John Snow (the other one)

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No, not that one


That one

I’m in lockdown. My Twitter feed has words filtered from it, my ears are tuned to the merest mention on the TV, and my eyes watch for posts to Facebook. You see, I am going off to Sierra Leone at a crucial time.

We are 3 weeks into a new season of Game of Thrones and I won’t get to see any of it til the end of July. I am acutely aware of the possibility of spoilers.

So in this post I’m going to recount the tale, told in epidemiology story-times across the world, of the other John Snow. I was in London last week and took the opportunity to make a pilgrimage to the place where it all began (said place is now, conveniently, a pub, and next door there is an equally convenient lovely coffee and chocolate cafe, but I can assure all my readers I went there purely for the epidemiological culture). Incredibly, it all began only 160 years ago when London still had the occasional outbreak of everybody’s favourite old-skool diarrhoeal illness, cholera.

160 years ago, the most popular theory for the spread of disease was that it was spread through ‘bad air’ or miasma. Essentially, it was thought that pollution and bad smells were the means by which disease was caught – germ theory was yet to be proposed. John Snow, a London physician (who, not content with fathering one branch of medicine – epidemiology – also made significant contributions to anaesthesia) was sceptical of the miasma theory and thought cholera might be transmitted through water. After publishing his theory to limited acceptance in 1849 (“You know nothing, John Snow,” the medical establishment said)….


….he investigated further when an outbreak of cholera hit Soho, London in 1854.

IMG_3269Snow, together with a local clergyman, did the first spatial mapping of disease. He found that people affected by cholera were far more likely to have collected their water from the pump on Broad Street than the other nearby pumps. Legend has it that he removed the handle from the pump and the cholera stopped, but as is so often the case the reality is more mundane. He convinced the council of his findings and they removed the pump handle. (And in fact the case numbers had started to drop quite substantially before the handle was removed anyway, but I think we should give him credit for convincing a council of something if nothing else.)

And so epidemiology was born. And then they put a pub where where there had previously been a cholera-dispensing water pump. It has a blue plaque and a picture of the man himself on the sign.

He might not be the most famous John Snow on the Internet (and from his pictures he looks like he might have actually been having less fun than the other one too), but he did something pretty cool nevertheless.

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