I have belatedly discovered the 2007 Steven Johnson book The Ghost Map: The Story of London's Most Terrifying Epidemic--and How It Changed Science, Cities, and the Modern World. My wife gave it to me for Christmas, and it promptly shut me up—as we say chez Kilian about a really good book.
The Ghost Map is the story of Dr. John Snow and the famous Broad Street pump, but it's much more than that; it's also a social history of Dickensian London, when almost half the population made a living cleaning up and recycling the other half's waste. Even dog shit had a market—the tanners who called it "pure" and used it to clean the lime out of animal hides, once the lime had removed the fur—and therefore it supported a corps of "pure finders."
This is also the story of a paradigm shift in science, from the miasma theory of disease transmission (it's all in the air) to the concept of waterborne agents of illness. Beyond that, it's the story of the founding of modern epidemiology. And it is a brilliant study of how only in cities could cholera become a problem, and only in cities could its solution be found.
I'd had only a fuzzy concept of Dr. Snow's achievement, mostly based around his checking the addresses of people who caught cholera in his neighbourhood in a few brutal days in August and September 1854. Marking those cases on a street map, he found them all users of water from the Broad Street pump. Somehow I thought Snow personally had removed the pump handle; he did no such thing.
Snow was already a success story, a young doctor from humble origins who began studying anesthesia within a few weeks of the first operation using ether. He was soon Britain's leading anesthesiologist, first with ether and then with chloroform, and even attended the birth of Queen Victoria's eighth child (Her Majesty was very pleased to have been knocked out).
Much of Snow's practice was devoted to a much poorer clientele in his own neighbourhood. When people began to fall ill with cholera, he was professionally concerned. But he was also professionally concerned with the disease's failure to behave as current medical theory said it should.
For a long time, the "miasmatics" had dominated medical thought, believing that disease was caused by some agent in foul air. God knows Victorian Britain had plenty of it. The stench of human and animal excrement was everywhere, but especially in the housing of the poor.
In many tenements, the basements were simply where shit was dumped, to be dug out by the night-soil men. (I saw their modern equivalents in 1983 China, the honey-wagon men scooping out the poop from under our apartment building in Guangzhou.) But if the landlord couldn't afford their fees, the poop just stayed in the basement.
Received medical theory also argued that the unsanitary habits of the poor resulted in their being more susceptible to disease, simply because the slums stank worse than the upper-class neighbourhoods. London's first sewers only made matters worse: Designed to carry off surface water, they picked up vast quantities of excrement and dumped them right into the Thames–which was also the chief source for much of the newfangled piped water being delivered to many homes.
Johnson's book is a medical detective story (just tracking which homes were hooked up to which private water system was a nightmare). And like any medical detective, Snow was an astute observer of contradictory evidence. The brewers who worked in the local brewery didn't catch cholera. (They drank only their own product.) Cases occurred both among the poor renters upstairs in the tenements and the landlords living on the ground floors. If the sheer reek was infectious, why were the sewer-hunters so healthy?
Working in parallel with Snow was Rev. Henry Whitehead, a young curate in the parish, who attended many cases and burials. He knew his community very well, and at first he had no belief in Snow's theory of waterborne infection. But Snow patiently gathered his data, and it was Rev. Whitehead who found the index case: "Baby Lewis," whose mother had rinsed the dying child's diapers and thrown the water into the tenement cesspit–where it leaked into the famously clean and tasty water delivered by the Broad Street pump.
A local neighbourhood committee authorized the removal of the pump handle, but medical opinion was not changed overnight. It took decades for the miasmatics to be convinced (or simply to die off). My own medical hero, Rudolf Virchow, never believed in the germ theory.
Snow himself died of a stroke in 1858, aged 45, just as a June heat wave produced the "Great Stink," a pool of foul air that triggered the building of a proper water and sanitation system for London. Whitehead lived into the 1890s, and saw London fend off a cholera outbreak from Hamburg.
Steven Johnson argues that a disease like cholera relies on a sedentary human population crowded into a small place with no distinction between incoming water and outgoing excrement. London in 1854 had two million people jammed into a space of 30 miles. Now it has vastly more people, and no cholera at all. It took the concentration of people to create the outbreak, and to support a medical system with at least one careful thinker in its ranks.
Now, of course, we have a growing number of megacities, and this blog has chronicled their sorrows: the floods and H5N1 of Jakarta, Shanghai's floating pig carcasses and H7N9, H1N1 shutting down Mexico City, and cholera itself raging through Port-au-Prince. John Snow, Henry Whitehead, and Charles Dickens would have recognized something familiar about them all.
Like it or not, most of humanity will live in megacities for the foreseeable future, and will be the better for it. But they will need the kind of infrastructure that Queen Victoria's governments were willing to build (and which still keeps London healthy). Creating that infrastructure should be every government's first priority—not squabbling like toddlers over who gets to play with which offshore island, or who was rude to whom over some forgotten outrage.
Those who learned John Snow's lesson now have sewers and the prosperity that goes with them. But the ease of travel from countries still trapped in the 1850s means the "advanced" countries are vulnerable unless and until they take concrete steps to improve sanitation overseas.
A decent US-funded sewer and water system for Port-au-Prince would be a start. But only a start.