He was a leading epidemiologist who would go down in history as the first person to understand how cholera was transmitted.
In this episode, we look at the amazing life of John Snow and see how he solved the mystery of cholera.
[00:00:00] Alastair Budge: Hello, hello hello, and welcome to English Learning for Curious Minds, by Leonardo English.
[00:00:11] The show where you can listen to fascinating stories, and learn weird and wonderful things about the world at the same time as improving your English.
[00:00:20] I'm Alastair Budge, and today we are going to be talking about a man called John Snow.
[00:00:27] If you are a fan of the book or TV series “Game of Thrones”, I’m sorry to disappoint you. We’re not talking about that John Snow.
[00:00:36] We are, instead, going to talk about the English doctor and leading epidemiologist, a man who would forever go down in history for being the first person to understand how cholera was transmitted, and in so doing, by some standards he would be responsible for saving millions of lives.
[00:00:56] It’s a wonderful story, so let’s get right into it.
[00:01:00] To start off our story, I must transport you to London in the year 1854.
[00:01:07] And specifically, to an area of London called Soho.
[00:01:12] You may have visited Soho, if you’ve been to London. It’s now full of bars, pubs, and shops, advertising and marketing companies, and even English language schools.
[00:01:24] But 150 years ago it was a very different place.
[00:01:29] Some streets did contain beautiful townhouses where wealthy Londoners lived and worked.
[00:01:36] Others did not.
[00:01:38] One such street is now called Broadwick Street, but back then it was called “Broad Street”. It was a slum, it was full of very poor, low quality housing.
[00:01:52] If you visited it back then you would be struck by the smell: rotting food and rubbish, human and animal waste and the refuse from butchers, slaughterhouses, and industry operating in the area.
[00:02:07] If you’ve listened to the episode on The Great Stink, episode number 233, well, you get the picture.
[00:02:14] Buildings were hugely overcrowded with large numbers of people who had relocated from the countryside, drawn to the city in the hope of finding work.
[00:02:25] Whole families might share one squalid room, living in horribly unhygienic conditions.
[00:02:32] Most buildings did not have running water or toilet facilities and the revolutionary London sewer system designed by the engineer Joseph Bazalgette had not yet been built.
[00:02:43] As a result, the streets ran with human sewage, human excrement.
[00:02:49] Cesspits - basically huge holes full of poo - lay beneath the cellars of buildings throughout the city and relied on being emptied by the so-called ‘night soil’ collectors who dumped the contents into the city’s rivers, primarily into the river Thames.
[00:03:06] Wealthy residents sent their waste via private sewers straight into the river - despite the fact the Thames served as a major source of water for drinking and washing.
[00:03:18] The result of all this was that all of the city’s water sources were full, literally, of animal and human waste.
[00:03:27] And this wasn’t just unpleasant to see or smell, or nasty to drink.
[00:03:34] People were dying of a strange illness which was given the name “cholera”.
[00:03:39] Now, this wasn’t consigned to this area of London, or even the country. There are references to cholera that date back to 1642, and doctors had observed similar illnesses all over the world, from India to China, Germany to Egypt.
[00:03:58] In 1831 two English doctors wrote about their experience of the illness in Russia, describing it in some detail in The London Gazette newspaper.
[00:04:09] Now, this is slightly graphic, but he is a passage from it. Read out by a special guest.
[00:04:16] Report from newspaper: Giddiness, sick stomach, nervous agitation, intermittent, slow, or small pulse, cramps beginning at the tops of the fingers and toes, and rapidly approaching the trunk, give the first warning.
[00:04:32] Vomiting or purging, or both these evacuations of a liquid like rice-water or whey, or barley-water, come on; the features become sharp and contracted, the eye sinks, the look is expressive of terror and wildness;
[00:04:50] The lips, face, neck, hands, and feet, and soon after the thighs, arms, and whole surface assume a leaden, blue, purple, black, or deep brown tint according to the complexion of the individual, varying in shade with the intensity of the attack.
[00:05:09] The fingers and toes are reduced in size, the skin and soft parts covering them are wrinkled, shrivelled and folded. The nails put on a bluish pearly white; the larger superficial veins are marked by flat lines of a deeper black; the pulse becomes either small as a thread, and scarcely vibrating, or else totally extinct…”
[00:05:36] Alastair Budge: Grim stuff indeed, and London too had experienced a number of cholera epidemics that killed thousands of people.
[00:05:45] And in 1854 the area around Broad Street was the centre of a particularly severe outbreak.
[00:05:54] In three days over 100 people died and in the following week most of the residents fled the area.
[00:06:01] By September, over 500 people had died.
[00:06:07] But the local authorities, the scientists and the medical practitioners could not agree on how cholera was being spread from person to person and they spent their time arguing over the relative merits of their different theories.
[00:06:24] One of the most popular was something called ‘the miasma theory’ which held that cholera was caused by particles of ‘miasma tar’ given off by decomposing rubbish and other organic matter.
[00:06:38] It was believed that miasma rose from the ground around the Thames like a mist and travelled through the air in London to be inhaled by citizens, essentially, that it was breathed in.
[00:06:53] This theory, combined with the popular belief that night air was ‘bad air’ and that ventilation after dark should be avoided, this actually contributed to the unsanitary conditions in which most Londoners lived.
[00:07:07] It might seem bizarre to us now, but back then the prevailing medical advice was to stay inside, in cramped and poorly ventilated housing so as to avoid breathing this “night air” or this cholera-contaminated air.
[00:07:25] But there was one man who did not believe this was the case, one man who had a different theory. His observation of the way cholera spread in certain areas convinced him that it was not airborne at all, but spread through water.
[00:07:43] His name was John Snow.
[00:07:47] And before we get into how he actually figured this out, I should tell you a little bit about the man himself, because his pioneering work and impact is, in many respects, unlikely.
[00:08:00] First of all, Snow was not originally a Londoner. Like so many others, he came to the city, perhaps not to seek his fortune, but certainly to find his destiny.
[00:08:11] He was born in the city of York in northern England on the 15th of March 1813.
[00:08:18] His parents, William and Frances Snow, were humble working-class people - his father, William was a manual labourer and farmer, and his mother, Frances, managed the house, looking after John and his 8 brothers and sisters.
[00:08:33] But although this might not sound like the classic breeding ground for a world-class epidemiologist, Snow’s early life was instrumental in shaping his understanding of how diseases are spread.
[00:08:48] The neighbourhood in which the Snow family lived was in one of the poorer areas of York and, significantly, it was subject to flooding from the local river.
[00:08:58] This flooding caused unsanitary, unhygienic, conditions in the houses of the local residents by contaminating water with waste from animals, sewers, industry and even from cemeteries. Nasty stuff indeed.
[00:09:14] Now, John was a very intelligent child with a great aptitude for mathematics, a skill that would play an important role in his work later on in life.
[00:09:25] He might not have been thinking about the spread of disease as a young boy in York, but his intelligence meant that he was able to get an apprenticeship with an apothecary surgeon, essentially a pharmacist that also did some basic surgical work.
[00:09:40] It was during his time working as an apprentice that the young John Snow first encountered cholera in the nearby village of Killingworth, where there was a bad outbreak.
[00:09:50] There, he helped to treat many people who were suffering from cholera, and he became familiar with its symptoms and deadly effects.
[00:09:59] Now, you probably know a bit about cholera already.
[00:10:03] Fortunately, for most of the developed world it is no longer something that concerns us, but let me quickly remind you about what exactly it is and what it does, in slightly less graphic terms than the account from the newspaper you heard earlier.
[00:10:18] Cholera is an infection of the small intestine by a bacteria called vibrio-cholera and is one of the most serious diseases that affects humans.
[00:10:28] Its symptoms are wide-ranging but one of the most significant is extreme diarrhoea that can last for days.
[00:10:36] This can be so severe as to cause dangerous levels of dehydration through the huge loss of body fluids in a very short period of time. And if not treated properly, it will kill you.
[00:10:49] Over the last 200 years there have been seven major cholera pandemics and millions of consequent deaths.
[00:10:57] The epidemic that John Snow encountered in Killingworth in the 1830s was part of the second major pandemic, one that began around 1826 in India and spread across China, Japan and Western Asia then to Europe, the Americas and Great Britain.
[00:11:14] Hundreds of thousands of people died.
[00:11:18] And this brings us back to Soho in 1854.
[00:11:23] On one side we have physicians debating exactly how this bad air is spreading cholera, but with no viable solution, no idea about how to stop transmission.
[00:11:35] On the other we have John Snow, who by this time has his own private practice in Frith Street, a few streets away from Broad Street, the centre of the cholera outbreak.
[00:11:47] As a reminder, he thought cholera was transmitted through infected water, not through bad air.
[00:11:55] So, how had he come to this hypothesis?
[00:11:59] Well, his studies showed that the transmission of the disease depended on where the water in a particular neighbourhood came from.
[00:12:08] Two of the main companies that provided water to central London drew it from polluted places, others got it from cleaner sources and filtered it to remove contaminants.
[00:12:20] The areas the latter served had measurably fewer deaths, no matter whether the inhabitants were rich or poor, male or female, young or old, or what job they did.
[00:12:32] After the Broad Street outbreak, John Snow decided to chart, to map, the incidents of cholera by interviewing local residents.
[00:12:43] He plotted the incidents of cholera on a map, and in so doing he was able to establish a pattern for the spread of the disease and he noticed something highly significant.
[00:12:55] John Snow: “Within 250 yards of the spot where Cambridge Street joins Broad Street there were upwards of 500 fatal attacks of cholera in 10 days… As soon as I became acquainted with the situation and extent of this eruption of cholera, I suspected some contamination of the water of the much-frequented street-pump in Broad Street.”
[00:13:19] Alastair Budge: Thank you John.
[00:13:21] Significantly, there were only 10 deaths in houses nearer to a different pump, and in five of those cases, the families of the deceased, the dead people, told Snow that they always used the pump in Broad Street, as they preferred its water.
[00:13:39] They preferred it despite the fact it was later discovered that the well beneath the pump had been dug near to an old cesspit that was leaking human waste! Tasty stuff indeed.
[00:13:51] In three other cases, the victims were children who went to school near the pump in Broad Street, so Snow presumed that they stopped off at that pump for a drink on their way to or from school.
[00:14:04] He went on to map the locations of cholera incidents near various other pumps and used his mathematical knowledge to illustrate the connection between the quality of the water source and the number of cases.
[00:14:17] Areas supplied with water from a sewage-polluted stretch of the Thames had a cholera rate fourteen times higher than that supplied from a cleaner area.
[00:14:27] Now, this might sound blindingly obvious to us now, “don’t drink polluted water”, but I need to stress that it wasn’t obvious at the time.
[00:14:38] After showing his calculations to the local authorities, he managed to convince them to test his theory and stop the use of the Broad Street pump by removing its handle, making it unusable.
[00:14:51] He didn’t win many friends for this, it wasn’t a popular move, as it meant that everyone around Broad Street needed to walk to the next pump to get water.
[00:15:01] But it seemed to work.
[00:15:04] Cholera deaths reduced, the outbreak ended, although Snow would himself later write that deaths had already peaked.
[00:15:12] And although today we know that cholera is indeed carried in contaminated water, and you might have thought that this was definitive proof, it would take several years for Snow’s theory to actually be definitely proved.
[00:15:28] This wouldn’t be until 1861, when the Frenchman Louis Pasteur developed his ‘germ theory’ for the transmission of diseases, and with this the miasma theory was dismissed.
[00:15:42] And indeed Snow’s theory wasn’t fully accepted until five years after this, in 1866, when one of his original opponents, who was investigating another cholera outbreak in East London, realised its truth and issued orders that all drinking water must be boiled first.
[00:16:03] Sadly by that time, Snow was dead.
[00:16:07] He suffered a stroke whilst at work on the 10th of June 1858 at the tragically young age of 45 and he never recovered.
[00:16:17] If you go to London today, you can visit all of the places I’ve mentioned: Frith Street, where he had his private practice, and Broadwick Street, where there was the cholera outbreak.
[00:16:28] And if you go to Broadwick Street you will see two signs of this great man.
[00:16:34] The first is obvious, it’s a pub called the John Snow. Although I’m not sure what John Snow would have thought about a pub being named after him as he was teetotal, he didn’t drink alcohol, and drank pure boiled water for his entire adult life.
[00:16:52] And the second is less obvious, it’s a replica pump, a pump made to look like the very pump John Snow figured was the source of the cholera outbreak.
[00:17:02] So, if you do find yourself in this area of London, go to Broadwick Street, take a look at the pump, and remember the story of this great man.
[00:17:14] You can even pop into the pub and have a pint in his memory.
[00:17:18] Or, if you want to really honour him, I’d recommend ordering his favourite drink: a glass of pure boiled water.
[00:17:28] OK then, that is it for today's episode on John Snow, the famous epidemiologist.
[00:17:35] I hope it's been an interesting one, that you've learnt something new, and that this gives you yet another place of interest to visit if you go to London.
[00:17:42] As always, I would love to know what you thought about this episode.
[00:17:46] Did you know anything about this story?
[00:17:48] Have you been to Soho, have you even stopped off for a drink in The John Snow pub?
[00:17:53] What other interesting stories are there of how diseases were discovered?
[00:17:57] I would love to know, so let’s get this discussion started.
[00:18:01] You can head right into our community forum, which is at community.leonardoenglish.com and get chatting away to other curious minds.
[00:18:09] You've been listening to English Learning for Curious Minds, by Leonardo English.
[00:18:14] I'm Alastair Budge, you stay safe, and I'll catch you in the next episode.
[END OF EPISODE]
[00:00:00] Alastair Budge: Hello, hello hello, and welcome to English Learning for Curious Minds, by Leonardo English.
[00:00:11] The show where you can listen to fascinating stories, and learn weird and wonderful things about the world at the same time as improving your English.
[00:00:20] I'm Alastair Budge, and today we are going to be talking about a man called John Snow.
[00:00:27] If you are a fan of the book or TV series “Game of Thrones”, I’m sorry to disappoint you. We’re not talking about that John Snow.
[00:00:36] We are, instead, going to talk about the English doctor and leading epidemiologist, a man who would forever go down in history for being the first person to understand how cholera was transmitted, and in so doing, by some standards he would be responsible for saving millions of lives.
[00:00:56] It’s a wonderful story, so let’s get right into it.
[00:01:00] To start off our story, I must transport you to London in the year 1854.
[00:01:07] And specifically, to an area of London called Soho.
[00:01:12] You may have visited Soho, if you’ve been to London. It’s now full of bars, pubs, and shops, advertising and marketing companies, and even English language schools.
[00:01:24] But 150 years ago it was a very different place.
[00:01:29] Some streets did contain beautiful townhouses where wealthy Londoners lived and worked.
[00:01:36] Others did not.
[00:01:38] One such street is now called Broadwick Street, but back then it was called “Broad Street”. It was a slum, it was full of very poor, low quality housing.
[00:01:52] If you visited it back then you would be struck by the smell: rotting food and rubbish, human and animal waste and the refuse from butchers, slaughterhouses, and industry operating in the area.
[00:02:07] If you’ve listened to the episode on The Great Stink, episode number 233, well, you get the picture.
[00:02:14] Buildings were hugely overcrowded with large numbers of people who had relocated from the countryside, drawn to the city in the hope of finding work.
[00:02:25] Whole families might share one squalid room, living in horribly unhygienic conditions.
[00:02:32] Most buildings did not have running water or toilet facilities and the revolutionary London sewer system designed by the engineer Joseph Bazalgette had not yet been built.
[00:02:43] As a result, the streets ran with human sewage, human excrement.
[00:02:49] Cesspits - basically huge holes full of poo - lay beneath the cellars of buildings throughout the city and relied on being emptied by the so-called ‘night soil’ collectors who dumped the contents into the city’s rivers, primarily into the river Thames.
[00:03:06] Wealthy residents sent their waste via private sewers straight into the river - despite the fact the Thames served as a major source of water for drinking and washing.
[00:03:18] The result of all this was that all of the city’s water sources were full, literally, of animal and human waste.
[00:03:27] And this wasn’t just unpleasant to see or smell, or nasty to drink.
[00:03:34] People were dying of a strange illness which was given the name “cholera”.
[00:03:39] Now, this wasn’t consigned to this area of London, or even the country. There are references to cholera that date back to 1642, and doctors had observed similar illnesses all over the world, from India to China, Germany to Egypt.
[00:03:58] In 1831 two English doctors wrote about their experience of the illness in Russia, describing it in some detail in The London Gazette newspaper.
[00:04:09] Now, this is slightly graphic, but he is a passage from it. Read out by a special guest.
[00:04:16] Report from newspaper: Giddiness, sick stomach, nervous agitation, intermittent, slow, or small pulse, cramps beginning at the tops of the fingers and toes, and rapidly approaching the trunk, give the first warning.
[00:04:32] Vomiting or purging, or both these evacuations of a liquid like rice-water or whey, or barley-water, come on; the features become sharp and contracted, the eye sinks, the look is expressive of terror and wildness;
[00:04:50] The lips, face, neck, hands, and feet, and soon after the thighs, arms, and whole surface assume a leaden, blue, purple, black, or deep brown tint according to the complexion of the individual, varying in shade with the intensity of the attack.
[00:05:09] The fingers and toes are reduced in size, the skin and soft parts covering them are wrinkled, shrivelled and folded. The nails put on a bluish pearly white; the larger superficial veins are marked by flat lines of a deeper black; the pulse becomes either small as a thread, and scarcely vibrating, or else totally extinct…”
[00:05:36] Alastair Budge: Grim stuff indeed, and London too had experienced a number of cholera epidemics that killed thousands of people.
[00:05:45] And in 1854 the area around Broad Street was the centre of a particularly severe outbreak.
[00:05:54] In three days over 100 people died and in the following week most of the residents fled the area.
[00:06:01] By September, over 500 people had died.
[00:06:07] But the local authorities, the scientists and the medical practitioners could not agree on how cholera was being spread from person to person and they spent their time arguing over the relative merits of their different theories.
[00:06:24] One of the most popular was something called ‘the miasma theory’ which held that cholera was caused by particles of ‘miasma tar’ given off by decomposing rubbish and other organic matter.
[00:06:38] It was believed that miasma rose from the ground around the Thames like a mist and travelled through the air in London to be inhaled by citizens, essentially, that it was breathed in.
[00:06:53] This theory, combined with the popular belief that night air was ‘bad air’ and that ventilation after dark should be avoided, this actually contributed to the unsanitary conditions in which most Londoners lived.
[00:07:07] It might seem bizarre to us now, but back then the prevailing medical advice was to stay inside, in cramped and poorly ventilated housing so as to avoid breathing this “night air” or this cholera-contaminated air.
[00:07:25] But there was one man who did not believe this was the case, one man who had a different theory. His observation of the way cholera spread in certain areas convinced him that it was not airborne at all, but spread through water.
[00:07:43] His name was John Snow.
[00:07:47] And before we get into how he actually figured this out, I should tell you a little bit about the man himself, because his pioneering work and impact is, in many respects, unlikely.
[00:08:00] First of all, Snow was not originally a Londoner. Like so many others, he came to the city, perhaps not to seek his fortune, but certainly to find his destiny.
[00:08:11] He was born in the city of York in northern England on the 15th of March 1813.
[00:08:18] His parents, William and Frances Snow, were humble working-class people - his father, William was a manual labourer and farmer, and his mother, Frances, managed the house, looking after John and his 8 brothers and sisters.
[00:08:33] But although this might not sound like the classic breeding ground for a world-class epidemiologist, Snow’s early life was instrumental in shaping his understanding of how diseases are spread.
[00:08:48] The neighbourhood in which the Snow family lived was in one of the poorer areas of York and, significantly, it was subject to flooding from the local river.
[00:08:58] This flooding caused unsanitary, unhygienic, conditions in the houses of the local residents by contaminating water with waste from animals, sewers, industry and even from cemeteries. Nasty stuff indeed.
[00:09:14] Now, John was a very intelligent child with a great aptitude for mathematics, a skill that would play an important role in his work later on in life.
[00:09:25] He might not have been thinking about the spread of disease as a young boy in York, but his intelligence meant that he was able to get an apprenticeship with an apothecary surgeon, essentially a pharmacist that also did some basic surgical work.
[00:09:40] It was during his time working as an apprentice that the young John Snow first encountered cholera in the nearby village of Killingworth, where there was a bad outbreak.
[00:09:50] There, he helped to treat many people who were suffering from cholera, and he became familiar with its symptoms and deadly effects.
[00:09:59] Now, you probably know a bit about cholera already.
[00:10:03] Fortunately, for most of the developed world it is no longer something that concerns us, but let me quickly remind you about what exactly it is and what it does, in slightly less graphic terms than the account from the newspaper you heard earlier.
[00:10:18] Cholera is an infection of the small intestine by a bacteria called vibrio-cholera and is one of the most serious diseases that affects humans.
[00:10:28] Its symptoms are wide-ranging but one of the most significant is extreme diarrhoea that can last for days.
[00:10:36] This can be so severe as to cause dangerous levels of dehydration through the huge loss of body fluids in a very short period of time. And if not treated properly, it will kill you.
[00:10:49] Over the last 200 years there have been seven major cholera pandemics and millions of consequent deaths.
[00:10:57] The epidemic that John Snow encountered in Killingworth in the 1830s was part of the second major pandemic, one that began around 1826 in India and spread across China, Japan and Western Asia then to Europe, the Americas and Great Britain.
[00:11:14] Hundreds of thousands of people died.
[00:11:18] And this brings us back to Soho in 1854.
[00:11:23] On one side we have physicians debating exactly how this bad air is spreading cholera, but with no viable solution, no idea about how to stop transmission.
[00:11:35] On the other we have John Snow, who by this time has his own private practice in Frith Street, a few streets away from Broad Street, the centre of the cholera outbreak.
[00:11:47] As a reminder, he thought cholera was transmitted through infected water, not through bad air.
[00:11:55] So, how had he come to this hypothesis?
[00:11:59] Well, his studies showed that the transmission of the disease depended on where the water in a particular neighbourhood came from.
[00:12:08] Two of the main companies that provided water to central London drew it from polluted places, others got it from cleaner sources and filtered it to remove contaminants.
[00:12:20] The areas the latter served had measurably fewer deaths, no matter whether the inhabitants were rich or poor, male or female, young or old, or what job they did.
[00:12:32] After the Broad Street outbreak, John Snow decided to chart, to map, the incidents of cholera by interviewing local residents.
[00:12:43] He plotted the incidents of cholera on a map, and in so doing he was able to establish a pattern for the spread of the disease and he noticed something highly significant.
[00:12:55] John Snow: “Within 250 yards of the spot where Cambridge Street joins Broad Street there were upwards of 500 fatal attacks of cholera in 10 days… As soon as I became acquainted with the situation and extent of this eruption of cholera, I suspected some contamination of the water of the much-frequented street-pump in Broad Street.”
[00:13:19] Alastair Budge: Thank you John.
[00:13:21] Significantly, there were only 10 deaths in houses nearer to a different pump, and in five of those cases, the families of the deceased, the dead people, told Snow that they always used the pump in Broad Street, as they preferred its water.
[00:13:39] They preferred it despite the fact it was later discovered that the well beneath the pump had been dug near to an old cesspit that was leaking human waste! Tasty stuff indeed.
[00:13:51] In three other cases, the victims were children who went to school near the pump in Broad Street, so Snow presumed that they stopped off at that pump for a drink on their way to or from school.
[00:14:04] He went on to map the locations of cholera incidents near various other pumps and used his mathematical knowledge to illustrate the connection between the quality of the water source and the number of cases.
[00:14:17] Areas supplied with water from a sewage-polluted stretch of the Thames had a cholera rate fourteen times higher than that supplied from a cleaner area.
[00:14:27] Now, this might sound blindingly obvious to us now, “don’t drink polluted water”, but I need to stress that it wasn’t obvious at the time.
[00:14:38] After showing his calculations to the local authorities, he managed to convince them to test his theory and stop the use of the Broad Street pump by removing its handle, making it unusable.
[00:14:51] He didn’t win many friends for this, it wasn’t a popular move, as it meant that everyone around Broad Street needed to walk to the next pump to get water.
[00:15:01] But it seemed to work.
[00:15:04] Cholera deaths reduced, the outbreak ended, although Snow would himself later write that deaths had already peaked.
[00:15:12] And although today we know that cholera is indeed carried in contaminated water, and you might have thought that this was definitive proof, it would take several years for Snow’s theory to actually be definitely proved.
[00:15:28] This wouldn’t be until 1861, when the Frenchman Louis Pasteur developed his ‘germ theory’ for the transmission of diseases, and with this the miasma theory was dismissed.
[00:15:42] And indeed Snow’s theory wasn’t fully accepted until five years after this, in 1866, when one of his original opponents, who was investigating another cholera outbreak in East London, realised its truth and issued orders that all drinking water must be boiled first.
[00:16:03] Sadly by that time, Snow was dead.
[00:16:07] He suffered a stroke whilst at work on the 10th of June 1858 at the tragically young age of 45 and he never recovered.
[00:16:17] If you go to London today, you can visit all of the places I’ve mentioned: Frith Street, where he had his private practice, and Broadwick Street, where there was the cholera outbreak.
[00:16:28] And if you go to Broadwick Street you will see two signs of this great man.
[00:16:34] The first is obvious, it’s a pub called the John Snow. Although I’m not sure what John Snow would have thought about a pub being named after him as he was teetotal, he didn’t drink alcohol, and drank pure boiled water for his entire adult life.
[00:16:52] And the second is less obvious, it’s a replica pump, a pump made to look like the very pump John Snow figured was the source of the cholera outbreak.
[00:17:02] So, if you do find yourself in this area of London, go to Broadwick Street, take a look at the pump, and remember the story of this great man.
[00:17:14] You can even pop into the pub and have a pint in his memory.
[00:17:18] Or, if you want to really honour him, I’d recommend ordering his favourite drink: a glass of pure boiled water.
[00:17:28] OK then, that is it for today's episode on John Snow, the famous epidemiologist.
[00:17:35] I hope it's been an interesting one, that you've learnt something new, and that this gives you yet another place of interest to visit if you go to London.
[00:17:42] As always, I would love to know what you thought about this episode.
[00:17:46] Did you know anything about this story?
[00:17:48] Have you been to Soho, have you even stopped off for a drink in The John Snow pub?
[00:17:53] What other interesting stories are there of how diseases were discovered?
[00:17:57] I would love to know, so let’s get this discussion started.
[00:18:01] You can head right into our community forum, which is at community.leonardoenglish.com and get chatting away to other curious minds.
[00:18:09] You've been listening to English Learning for Curious Minds, by Leonardo English.
[00:18:14] I'm Alastair Budge, you stay safe, and I'll catch you in the next episode.
[END OF EPISODE]
[00:00:00] Alastair Budge: Hello, hello hello, and welcome to English Learning for Curious Minds, by Leonardo English.
[00:00:11] The show where you can listen to fascinating stories, and learn weird and wonderful things about the world at the same time as improving your English.
[00:00:20] I'm Alastair Budge, and today we are going to be talking about a man called John Snow.
[00:00:27] If you are a fan of the book or TV series “Game of Thrones”, I’m sorry to disappoint you. We’re not talking about that John Snow.
[00:00:36] We are, instead, going to talk about the English doctor and leading epidemiologist, a man who would forever go down in history for being the first person to understand how cholera was transmitted, and in so doing, by some standards he would be responsible for saving millions of lives.
[00:00:56] It’s a wonderful story, so let’s get right into it.
[00:01:00] To start off our story, I must transport you to London in the year 1854.
[00:01:07] And specifically, to an area of London called Soho.
[00:01:12] You may have visited Soho, if you’ve been to London. It’s now full of bars, pubs, and shops, advertising and marketing companies, and even English language schools.
[00:01:24] But 150 years ago it was a very different place.
[00:01:29] Some streets did contain beautiful townhouses where wealthy Londoners lived and worked.
[00:01:36] Others did not.
[00:01:38] One such street is now called Broadwick Street, but back then it was called “Broad Street”. It was a slum, it was full of very poor, low quality housing.
[00:01:52] If you visited it back then you would be struck by the smell: rotting food and rubbish, human and animal waste and the refuse from butchers, slaughterhouses, and industry operating in the area.
[00:02:07] If you’ve listened to the episode on The Great Stink, episode number 233, well, you get the picture.
[00:02:14] Buildings were hugely overcrowded with large numbers of people who had relocated from the countryside, drawn to the city in the hope of finding work.
[00:02:25] Whole families might share one squalid room, living in horribly unhygienic conditions.
[00:02:32] Most buildings did not have running water or toilet facilities and the revolutionary London sewer system designed by the engineer Joseph Bazalgette had not yet been built.
[00:02:43] As a result, the streets ran with human sewage, human excrement.
[00:02:49] Cesspits - basically huge holes full of poo - lay beneath the cellars of buildings throughout the city and relied on being emptied by the so-called ‘night soil’ collectors who dumped the contents into the city’s rivers, primarily into the river Thames.
[00:03:06] Wealthy residents sent their waste via private sewers straight into the river - despite the fact the Thames served as a major source of water for drinking and washing.
[00:03:18] The result of all this was that all of the city’s water sources were full, literally, of animal and human waste.
[00:03:27] And this wasn’t just unpleasant to see or smell, or nasty to drink.
[00:03:34] People were dying of a strange illness which was given the name “cholera”.
[00:03:39] Now, this wasn’t consigned to this area of London, or even the country. There are references to cholera that date back to 1642, and doctors had observed similar illnesses all over the world, from India to China, Germany to Egypt.
[00:03:58] In 1831 two English doctors wrote about their experience of the illness in Russia, describing it in some detail in The London Gazette newspaper.
[00:04:09] Now, this is slightly graphic, but he is a passage from it. Read out by a special guest.
[00:04:16] Report from newspaper: Giddiness, sick stomach, nervous agitation, intermittent, slow, or small pulse, cramps beginning at the tops of the fingers and toes, and rapidly approaching the trunk, give the first warning.
[00:04:32] Vomiting or purging, or both these evacuations of a liquid like rice-water or whey, or barley-water, come on; the features become sharp and contracted, the eye sinks, the look is expressive of terror and wildness;
[00:04:50] The lips, face, neck, hands, and feet, and soon after the thighs, arms, and whole surface assume a leaden, blue, purple, black, or deep brown tint according to the complexion of the individual, varying in shade with the intensity of the attack.
[00:05:09] The fingers and toes are reduced in size, the skin and soft parts covering them are wrinkled, shrivelled and folded. The nails put on a bluish pearly white; the larger superficial veins are marked by flat lines of a deeper black; the pulse becomes either small as a thread, and scarcely vibrating, or else totally extinct…”
[00:05:36] Alastair Budge: Grim stuff indeed, and London too had experienced a number of cholera epidemics that killed thousands of people.
[00:05:45] And in 1854 the area around Broad Street was the centre of a particularly severe outbreak.
[00:05:54] In three days over 100 people died and in the following week most of the residents fled the area.
[00:06:01] By September, over 500 people had died.
[00:06:07] But the local authorities, the scientists and the medical practitioners could not agree on how cholera was being spread from person to person and they spent their time arguing over the relative merits of their different theories.
[00:06:24] One of the most popular was something called ‘the miasma theory’ which held that cholera was caused by particles of ‘miasma tar’ given off by decomposing rubbish and other organic matter.
[00:06:38] It was believed that miasma rose from the ground around the Thames like a mist and travelled through the air in London to be inhaled by citizens, essentially, that it was breathed in.
[00:06:53] This theory, combined with the popular belief that night air was ‘bad air’ and that ventilation after dark should be avoided, this actually contributed to the unsanitary conditions in which most Londoners lived.
[00:07:07] It might seem bizarre to us now, but back then the prevailing medical advice was to stay inside, in cramped and poorly ventilated housing so as to avoid breathing this “night air” or this cholera-contaminated air.
[00:07:25] But there was one man who did not believe this was the case, one man who had a different theory. His observation of the way cholera spread in certain areas convinced him that it was not airborne at all, but spread through water.
[00:07:43] His name was John Snow.
[00:07:47] And before we get into how he actually figured this out, I should tell you a little bit about the man himself, because his pioneering work and impact is, in many respects, unlikely.
[00:08:00] First of all, Snow was not originally a Londoner. Like so many others, he came to the city, perhaps not to seek his fortune, but certainly to find his destiny.
[00:08:11] He was born in the city of York in northern England on the 15th of March 1813.
[00:08:18] His parents, William and Frances Snow, were humble working-class people - his father, William was a manual labourer and farmer, and his mother, Frances, managed the house, looking after John and his 8 brothers and sisters.
[00:08:33] But although this might not sound like the classic breeding ground for a world-class epidemiologist, Snow’s early life was instrumental in shaping his understanding of how diseases are spread.
[00:08:48] The neighbourhood in which the Snow family lived was in one of the poorer areas of York and, significantly, it was subject to flooding from the local river.
[00:08:58] This flooding caused unsanitary, unhygienic, conditions in the houses of the local residents by contaminating water with waste from animals, sewers, industry and even from cemeteries. Nasty stuff indeed.
[00:09:14] Now, John was a very intelligent child with a great aptitude for mathematics, a skill that would play an important role in his work later on in life.
[00:09:25] He might not have been thinking about the spread of disease as a young boy in York, but his intelligence meant that he was able to get an apprenticeship with an apothecary surgeon, essentially a pharmacist that also did some basic surgical work.
[00:09:40] It was during his time working as an apprentice that the young John Snow first encountered cholera in the nearby village of Killingworth, where there was a bad outbreak.
[00:09:50] There, he helped to treat many people who were suffering from cholera, and he became familiar with its symptoms and deadly effects.
[00:09:59] Now, you probably know a bit about cholera already.
[00:10:03] Fortunately, for most of the developed world it is no longer something that concerns us, but let me quickly remind you about what exactly it is and what it does, in slightly less graphic terms than the account from the newspaper you heard earlier.
[00:10:18] Cholera is an infection of the small intestine by a bacteria called vibrio-cholera and is one of the most serious diseases that affects humans.
[00:10:28] Its symptoms are wide-ranging but one of the most significant is extreme diarrhoea that can last for days.
[00:10:36] This can be so severe as to cause dangerous levels of dehydration through the huge loss of body fluids in a very short period of time. And if not treated properly, it will kill you.
[00:10:49] Over the last 200 years there have been seven major cholera pandemics and millions of consequent deaths.
[00:10:57] The epidemic that John Snow encountered in Killingworth in the 1830s was part of the second major pandemic, one that began around 1826 in India and spread across China, Japan and Western Asia then to Europe, the Americas and Great Britain.
[00:11:14] Hundreds of thousands of people died.
[00:11:18] And this brings us back to Soho in 1854.
[00:11:23] On one side we have physicians debating exactly how this bad air is spreading cholera, but with no viable solution, no idea about how to stop transmission.
[00:11:35] On the other we have John Snow, who by this time has his own private practice in Frith Street, a few streets away from Broad Street, the centre of the cholera outbreak.
[00:11:47] As a reminder, he thought cholera was transmitted through infected water, not through bad air.
[00:11:55] So, how had he come to this hypothesis?
[00:11:59] Well, his studies showed that the transmission of the disease depended on where the water in a particular neighbourhood came from.
[00:12:08] Two of the main companies that provided water to central London drew it from polluted places, others got it from cleaner sources and filtered it to remove contaminants.
[00:12:20] The areas the latter served had measurably fewer deaths, no matter whether the inhabitants were rich or poor, male or female, young or old, or what job they did.
[00:12:32] After the Broad Street outbreak, John Snow decided to chart, to map, the incidents of cholera by interviewing local residents.
[00:12:43] He plotted the incidents of cholera on a map, and in so doing he was able to establish a pattern for the spread of the disease and he noticed something highly significant.
[00:12:55] John Snow: “Within 250 yards of the spot where Cambridge Street joins Broad Street there were upwards of 500 fatal attacks of cholera in 10 days… As soon as I became acquainted with the situation and extent of this eruption of cholera, I suspected some contamination of the water of the much-frequented street-pump in Broad Street.”
[00:13:19] Alastair Budge: Thank you John.
[00:13:21] Significantly, there were only 10 deaths in houses nearer to a different pump, and in five of those cases, the families of the deceased, the dead people, told Snow that they always used the pump in Broad Street, as they preferred its water.
[00:13:39] They preferred it despite the fact it was later discovered that the well beneath the pump had been dug near to an old cesspit that was leaking human waste! Tasty stuff indeed.
[00:13:51] In three other cases, the victims were children who went to school near the pump in Broad Street, so Snow presumed that they stopped off at that pump for a drink on their way to or from school.
[00:14:04] He went on to map the locations of cholera incidents near various other pumps and used his mathematical knowledge to illustrate the connection between the quality of the water source and the number of cases.
[00:14:17] Areas supplied with water from a sewage-polluted stretch of the Thames had a cholera rate fourteen times higher than that supplied from a cleaner area.
[00:14:27] Now, this might sound blindingly obvious to us now, “don’t drink polluted water”, but I need to stress that it wasn’t obvious at the time.
[00:14:38] After showing his calculations to the local authorities, he managed to convince them to test his theory and stop the use of the Broad Street pump by removing its handle, making it unusable.
[00:14:51] He didn’t win many friends for this, it wasn’t a popular move, as it meant that everyone around Broad Street needed to walk to the next pump to get water.
[00:15:01] But it seemed to work.
[00:15:04] Cholera deaths reduced, the outbreak ended, although Snow would himself later write that deaths had already peaked.
[00:15:12] And although today we know that cholera is indeed carried in contaminated water, and you might have thought that this was definitive proof, it would take several years for Snow’s theory to actually be definitely proved.
[00:15:28] This wouldn’t be until 1861, when the Frenchman Louis Pasteur developed his ‘germ theory’ for the transmission of diseases, and with this the miasma theory was dismissed.
[00:15:42] And indeed Snow’s theory wasn’t fully accepted until five years after this, in 1866, when one of his original opponents, who was investigating another cholera outbreak in East London, realised its truth and issued orders that all drinking water must be boiled first.
[00:16:03] Sadly by that time, Snow was dead.
[00:16:07] He suffered a stroke whilst at work on the 10th of June 1858 at the tragically young age of 45 and he never recovered.
[00:16:17] If you go to London today, you can visit all of the places I’ve mentioned: Frith Street, where he had his private practice, and Broadwick Street, where there was the cholera outbreak.
[00:16:28] And if you go to Broadwick Street you will see two signs of this great man.
[00:16:34] The first is obvious, it’s a pub called the John Snow. Although I’m not sure what John Snow would have thought about a pub being named after him as he was teetotal, he didn’t drink alcohol, and drank pure boiled water for his entire adult life.
[00:16:52] And the second is less obvious, it’s a replica pump, a pump made to look like the very pump John Snow figured was the source of the cholera outbreak.
[00:17:02] So, if you do find yourself in this area of London, go to Broadwick Street, take a look at the pump, and remember the story of this great man.
[00:17:14] You can even pop into the pub and have a pint in his memory.
[00:17:18] Or, if you want to really honour him, I’d recommend ordering his favourite drink: a glass of pure boiled water.
[00:17:28] OK then, that is it for today's episode on John Snow, the famous epidemiologist.
[00:17:35] I hope it's been an interesting one, that you've learnt something new, and that this gives you yet another place of interest to visit if you go to London.
[00:17:42] As always, I would love to know what you thought about this episode.
[00:17:46] Did you know anything about this story?
[00:17:48] Have you been to Soho, have you even stopped off for a drink in The John Snow pub?
[00:17:53] What other interesting stories are there of how diseases were discovered?
[00:17:57] I would love to know, so let’s get this discussion started.
[00:18:01] You can head right into our community forum, which is at community.leonardoenglish.com and get chatting away to other curious minds.
[00:18:09] You've been listening to English Learning for Curious Minds, by Leonardo English.
[00:18:14] I'm Alastair Budge, you stay safe, and I'll catch you in the next episode.
[END OF EPISODE]
