Monday, July 28, 2008

one of these days I'll give in and get that degree in medical anthropolgy...

The Ghost Map: The Story of London's Most Terrifying Epidemic - and How It Changed Science, Cities, and the Modern World
by Steven Johnson

I'm always amazed by how much science has changed in the past 200 years. At the time of London's worst and last cholera epidemics, almost the entire scientific community was convinced the disease was carried via "miasma", or noxious odors. The fact that there was raw sewage being pumped into the Thames or sitting, festering, in peoples' basements because they couldn't or wouldn't pay for it to be taken to the countryside for disposal, had nothing to do with the spread of disease. Riiiiight.

There was an outbreak of cholera in Soho in 1854; John Snow, an epidemiologist, and Henry Whitehead, the local preacher, worked against each other and then together, as they learned more, to backtrack the spread of the disease. Snow was looking to disprove the misasma theory and Whitehead had intimate knowledge of the community, and together they determined that, after victim zero, the disease had spread to hundreds of nearby people via one particular pump. This involved tracing where people got their water, and when, and learning how the pump became infected (remember those nasty basements I mentioned above? a diaper from a cholera-infected baby infected the ground water in her basement, which passed into the well below the pump, which in turn killed hundreds of people). This was not an easy task, but there were helpful indicators. For example, a local brewery employed many men, and supplied them with all the beer they wanted while they worked, and didn't draw its water from the infected well. Those men drank enough beer while at work that they weren't thirsty at other times, and, despite being very close to ground zero, weren't affected. A former resident of the area thought the water from that particular well tasted better than other water, so her sons would regularly bring her a jug of the water. She died of cholera in the countryside.

Snow's research methods were unprecedented - though it seems obvious now, he was the first to plot the deaths on a map, and then determine which households were closer to the Broad street pump than any other, tracing that radius on the same map. The enclosed area was not a well-defined circle, but a jagged shape due to the intricacies of the streets, and pretty much enclosed the entire area suffering the cholera deaths, and only that area. Freaking brilliant.

Of course, the powers-that-be were still fixed on the miasma theory, and, despite Snow and Whitehead's work, it took another ten years or so for it to be accepted as crap. Snow died before receiving true recognition.

But once accepted, the issue of disease transmission via water was responsible for the construction of London's sewer system in the 1860's or so, much of which is still in use and now handles the waste of millions and millions of people. It led to the general clean-up of cities around the world, and enabled them to grow to the immense sizes they are today.

There's an epilogue where Johnson goes on for a while relating cholera to terrorism and other stuff. Wasn't entirely sure where that came from, but the majority of the book (pretty much all the historical portions) was fascinating.

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posted by ket at 10:52 PM


Blogger ~e said...

i agree, this was a good one!

8/22/2008 9:19 PM  

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