What did John Snow know?

So there are two things I'd like to pick up on there.

The first is this thing that he constructed.

You can still see them today, these very evocatively called ghost maps, if you could tell us about those.

And then maybe a bit about why we're reluctant now to refer to him as the father of epidemiology, while that isn't a term we'd use so much these days.

So maybe to take the second one first, I mean, that's something actually we've been talking about in the John Snow Society, which perhaps we'll talk about later.

It's a term that has had great use over the years.

But, you know, epidemiology has many roots.

And Snow was not the founder of the discipline of epidemiology alone.

He didn't discover the transmission of cholera alone.

There are many, many people involved in the story in Broad Street, in the wider explication of cholera as a waterborne disease.

And of course, that terminology, the father epidemiology, is somewhat gendered.

So we think of him in the John Snow Society, which is a lighthearted but serious society that celebrates his contribution to epidemiology.

as somebody with a really important role in a really interesting, you know, it's a nice story for teaching about epidemiology and cholera, but sort of shy away from the idea of a father of epidemiology.

The ghost map question, I'm not sure if I'm the best place to answer that, Niall, to be honest.

I think the one thing I would say about the famous ghost map is it's, again, another fabulous example of sort of intuitive sort of public health investigation and research.

So moving from the pump to identifying the households which used it.

that pump, and then a sort of simple visual representation of the deaths which were occurring within each household.

And then, of course, following that spatial description with further interviews with, for example, workers in the brewery that were not falling sick because they They were drinking beer instead of water from the pump.

And the famous story of a woman that had moved from that area to Hampstead but sent her servant down to collect water from the pump.

And sadly, both the servants and the woman sort of died that then provide further confirmatory evidence on the sort of spatial distribution of these cases linked to use of the pump.

And the reason I think it's so exciting is that, you know, zipping forward a century, century and a half, spatial epidemiology is becoming more and more important as we begin to understand that how people and pathogens and risk factors are distributed within populations and how they coexist.

Today, you can root a lot of that very interesting work, which helps us sort of understand in my world of environmental health, how the environment influences people's health, right the way back to that simple map.

So, yeah, for me, at least, as James said, you know, the value of the story of Jon Snow is often as an example to teach epidemiology and teach these basic methods and how they can be applied in public health.

And it's also where, at least back in my day, the definition of epidemiology came from.

We were taught that Jon Snow was one of the first people to identify the importance of looking at person, place, and time.