John Snow, the man with water-borne wisdom

Water pump with bucket

Water pump with bucket

It’s the anniversary of Queen Victoria’s birth on 24th May, 1819. An intriguing monarch whose influence on society is still strongly felt even now. Hers was an era of extraordinary advancement industrially and scientifically, and inquisitive pioneers whose determination to think outside norms sowed the seeds for many of the great inventions we enjoy today. One such figure that stands out in particular, bearing in mind the current health crisis, is John Snow, for he paved the way on new thinking on epidemiology as well as discovering the real cause of the cholera epidemic blighting London during his time.

Humble beginnings with a passion for learning

Snow was the son of a farmer in York. Born in 1813, the eldest of nine, his keenness to take on new information and experiences saw him focus on medical matters early; by the age of fourteen he was already an apprentice to a surgeon. Realising, though, that in order to become a properly registered physician he needed an accredited medical education, he made his way to the capital to study at the University of London, and in the process settled in Soho. Interestingly, his focus initially sighted on the field of anesthiology. And, indeed, this specialism is what brought him to the attention of Queen Victoria and saw him requested to administer relief to the queen during both the birth of Prince Leopold and Princess Beatrice. However, though he was a rising star in the field of pain management, he also began to take a very active interest in the prominent problem of the time; cholera.

A fast and furious contagion

Making its way to Britain in the early nineteenth century via sailors travelling from India, cholera brought panic and misery wherever it landed. Severe diarrhoea, nausea, and vomiting would debilitate the sufferer such that they could lose up to 20 litres of water in a day. Deathly.  Hitting hard and spreading quickly, it left death and destruction in its wake. By 1832, it had struck London.

With the havoc it wrought in the poorest districts, the favoured explanation posited that it passed via the inhalation of a poisonous miasma. But to Snow, this didn’t make sense. In his head, something that passed through inhalation would surely affect the lungs… not the digestive system; the prevailing theory didn’t add up.

Instead, he postulated a theory involving the ingestion of polluted water. This wasn’t one to get the establishment to swallow easily though, so to speak. The fact that London’s sewers openly poured their contents into the Thames, which was also the main drinking water supply for many of the poorer areas, was not an easy one to stomach. Previously, eminent ‘scientists’ had declared the water as clean as any spring found in the country and they were going to want very clear proof that Snow’s theory justifiably countered their belief.

For a while this proof proved elusive. And two things added to his woes. One, the propounders of the miasma theory were amongst the educated elite. And two, ordinary Londoners were satisfied with the concept that it was a punishment from God. A formidable opposition on the face of it, though a gentleman called the Reverend Henry Whitehead, initially another adversary, became a worthy contributor to Snow’s body of proof later.


A pale pairing

Though from a very different background, Whitehead had too been a keen pupil and devourer of knowledge as a child. However, the route he chose for a career was the cloth. And it’s just happenstance that he settled as an Anglican minister in Soho.

The severe cholera outbreak of 1854 swiftly caused him great concern. His parishioners were looking to him for answers. Why us? They were asking. And he needed a response that satisfied both them and himself.

Initially of the understanding that God was vexed, he took it upon himself to investigate cases and was keen to disprove Snow in the process. However, as he studied the circumstances of each death, he began to question his thinking.

Fortuitously, it was at this time that Snow was desperately seeking the proof he needed. He had interesting data, what he didn’t have was local knowledge. What Whitehead had was a developing fervour for an alternative explanation… and local knowledge. Despite coming to the subject from different angles, they decided to team up.

Baby Frances

Frances was the five month old baby of the local police constable, and she unfortunately succumbed very very early in the epidemic. Sad for Frances, but fortunate for Snow, for Whitehead knew the family and facilitated a useful and detailed conversation with her mother. Frances had contracted the disease on 24th August. Snow began to realise that she may well have been the initiator of the outbreak in the locale. He probed further and discovered that the baby’s nappies had been emptied into the cesspit behind their house. Nothing untoward there at all. However, the cesspit was later discovered to be leaking into the water that was drawn by the local pump for drinking; known as the Broad Street pump.

Stage one of Snow’s proof now appeared to be in place. However, he needed to counter the miasma theory properly by showing it couldn’t be linked to inhaled air. Whitehead’s local knowledge came to the fore once more. He told Snow about a lady who had died the same day as Frances, in Hampstead, and her niece who lived in Islington who’d also died the day after. Neither would have been near to Frances at any time, so neither could have breathed in the same air. Snow followed this up and discovered a clinching piece of information. The lady’s son informed him that his mother had once lived in Broad Street and liked the taste of the water there. She had therefore requested a bottle of the water from the pump be collected every day, and her niece too drank from the bottle.

Further investigation then highlighted that the local workhouse, literally just around the corner from the pump, had suffered only a small number of cases. But the building had its own well. And… the staff working in the local brewery never contracted cholera either… because they only ever drank beer. A lot was finally adding up.

Mapping out his thoughts

Snow decided to visually display the information he now had. So he mapped out the cases; a totally innovative strategy that is still used today. The Broad Street pump became a clear contender for cause of the outbreak. Together with Whitehead, he managed to persuade the local authorities that the outbreak was linked to the pump and they agreed to remove the handle. The epidemic very swiftly began to subside.

It was a small victory, though, for the powers that be in government could not readily accept that inhabitants were actually swallowing human waste, and his thoughts remained dormant. Sadly, just a short while later in June 1858, Snow then suffered a stroke and died. Perhaps a good thing for him in some respects for that summer became known as “The Great Stink”. A drought caused such foul conditions that the government was forced to take action to create a decent sewage system. This took a few years to complete, however, and during the process a new scourge of cholera hit again. This time, Whitehead was able to persuade investigators to seek out a water borne source. They discovered that the sewage laden River Lea was polluting certain reservoirs, and at long last the link between tainted water and cholera was properly forged and accepted.