ROSALIND STANWELL-SMITH: Well, my background,
I'm a medical epidemiologist.
I started off in surgery.
But I felt the call of epidemiology.
And during the '90s, I had to run a course teaching people epidemiology.
And we went down to the John Snow pub, just to give them
a kind of interesting thing.
And we found that the pub was really run-down
and no one was bothering about it.
And we knew there was this big heritage in the states
so we were really embarrassed, especially
because we had two guys from the CDC who were lecturing on our course.
As so we said, well, we must have a John Snow society.
And that's how it started.
DON GOLDMANN: The Institute for Healthcare Improvement, or IHI,
was founded by Don Berwick, who you may remember ran for governor.
He's kind of the guru of improvement.
And our mission is to improve health and healthcare around the world.
And to make care safer and better for patients and for just general people
who happen to live in a community.
And we do this with a bedrock of scientific, quality improvement.
And most people think quality improvement--
you just go out and kind of do it.
But as we've been discussing, it all involves the scientific method,
you know, prediction, testing, confirming, adjusting, constantly
running cycles, to prove or disprove that your theory of causation, how
you get from a change to a better outcome, is true.
ROSALIND: In a way, the Miasma Theory was right,
in that there are lots of factors, your general health, your wellbeing.
They even brought in your morality.
I'm afraid, you know, if you were immoral, you were going to get cholera.
But that whole idea, the holistic approach, isn't wrong as such.
But they missed out the single cause.
And people have often said, well, how was Snow absolutely strong on this?
Well even William Budd, who was a contemporary,
he came up with the Theory of Water-borne Typhoid.
He also hedged his bets.
But Snow didn't.
And I think it's very much because he was a very logical man.
But also, you look at his life.
He starts off as a young doctor in the minefields of the north of England.
And the mines, in those days, were disgusting.
You'd go down underground, there was no sanitation.
If it rained, they'd flood.
They had no way to wash their hands.
They had no toilets.
And he observed this, and commented on it.
And in 1849 he said, there must be something going on.
So he was very close to the Germ Theory.
Although he never-- he was years ahead before people like Robert Koch
came up with the Germ Theory.
But he was close.
And so he was saying, it's something, it's something
to do with them not washing the hands and ingesting it from the water.
DON: Well, first I think it's only fair to say there's no William Farr society.
And you may wonder why I would bring that up.
Well, it's because William Farr was wrong.
But he did use statistics, and one might say epidemiology,
to come to the wrong conclusion.
What he did, as you may know, is to calculate the occurrence of cholera
around London, and especially around the Thames,
by the elevation of the land above the Thames.
And he showed a really strong correlation between elevation
and lower risk of getting cholera.
Because he believed that miasmas, these noxious gases that
come from human feces and animal waste and all that kind of stuff,
all these bad gases were causing cholera.
And, unfortunately, his analysis didn't account
for all the other factors that might have been important,
income level, what kind of house you lived, what kind of water you got.
All he did was have this theory about miasmas from the Thames.
And it looks really good.
If you look at that graph, and his data, it's pretty compelling, but it's wrong.
ROSALIND: There's been a lot of criticism,
in a way, of the way John Snow and some of the others of his time
have become an icon of epidemiology.
And people have said, well, why him?
I mean he wasn't the only one doing maps,
he wasn't the only one who was beginning to look at statistics.
But what was very interesting about John Snow, I think, the deductive reasoning.
The fact that he was, yes he was a qualified doctor,
but he was very much a scientist of a doctor.
And he believed in measurement.
And he was against the flow of the times.
There were other people who thought that cholera might be waterborne.
But it was only as part of a general theory.
People sometimes want to know when did epidemiology start.
I mean, we didn't really call it epidemiology
until well later in the century.
It's really a 20th century phenomenon, as such.
They wouldn't have thought of it like that at all.
They understood epidemics because they had the word in French.
Épidémie.
But it could be just one or two cases, maybe even one case
if it was a nasty disease.
But the idea of researching those epidemics,
they would of called like a study.
Or Snow often referred to the great experiment
that needed to be done to show that water was the cause.
DON: So when this vast outbreak of hundreds of cases you said occurred,
he used basic epidemiology, and we use the term, "shoe-leather epidemiology"
to describe what he did.
He got on his feet and walked around.
And started asking, where are these illnesses occurring?
And he began to plot them out on a map, which
is sometimes called the ghost map, or John Snow's map,
so he could see patterns.
Epidemiologist essentially look for patterns of disease,
and then make a prediction, or find an association between hypothetical causes
or origins of the outbreak.
ALYSSA: When you read very short accounts of this map,
or when you see it presented in other documentaries, or whatever,
you often get the impression that John Snow is walking around Soho
with a clipboard and this map, and putting dots
and making this histogram as he walks around, which is not true.
And in fact, the more scholarly accounts that I've
read make it sound like he made the whole map after, like well after,
this was over.
ROSALIND: Yes, that's right.
ALYSSA: So, did he have a map he was making in his head?
Did he have a sketch?
Did he just use tables and have a picture in his head, or what did he do?
ROSALIND: He was very good at drawing up tables.
And there was something-- because of his work with anesthesia,
he was very good at working with compounds
and drawing out effects and things.
So he would have been making lists of the deaths.
And he would have some people like the local doctors and Henry Whitehead,
the curator, collecting the death data.
What's very interesting is his notebooks,
which he kept almost every day of his life,
for the period that he's investigating this,
is the time that he doesn't make-- he doesn't keep his notebook--
ALYSSA: He's too busy to write it down.
He's too busy.
And what I think he was doing was not using a map,
but he was collecting addresses, and so on.
And when he was presenting the information to the board of inquiry--
They set up an inquiry, immediately.
So this was a very nasty outbreak with some important people who had died,
in addition to the poor.
And so he was presenting the information,
and that's when he drew the map to convince them.
ALYSSA: The map that's on this lovely John Snow Society mug.
ROSALIND: Yes.
So he had, if you like, he'd got the data.
And this was just another way of demonstrating it.
It wasn't how he solved the outbreak.
DON: When I talk to my students about this, I always ask them,
so did John Snow perform a case control study,
which is fundamental in epidemiology.
It's the greatest tool for working up outbreaks that we have.
In a case control study, you study the exposure of the cases,
in this case, water pumps, and the exposure
of the controls, the people who were not cases, who were not sick,
and their exposure to water pumps.
And there should be a difference.
John Snow did not look at controls.
He only looked at cases.
People were sick, and arrayed them on a map,
and said these are closer to the Broad Street water pump,
and here are some exceptions to prove the rule.
So as the Father of Epidemiology, the fundamental tool
for working up outbreaks was not what he actually utilized.
ALYSSA: And the rest of London not getting sick
is not considered a control?
DON: Well, he didn't really talk about it that way.
And if you read his stuff, it wasn't-- he wasn't looking--
he had a vague idea that there were these people who weren't sick,
but it wasn't in a disciplined way.
Reverend Whitehead, who's not known as the Father of Epidemiology,
he was a local guy and he knew everybody and so
he was able to go around and ask questions.
First he found more cases.
But he also interviewed non-cases.
And that was more like a case control study.
So maybe Reverend Whitehead ought to be the Father of Epidemiology.
I mean, but John Snow, what he did was really quite remarkable.
ALYSSA: So it's at a particular moment in time
before microscopy is fully evolving as a proper science,
before the hygiene methods have really got going.
And yet Snow is 40 years ahead of his time.
In a way, it's tragic he didn't live to see that.
And what would he have contributed?
Masses, I think.
DON: Isn't it interesting that you're talking
about how theories, some based on empiric observation, some
of them remarkably astute, coexisted side-by-side with nonsense.
ALYSSA: Yes.
DON: And it's no different--
ALYSSA: It's still true
DON: --today.
ALYSSA: Yes.
DON: Right?
I mean, theories-- and I'm not going to take sides-- but creationism,
homeopathic remedies, I mean, these are wild,
to me, wild theories that exist right alongside of modern medicine
with synthetic drugs that are targeted to conformations of proteins,
and all this data we have about evolution, and climate change,
and so forth.
So I think it's a natural-- we hold on to the kind of mysterious,
the not easily explained, phenomenon and theories.
And at the same time, people will say, well, you know,
there's this thing called science, and we can actually use it to predict.