This book delves—in a pop-scientific way—into the 1850s cholera outbreak in London, England. This was at a time when cholera wasn't in the medical books and thoughts about miasma were flounced about by so-called medical professionals.

Johnson is very good at providing ample background information to whatever happens during this book, for example, the following two paragraphs:

Water closets were a tremendous breakthrough as far as quality of life was concerned, but they had a disastrous effect on the city’s sewage problem. Without a functioning sewer system to connect to, most WCs simply flushed their contents into existing cesspools, greatly increasing their tendency to overflow. According to one estimate, the average London household used 160 gallons of water a day in 1850. By 1856, thanks to the runaway success of the water closet, they were using 244 gallons.

But the single most important factor driving London’s waste-removal crisis was a matter of simple demography: the number of people generating waste had almost tripled in the space of fifty years. In the 1851 census, London had a population of 2.4 million people, making it the most populous city on the planet, up from around a million at the turn of the century. Even with a modern civic infrastructure, that kind of explosive growth is difficult to manage. But without infrastructure, two million people suddenly forced to share ninety square miles of space wasn’t just a disaster waiting to happen—it was a kind of permanent, rolling disaster, a vast organism destroying itself by laying waste to its habitat. Five hundred years after the fact, London was slowly re-creating the horrific demise of Richard the Raker: it was drowning in its own filth.

London's population exploded in size and nearly in crises; finding housing for everyone is one thing, but to try and keep sickness away proved impossible, especially when one considers that words from people who belonged to clerical professions carried the most heft where it came to matters medical (and scientific).

Descriptions of how cases of cholera broke out are detailed:

All that history would have weighed like a nightmare on Mr. G, as his condition worsened on Thursday. He may have begun vomiting during the night and most likely experienced muscle spasms and sharp abdominal pains. At a certain point, he would have been overtaken by a crushing thirst.

But the experience was largely dominated by one hideous process: vast quantities of water being evacuated from his bowels, strangely absent of smell and color, harboring only tiny white particles. Clinicians of the day dubbed this “rice-water stool.” Once you began emitting rice-water stools, odds were you’d be dead in a matter of hours. Mr. G would have been terribly aware of his fate, even as he battled the physical agony of the disease. One of cholera’s distinctive curses is that its sufferers remain mentally alert until the very last stages of the disease, fully conscious both of the pain that the disease has brought them and the sudden, shocking contraction of their life expectancy.

The Times had described this horrifying condition several years before in a long feature on the disease: “While the mechanism of life is suddenly arrested, the body emptied by a few rapid gushes of its serum, and reduced to a damp, dead…mass, the mind within remains untouched and clear,—shining strangely through the glazed eyes, with light unquenched and vivid,—a spirit, looking out in terror from a corpse.”

By Friday, Mr. G’s pulse would have been barely detectable, and a rough mask of blue, leathery skin would have covered his face. His condition would have matched this description of William Sproat from 1831: “countenance quite shrunk, eyes sunk, lips dark blue, as well as the skin of the lower extremities; the nails…livid.” Most of this is, to a certain extent, conjecture.

But one thing we know for certain: at one p.m. on Friday, as baby Lewis suffered quietly in the room next door, Mr. G’s heart stopped beating, barely twenty-four hours after showing the first symptoms of cholera. Within a few hours, another dozen Soho residents were dead.

This book almost turns into a complete hagiography where John Snow is concerned. He is the main character in this non-fiction book, which is nearly written in the way that a modern-day crime novel is: Snow's from a poor background, studied hard, worked his way up, and could have lived a relatively cozy existence as the man who started out modern-day anesthesiology. John Snow didn't do that.

Instead, he started looking into what was killing thousands of people and what the source of it could be, much like any modern-day forensic investigation could ramble along.

The idea of microscopic germs spreading disease would have been about as plausible as the existence of fairies to most practicing doctors of the day. And as Surgeon-in-Chief G. B. Childs’ letter-writing campaign to the Times suggested, laudanum was regularly prescribed for almost any ailment. The Victorian medical refrain was, essentially: Take a few hits of opium and call me in the morning.

This book is an easy read. I'm not one for pop-scientific books with oodles of fact, being nerdy in the extreme, but in spite of its monograph value, this book won me over, mainly through Johnson's style and well-written prose.

This is an analyst's book. It's divided into clear chapters and goes finely into details. There's not much flair over Johnson's writing, in a good way, which is apt, considering his near-dry British way of going over things; he walks the line between terse humour and in-depth medical detail in commendable ways.