

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John Snow: See page for author, Public domain, via Wikimedia Commons

Photo pub: Jamzze, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

Map of Soho: See page for author, CC BY 4.0 <https://creativecommons.org/licenses/by/4.0>, via Wikimedia Commons

Cartoon: See page for author, CC BY 2.0 <https://creativecommons.org/licenses/by/2.0>, via Wikimedia Commons